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ba8251e8 GS |
1 | =head1 NAME |
2 | ||
063663a9 | 3 | perldelta - what's new for perl v5.6.0 |
ba8251e8 GS |
4 | |
5 | =head1 DESCRIPTION | |
6 | ||
7 | This document describes differences between the 5.005 release and this one. | |
8 | ||
7a95317d | 9 | =head1 Core Enhancements |
ba8251e8 | 10 | |
7a95317d | 11 | =head2 Interpreter cloning, threads, and concurrency |
e02fdbd2 | 12 | |
7a95317d GS |
13 | Perl 5.005_63 introduces the beginnings of support for running multiple |
14 | interpreters concurrently in different threads. In conjunction with | |
15 | the perl_clone() API call, which can be used to selectively duplicate | |
16 | the state of any given interpreter, it is possible to compile a | |
17 | piece of code once in an interpreter, clone that interpreter | |
18 | one or more times, and run all the resulting interpreters in distinct | |
19 | threads. | |
a5222a85 | 20 | |
7a95317d GS |
21 | On the Windows platform, this feature is used to emulate fork() at the |
22 | interpreter level. See L<perlfork> for details about that. | |
e02fdbd2 | 23 | |
7a95317d GS |
24 | This feature is still in evolution. It is eventually meant to be used |
25 | to selectively clone a subroutine and data reachable from that | |
26 | subroutine in a separate interpreter and run the cloned subroutine | |
27 | in a separate thread. Since there is no shared data between the | |
28 | interpreters, little or no locking will be needed (unless parts of | |
29 | the symbol table are explicitly shared). This is obviously intended | |
30 | to be an easy-to-use replacement for the existing threads support. | |
757edf6f | 31 | |
7a95317d GS |
32 | Support for cloning interpreters and interpreter concurrency can be |
33 | enabled using the -Dusethreads Configure option (see win32/Makefile for | |
34 | how to enable it on Windows.) The resulting perl executable will be | |
35 | functionally identical to one that was built with -Dmultiplicity, but | |
36 | the perl_clone() API call will only be available in the former. | |
4f25aa18 | 37 | |
7a95317d GS |
38 | -Dusethreads enables the cpp macro USE_ITHREADS by default, which in turn |
39 | enables Perl source code changes that provide a clear separation between | |
40 | the op tree and the data it operates with. The former is immutable, and | |
41 | can therefore be shared between an interpreter and all of its clones, | |
42 | while the latter is considered local to each interpreter, and is therefore | |
43 | copied for each clone. | |
4f25aa18 | 44 | |
7a95317d GS |
45 | Note that building Perl with the -Dusemultiplicity Configure option |
46 | is adequate if you wish to run multiple B<independent> interpreters | |
47 | concurrently in different threads. -Dusethreads only provides the | |
48 | additional functionality of the perl_clone() API call and other | |
49 | support for running B<cloned> interpreters concurrently. | |
08cd8952 | 50 | |
7a95317d GS |
51 | NOTE: This is an experimental feature. Implementation details are |
52 | subject to change. | |
08cd8952 | 53 | |
7a95317d | 54 | =head2 Lexically scoped warning categories |
08cd8952 | 55 | |
7a95317d GS |
56 | You can now control the granularity of warnings emitted by perl at a finer |
57 | level using the C<use warnings> pragma. L<warnings> and L<perllexwarn> | |
58 | have copious documentation on this feature. | |
08cd8952 | 59 | |
7a95317d | 60 | =head2 Unicode and UTF-8 support |
08cd8952 | 61 | |
7a95317d GS |
62 | Perl now uses UTF-8 as its internal representation for character |
63 | strings. The C<utf8> and C<bytes> pragmas are used to control this support | |
64 | in the current lexical scope. See L<perlunicode>, L<utf8> and L<bytes> for | |
65 | more information. | |
08cd8952 | 66 | |
7a95317d GS |
67 | This feature is expected to evolve quickly to support some form of I/O |
68 | disciplines that can be used to specify the kind of input and output data | |
69 | (bytes or characters). Until that happens, additional modules from CPAN | |
70 | will be needed to complete the toolkit for dealing with Unicode. | |
08cd8952 | 71 | |
7a95317d GS |
72 | NOTE: This should be considered an experimental feature. Implementation |
73 | details are subject to change. | |
74 | ||
75 | =head2 Support for interpolating named characters | |
76 | ||
77 | The new C<\N> escape interpolates named characters within strings. | |
78 | For example, C<"Hi! \N{WHITE SMILING FACE}"> evaluates to a string | |
79 | with a unicode smiley face at the end. | |
80 | ||
81 | =head2 "our" declarations | |
82 | ||
83 | An "our" declaration introduces a value that can be best understood | |
84 | as a lexically scoped symbolic alias to a global variable in the | |
85 | package that was current where the variable was declared. This is | |
86 | mostly useful as an alternative to the C<vars> pragma, but also provides | |
87 | the opportunity to introduce typing and other attributes for such | |
88 | variables. See L<perlfunc/our>. | |
89 | ||
90 | =head2 Support for strings represented as a vector of ordinals | |
91 | ||
92 | Literals of the form C<v1.2.3.4> are now parsed as a string composed | |
93 | of characters with the specified ordinals. This is an alternative, more | |
94 | readable way to construct (possibly unicode) strings instead of | |
95 | interpolating characters, as in C<"\x{1}\x{2}\x{3}\x{4}">. The leading | |
96 | C<v> may be omitted if there are more than two ordinals, so C<1.2.3> is | |
97 | parsed the same as C<v1.2.3>. | |
98 | ||
99 | Strings written in this form are also useful to represent version "numbers". | |
100 | It is easy to compare such version "numbers" (which are really just plain | |
101 | strings) using any of the usual string comparison operators C<eq>, C<ne>, | |
102 | C<lt>, C<gt>, etc., or perform bitwise string operations on them using C<|>, | |
103 | C<&>, etc. | |
104 | ||
105 | In conjunction with the new C<$^V> magic variable (which contains | |
106 | the perl version as a string), such literals can be used as a readable way | |
107 | to check if you're running a particular version of Perl: | |
108 | ||
109 | # this will parse in older versions of Perl also | |
110 | if ($^V and $^V gt v5.6.0) { | |
111 | # new features supported | |
112 | } | |
113 | ||
114 | C<require> and C<use> also have some special magic to support such literals. | |
115 | They will be interpreted as a version rather than as a module name: | |
116 | ||
117 | require v5.6.0; # croak if $^V lt v5.6.0 | |
118 | use v5.6.0; # same, but croaks at compile-time | |
119 | ||
120 | Alternatively, the C<v> may be omitted if there is more than one dot: | |
121 | ||
122 | require 5.6.0; | |
123 | use 5.6.0; | |
124 | ||
125 | Also, C<sprintf> and C<printf> support the Perl-specific format flag C<%v> | |
126 | to print ordinals of characters in arbitrary strings: | |
127 | ||
128 | printf "v%vd", $^V; # prints current version, such as "v5.5.650" | |
129 | printf "%*vX", ":", $addr; # formats IPv6 address | |
130 | printf "%*vb", " ", $bits; # displays bitstring | |
131 | ||
132 | See L<perldata/"Scalar value constructors"> for additional information. | |
08cd8952 | 133 | |
7a95317d | 134 | =head2 Improved Perl version numbering system |
44dcb63b | 135 | |
063663a9 | 136 | Beginning with Perl version 5.6.0, the version number convention has been |
44dcb63b GS |
137 | changed to a "dotted integer" scheme that is more commonly found in open |
138 | source projects. | |
139 | ||
140 | Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. | |
063663a9 | 141 | The next development series following v5.6.0 will be numbered v5.7.x, |
44dcb63b | 142 | beginning with v5.7.0, and the next major production release following |
063663a9 | 143 | v5.6.0 will be v5.8.0. |
44dcb63b GS |
144 | |
145 | The English module now sets $PERL_VERSION to $^V (a string value) rather | |
146 | than C<$]> (a numeric value). (This is a potential incompatibility. | |
147 | Send us a report via perlbug if you are affected by this.) | |
148 | ||
149 | The v1.2.3 syntax is also now legal in Perl. | |
150 | See L<Support for strings represented as a vector of ordinals> for more on that. | |
151 | ||
152 | To cope with the new versioning system's use of at least three significant | |
153 | digits for each version component, the method used for incrementing the | |
154 | subversion number has also changed slightly. We assume that versions older | |
063663a9 | 155 | than v5.6.0 have been incrementing the subversion component in multiples of |
44dcb63b | 156 | 10. Versions after v5.6.0 will increment them by 1. Thus, using the new |
063663a9 GS |
157 | notation, 5.005_03 is the "same" as v5.5.30, and the first maintenance |
158 | version following v5.6.0 will be v5.6.1 (which should be read as being | |
159 | equivalent to a floating point value of 5.006_001 in the older format, | |
160 | stored in C<$]>). | |
44dcb63b | 161 | |
7a95317d | 162 | =head2 New syntax for declaring subroutine attributes |
dd629d5b | 163 | |
7a95317d GS |
164 | Formerly, if you wanted to mark a subroutine as being a method call or |
165 | as requiring an automatic lock() when it is entered, you had to declare | |
166 | that with a C<use attrs> pragma in the body of the subroutine. | |
167 | That can now be accomplished with declaration syntax, like this: | |
dd629d5b | 168 | |
7a95317d GS |
169 | sub mymethod : locked method ; |
170 | ... | |
171 | sub mymethod : locked method { | |
172 | ... | |
173 | } | |
dd629d5b | 174 | |
7a95317d GS |
175 | sub othermethod :locked :method ; |
176 | ... | |
177 | sub othermethod :locked :method { | |
178 | ... | |
179 | } | |
dd629d5b | 180 | |
757edf6f | 181 | |
7a95317d GS |
182 | (Note how only the first C<:> is mandatory, and whitespace surrounding |
183 | the C<:> is optional.) | |
757edf6f | 184 | |
7a95317d GS |
185 | F<AutoSplit.pm> and F<SelfLoader.pm> have been updated to keep the attributes |
186 | with the stubs they provide. See L<attributes>. | |
a5222a85 | 187 | |
7a95317d | 188 | =head2 File and directory handles can be autovivified |
a5222a85 | 189 | |
7a95317d GS |
190 | Similar to how constructs such as C<< $x->[0] >> autovivify a reference, |
191 | handle constructors (open(), opendir(), pipe(), socketpair(), sysopen(), | |
192 | socket(), and accept()) now autovivify a file or directory handle | |
193 | if the handle passed to them is an uninitialized scalar variable. This | |
194 | allows the constructs such as C<open(my $fh, ...)> and C<open(local $fh,...)> | |
195 | to be used to create filehandles that will conveniently be closed | |
196 | automatically when the scope ends, provided there are no other references | |
197 | to them. This largely eliminates the need for typeglobs when opening | |
198 | filehandles that must be passed around, as in the following example: | |
a5222a85 | 199 | |
7a95317d GS |
200 | sub myopen { |
201 | open my $fh, "@_" | |
202 | or die "Can't open '@_': $!"; | |
203 | return $fh; | |
204 | } | |
a5222a85 | 205 | |
7a95317d GS |
206 | { |
207 | my $f = myopen("</etc/motd"); | |
208 | print <$f>; | |
209 | # $f implicitly closed here | |
210 | } | |
a5222a85 | 211 | |
7a95317d | 212 | =head2 open() with more than two arguments |
a5222a85 | 213 | |
7a95317d GS |
214 | If open() is passed three arguments instead of two, the second argument |
215 | is used as the mode and the third argument is taken to be the file name. | |
216 | This is primarily useful for protecting against unintended magic behavior | |
217 | of the traditional two-argument form. See L<perlfunc/open>. | |
a5222a85 | 218 | |
7a95317d | 219 | =head2 64-bit support |
a5222a85 | 220 | |
7a95317d | 221 | Any platform that has 64-bit integers either |
a5222a85 | 222 | |
7a95317d GS |
223 | (1) natively as longs or ints |
224 | (2) via special compiler flags | |
225 | (3) using long long or int64_t | |
a5222a85 | 226 | |
7a95317d | 227 | is able to use "quads" (64-bit integers) as follows: |
a5222a85 | 228 | |
7a95317d | 229 | =over 4 |
a5222a85 | 230 | |
7a95317d | 231 | =item * |
a5222a85 | 232 | |
7a95317d | 233 | constants (decimal, hexadecimal, octal, binary) in the code |
a5222a85 | 234 | |
7a95317d | 235 | =item * |
a5222a85 | 236 | |
7a95317d | 237 | arguments to oct() and hex() |
a5222a85 | 238 | |
7a95317d | 239 | =item * |
a5222a85 | 240 | |
7a95317d | 241 | arguments to print(), printf() and sprintf() (flag prefixes ll, L, q) |
a5222a85 | 242 | |
7a95317d | 243 | =item * |
39429b3b | 244 | |
7a95317d | 245 | printed as such |
39429b3b | 246 | |
7a95317d | 247 | =item * |
39429b3b | 248 | |
7a95317d | 249 | pack() and unpack() "q" and "Q" formats |
39429b3b | 250 | |
7a95317d | 251 | =item * |
39429b3b | 252 | |
7a95317d GS |
253 | in basic arithmetics: + - * / % (NOTE: operating close to the limits |
254 | of the integer values may produce surprising results) | |
39429b3b | 255 | |
7a95317d | 256 | =item * |
39429b3b | 257 | |
7a95317d GS |
258 | in bit arithmetics: & | ^ ~ << >> (NOTE: these used to be forced |
259 | to be 32 bits wide but now operate on the full native width.) | |
39429b3b | 260 | |
7a95317d | 261 | =item * |
39429b3b | 262 | |
7a95317d | 263 | vec() |
cceca5ed GS |
264 | |
265 | =back | |
266 | ||
7a95317d GS |
267 | Note that unless you have the case (a) you will have to configure |
268 | and compile Perl using the -Duse64bitint Configure flag. | |
67d3893f | 269 | |
7a95317d GS |
270 | NOTE: The Configure flags -Duselonglong and -Duse64bits have been |
271 | deprecated. Use -Duse64bitint instead. | |
67d3893f | 272 | |
7a95317d GS |
273 | There are actually two modes of 64-bitness: the first one is achieved |
274 | using Configure -Duse64bitint and the second one using Configure | |
275 | -Duse64bitall. The difference is that the first one is minimal and | |
276 | the second one maximal. The first works in more places than the second. | |
67d3893f | 277 | |
7a95317d GS |
278 | The C<use64bitint> does only as much as is required to get 64-bit |
279 | integers into Perl (this may mean, for example, using "long longs") | |
280 | while your memory may still be limited to 2 gigabytes (because your | |
281 | pointers could still be 32-bit). Note that the name C<64bitint> does | |
282 | not imply that your C compiler will be using 64-bit C<int>s (it might, | |
283 | but it doesn't have to): the C<use64bitint> means that you will be | |
284 | able to have 64 bits wide scalar values. | |
67d3893f | 285 | |
7a95317d GS |
286 | The C<use64bitall> goes all the way by attempting to switch also |
287 | integers (if it can), longs (and pointers) to being 64-bit. This may | |
288 | create an even more binary incompatible Perl than -Duse64bitint: the | |
289 | resulting executable may not run at all in a 32-bit box, or you may | |
290 | have to reboot/reconfigure/rebuild your operating system to be 64-bit | |
291 | aware. | |
67d3893f | 292 | |
7a95317d GS |
293 | Natively 64-bit systems like Alpha and Cray need neither -Duse64bitint |
294 | nor -Duse64bitall. | |
67d3893f | 295 | |
7a95317d GS |
296 | Last but not least: note that due to Perl's habit of always using |
297 | floating point numbers, the quads are still not true integers. | |
298 | When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned, | |
299 | -9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they | |
300 | are silently promoted to floating point numbers, after which they will | |
301 | start losing precision (in their lower digits). | |
67d3893f | 302 | |
7a95317d GS |
303 | NOTE: 64-bit support is still experimental on most platforms. |
304 | Existing support only covers the LP64 data model. In particular, the | |
305 | LLP64 data model is not yet supported. 64-bit libraries and system | |
306 | APIs on many platforms have not stabilized--your mileage may vary. | |
642f9deb | 307 | |
7a95317d | 308 | =head2 Large file support |
a5222a85 | 309 | |
7a95317d GS |
310 | If you have filesystems that support "large files" (files larger than |
311 | 2 gigabytes), you may now also be able to create and access them from | |
312 | Perl. | |
a5222a85 | 313 | |
7a95317d GS |
314 | NOTE: The default action is to enable large file support, if |
315 | available on the platform. | |
a5222a85 | 316 | |
7a95317d GS |
317 | If the large file support is on, and you have a Fcntl constant |
318 | O_LARGEFILE, the O_LARGEFILE is automatically added to the flags | |
319 | of sysopen(). | |
a5222a85 | 320 | |
7a95317d GS |
321 | Beware that unless your filesystem also supports "sparse files" seeking |
322 | to umpteen petabytes may be inadvisable. | |
642f9deb | 323 | |
7a95317d GS |
324 | Note that in addition to requiring a proper file system to do large |
325 | files you may also need to adjust your per-process (or your | |
326 | per-system, or per-process-group, or per-user-group) maximum filesize | |
327 | limits before running Perl scripts that try to handle large files, | |
328 | especially if you intend to write such files. | |
a5222a85 | 329 | |
7a95317d GS |
330 | Finally, in addition to your process/process group maximum filesize |
331 | limits, you may have quota limits on your filesystems that stop you | |
332 | (your user id or your user group id) from using large files. | |
a5222a85 | 333 | |
7a95317d GS |
334 | Adjusting your process/user/group/file system/operating system limits |
335 | is outside the scope of Perl core language. For process limits, you | |
336 | may try increasing the limits using your shell's limits/limit/ulimit | |
337 | command before running Perl. The BSD::Resource extension (not | |
338 | included with the standard Perl distribution) may also be of use, it | |
339 | offers the getrlimit/setrlimit interface that can be used to adjust | |
340 | process resource usage limits, including the maximum filesize limit. | |
a5222a85 | 341 | |
7a95317d | 342 | =head2 Long doubles |
67d3893f | 343 | |
7a95317d GS |
344 | In some systems you may be able to use long doubles to enhance the |
345 | range and precision of your double precision floating point numbers | |
346 | (that is, Perl's numbers). Use Configure -Duselongdouble to enable | |
347 | this support (if it is available). | |
49c10eea | 348 | |
7a95317d | 349 | =head2 "more bits" |
67d3893f | 350 | |
7a95317d GS |
351 | You can "Configure -Dusemorebits" to turn on both the 64-bit support |
352 | and the long double support. | |
ba8251e8 | 353 | |
7a95317d | 354 | =head2 Enhanced support for sort() subroutines |
9d73390d | 355 | |
7a95317d GS |
356 | Perl subroutines with a prototype of C<($$)>, and XSUBs in general, can |
357 | now be used as sort subroutines. In either case, the two elements to | |
358 | be compared are passed as normal parameters in @_. See L<perlfunc/sort>. | |
21bad921 | 359 | |
7a95317d GS |
360 | For unprototyped sort subroutines, the historical behavior of passing |
361 | the elements to be compared as the global variables $a and $b remains | |
362 | unchanged. | |
9d73390d | 363 | |
7a95317d | 364 | =head2 C<sort $coderef @foo> allowed |
af365420 | 365 | |
7a95317d GS |
366 | sort() did not accept a subroutine reference as the comparison |
367 | function in earlier versions. This is now permitted. | |
af365420 | 368 | |
7a95317d | 369 | =head2 File globbing implemented internally |
af365420 | 370 | |
7a95317d GS |
371 | Perl now uses the File::Glob implementation of the glob() operator |
372 | automatically. This avoids using an external csh process and the | |
373 | problems associated with it. | |
af365420 | 374 | |
7a95317d GS |
375 | NOTE: This is currently an experimental feature. Interfaces and |
376 | implementation are subject to change. | |
af365420 | 377 | |
7a95317d | 378 | =item Support for CHECK blocks |
af365420 | 379 | |
7a95317d GS |
380 | In addition to C<BEGIN>, C<INIT>, C<END>, C<DESTROY> and C<AUTOLOAD>, |
381 | subroutines named C<CHECK> are now special. These are queued up during | |
382 | compilation and behave similar to END blocks, except they are called at | |
383 | the end of compilation rather than at the end of execution. They cannot | |
384 | be called directly. | |
af365420 | 385 | |
7a95317d | 386 | =head2 POSIX character class syntax [: :] supported |
af365420 | 387 | |
7a95317d GS |
388 | For example to match alphabetic characters use /[[:alpha:]]/. |
389 | See L<perlre> for details. | |
9d73390d | 390 | |
7a95317d | 391 | =item Better pseudo-random number generator |
9d73390d | 392 | |
7a95317d GS |
393 | In 5.005_0x and earlier, perl's rand() function used the C library |
394 | rand(3) function. As of 5.005_52, Configure tests for drand48(), | |
395 | random(), and rand() (in that order) and picks the first one it finds. | |
a5222a85 | 396 | |
7a95317d | 397 | These changes should result in better random numbers from rand(). |
a5222a85 | 398 | |
7a95317d | 399 | =head2 Improved C<qw//> operator |
a5222a85 | 400 | |
7a95317d GS |
401 | The C<qw//> operator is now evaluated at compile time into a true list |
402 | instead of being replaced with a run time call to C<split()>. This | |
403 | removes the confusing misbehaviour of C<qw//> in scalar context, which | |
404 | had inherited that behaviour from split(). | |
a5222a85 | 405 | |
7a95317d | 406 | Thus: |
16070b82 | 407 | |
7a95317d | 408 | $foo = ($bar) = qw(a b c); print "$foo|$bar\n"; |
16070b82 | 409 | |
7a95317d | 410 | now correctly prints "3|a", instead of "2|a". |
16070b82 | 411 | |
7a95317d | 412 | =item Better worst-case behavior of hashes |
16070b82 | 413 | |
7a95317d GS |
414 | Small changes in the hashing algorithm have been implemented in |
415 | order to improve the distribution of lower order bits in the | |
416 | hashed value. This is expected to yield better performance on | |
417 | keys that are repeated sequences. | |
16070b82 | 418 | |
7a95317d | 419 | =head2 pack() format 'Z' supported |
16070b82 | 420 | |
7a95317d GS |
421 | The new format type 'Z' is useful for packing and unpacking null-terminated |
422 | strings. See L<perlfunc/"pack">. | |
16070b82 | 423 | |
7a95317d | 424 | =head2 pack() format modifier '!' supported |
a5222a85 | 425 | |
7a95317d GS |
426 | The new format type modifier '!' is useful for packing and unpacking |
427 | native shorts, ints, and longs. See L<perlfunc/"pack">. | |
dd629d5b | 428 | |
7a95317d | 429 | =head2 pack() and unpack() support counted strings |
dd629d5b | 430 | |
7a95317d GS |
431 | The template character '/' can be used to specify a counted string |
432 | type to be packed or unpacked. See L<perlfunc/"pack">. | |
1761cee5 | 433 | |
7a95317d | 434 | =head2 Comments in pack() templates |
1761cee5 | 435 | |
7a95317d GS |
436 | The '#' character in a template introduces a comment up to |
437 | end of the line. This facilitates documentation of pack() | |
438 | templates. | |
44dcb63b | 439 | |
a5222a85 GS |
440 | =head2 Weak references |
441 | ||
d4629d6a GS |
442 | In previous versions of Perl, you couldn't cache objects so as |
443 | to allow them to be deleted if the last reference from outside | |
444 | the cache is deleted. The reference in the cache would hold a | |
445 | reference count on the object and the objects would never be | |
446 | destroyed. | |
447 | ||
448 | Another familiar problem is with circular references. When an | |
449 | object references itself, its reference count would never go | |
450 | down to zero, and it would not get destroyed until the program | |
451 | is about to exit. | |
452 | ||
453 | Weak references solve this by allowing you to "weaken" any | |
454 | reference, that is, make it not count towards the reference count. | |
455 | When the last non-weak reference to an object is deleted, the object | |
456 | is destroyed and all the weak references to the object are | |
457 | automatically undef-ed. | |
a5222a85 | 458 | |
d4629d6a GS |
459 | To use this feature, you need the WeakRef package from CPAN, which |
460 | contains additional documentation. | |
461 | ||
7a95317d | 462 | NOTE: This is an experimental feature. Details are subject to change. |
becf2bd3 | 463 | |
5fdc711f GS |
464 | =head2 Binary numbers supported |
465 | ||
4f19785b WSI |
466 | Binary numbers are now supported as literals, in s?printf formats, and |
467 | C<oct()>: | |
468 | ||
14218588 GS |
469 | $answer = 0b101010; |
470 | printf "The answer is: %b\n", oct("0b101010"); | |
4f19785b | 471 | |
7a95317d GS |
472 | =head2 Lvalue subroutines |
473 | ||
474 | Subroutines can now return modifiable lvalues. | |
475 | See L<perlsub/"Lvalue subroutines">. | |
476 | ||
477 | NOTE: This is an experimental feature. Details are subject to change. | |
478 | ||
a5222a85 GS |
479 | =head2 Some arrows may be omitted in calls through references |
480 | ||
481 | Perl now allows the arrow to be omitted in many constructs | |
482 | involving subroutine calls through references. For example, | |
c47ff5f1 | 483 | C<< $foo[10]->('foo') >> may now be written C<$foo[10]('foo')>. |
a5222a85 | 484 | This is rather similar to how the arrow may be omitted from |
c47ff5f1 GS |
485 | C<< $foo[10]->{'foo'} >>. Note however, that the arrow is still |
486 | required for C<< foo(10)->('bar') >>. | |
a5222a85 | 487 | |
7a95317d GS |
488 | =head2 Boolean assignment operators are legal lvalues |
489 | ||
490 | Constructs such as C<($a ||= 2) += 1> are now allowed. | |
491 | ||
afebc493 GS |
492 | =head2 exists() is supported on subroutine names |
493 | ||
494 | The exists() builtin now works on subroutine names. A subroutine | |
495 | is considered to exist if it has been declared (even if implicitly). | |
496 | See L<perlfunc/exists> for examples. | |
497 | ||
01020589 GS |
498 | =head2 exists() and delete() are supported on array elements |
499 | ||
500 | The exists() and delete() builtins now work on simple arrays as well. | |
501 | The behavior is similar to that on hash elements. | |
502 | ||
8ea97a1e | 503 | exists() can be used to check whether an array element has been |
8216c1fd GS |
504 | initialized. This avoids autovivifying array elements that don't exist. |
505 | If the array is tied, the EXISTS() method in the corresponding tied | |
506 | package will be invoked. | |
8ea97a1e GS |
507 | |
508 | delete() may be used to remove an element from the array and return | |
4375e838 | 509 | it. The array element at that position returns to its uninitialized |
8ea97a1e GS |
510 | state, so that testing for the same element with exists() will return |
511 | false. If the element happens to be the one at the end, the size of | |
8216c1fd GS |
512 | the array also shrinks up to the highest element that tests true for |
513 | exists(), or 0 if none such is found. If the array is tied, the DELETE() | |
514 | method in the corresponding tied package will be invoked. | |
01020589 GS |
515 | |
516 | See L<perlfunc/exists> and L<perlfunc/delete> for examples. | |
517 | ||
7a95317d | 518 | =head2 Pseudo-hashes work better |
9c107f78 | 519 | |
7a95317d GS |
520 | Dereferencing some types of reference values in a pseudo-hash, |
521 | such as C<< $ph->{foo}[1] >>, was accidentally disallowed. This has | |
522 | been corrected. | |
4bca7e4f | 523 | |
7a95317d GS |
524 | When applied to a pseudo-hash element, exists() now reports whether |
525 | the specified value exists, not merely if the key is valid. | |
9c107f78 | 526 | |
7a95317d GS |
527 | delete() now works on pseudo-hashes. When given a pseudo-hash element |
528 | or slice it deletes the values corresponding to the keys (but not the keys | |
529 | themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">. | |
a5222a85 | 530 | |
7a95317d GS |
531 | Pseudo-hash slices with constant keys are now optimized to array lookups |
532 | at compile-time. | |
a5222a85 | 533 | |
7a95317d | 534 | List assignments to pseudo-hash slices are now supported. |
9c107f78 | 535 | |
7a95317d GS |
536 | The C<fields> pragma now provides ways to create pseudo-hashes, via |
537 | fields::new() and fields::phash(). See L<fields>. | |
9c107f78 | 538 | |
7a95317d GS |
539 | NOTE: The pseudo-hash data type continues to be experimental. |
540 | Limiting oneself to the interface elements provided by the | |
541 | fields pragma will provide protection from any future changes. | |
a5222a85 | 542 | |
7a95317d | 543 | =head2 Automatic flushing of output buffers |
a5222a85 | 544 | |
7a95317d GS |
545 | fork(), exec(), system(), qx//, and pipe open()s now flush buffers |
546 | of all files opened for output when the operation was attempted. This | |
547 | mostly eliminates confusing buffering mishaps suffered by users unaware | |
548 | of how Perl internally handles I/O. | |
9c107f78 | 549 | |
7a95317d GS |
550 | This is not supported on some platforms like Solaris where a suitably |
551 | correct implementation of fflush(NULL) isn't available. | |
9c107f78 | 552 | |
7a95317d | 553 | =head2 Better diagnostics on meaningless filehandle operations |
a5222a85 | 554 | |
7a95317d GS |
555 | Constructs such as C<< open(<FH>) >> and C<< close(<FH>) >> |
556 | are compile time errors. Attempting to read from filehandles that | |
557 | were opened only for writing will now produce warnings (just as | |
558 | writing to read-only filehandles does). | |
a5222a85 | 559 | |
7a95317d | 560 | =head2 Where possible, buffered data discarded from duped input filehandle |
a5222a85 | 561 | |
7a95317d GS |
562 | C<< open(NEW, "<&OLD") >> now attempts to discard any data that |
563 | was previously read and buffered in C<OLD> before duping the handle. | |
564 | On platforms where doing this is allowed, the next read operation | |
565 | on C<NEW> will return the same data as the corresponding operation | |
566 | on C<OLD>. Formerly, it would have returned the data from the start | |
567 | of the following disk block instead. | |
a5222a85 | 568 | |
7a95317d | 569 | =head2 eof() has the same old magic as <> |
1fad5d67 | 570 | |
7a95317d GS |
571 | C<eof()> would return true if no attempt to read from C<< <> >> had |
572 | yet been made. C<eof()> has been changed to have a little magic of its | |
573 | own, it now opens the C<< <> >> files. | |
972b05a9 | 574 | |
7a95317d | 575 | =head2 binmode() can be used to set :crlf and :raw modes |
972b05a9 | 576 | |
7a95317d GS |
577 | binmode() now accepts a second argument that specifies a discipline |
578 | for the handle in question. The two pseudo-disciplines ":raw" and | |
579 | ":crlf" are currently supported on DOS-derivative platforms. | |
580 | See L<perlfunc/"binmode"> and L<open>. | |
9c107f78 | 581 | |
7a95317d | 582 | =head2 C<-T> filetest recognizes UTF-8 encoded files as "text" |
9c107f78 | 583 | |
7a95317d GS |
584 | The algorithm used for the C<-T> filetest has been enhanced to |
585 | correctly identify UTF-8 content as "text". | |
9c107f78 | 586 | |
7a95317d | 587 | =head2 system(), backticks and pipe open now reflect exec() failure |
55f6b6ec | 588 | |
7a95317d GS |
589 | On Unix and similar platforms, system(), qx() and open(FOO, "cmd |") |
590 | etc., are implemented via fork() and exec(). When the underlying | |
591 | exec() fails, earlier versions did not report the error properly, | |
592 | since the exec() happened to be in a different process. | |
55f6b6ec | 593 | |
7a95317d GS |
594 | The child process now communicates with the parent about the |
595 | error in launching the external command, which allows these | |
596 | constructs to return with their usual error value and set $!. | |
49c10eea | 597 | |
7a95317d | 598 | =head2 Improved diagnostics |
49c10eea | 599 | |
7a95317d GS |
600 | Line numbers are no longer suppressed (under most likely circumstances) |
601 | during the global destruction phase. | |
2d4389e4 | 602 | |
7a95317d GS |
603 | Diagnostics emitted from code running in threads other than the main |
604 | thread are now accompanied by the thread ID. | |
2d4389e4 | 605 | |
7a95317d GS |
606 | Embedded null characters in diagnostics now actually show up. They |
607 | used to truncate the message in prior versions. | |
55f6b6ec | 608 | |
7a95317d GS |
609 | $foo::a and $foo::b are now exempt from "possible typo" warnings only |
610 | if sort() is encountered in package C<foo>. | |
55f6b6ec | 611 | |
7a95317d GS |
612 | Unrecognized alphabetic escapes encountered when parsing quote |
613 | constructs now generate a warning, since they may take on new | |
614 | semantics in later versions of Perl. | |
2d4389e4 | 615 | |
7a95317d GS |
616 | Many diagnostics now report the internal operation in which the warning |
617 | was provoked, like so: | |
eed7fde4 | 618 | |
7a95317d GS |
619 | Use of uninitialized value in concatenation (.) at (eval 1) line 1. |
620 | Use of uninitialized value in print at (eval 1) line 1. | |
eed7fde4 | 621 | |
7a95317d GS |
622 | Diagnostics that occur within eval may also report the file and line |
623 | number where the eval is located, in addition to the eval sequence | |
624 | number and the line number within the evaluated text itself. For | |
625 | example: | |
475d79b5 | 626 | |
7a95317d | 627 | Not enough arguments for scalar at (eval 4)[newlib/perl5db.pl:1411] line 2, at EOF |
aa855319 | 628 | |
7a95317d | 629 | =head2 Diagnostics follow STDERR |
aa855319 | 630 | |
7a95317d GS |
631 | Diagnostic output now goes to whichever file the C<STDERR> handle |
632 | is pointing at, instead of always going to the underlying C runtime | |
633 | library's C<stderr>. | |
aa855319 | 634 | |
7a95317d | 635 | =item More consistent close-on-exec behavior |
09bef843 | 636 | |
7a95317d GS |
637 | On systems that support a close-on-exec flag on filehandles, the |
638 | flag is now set for any handles created by pipe(), socketpair(), | |
639 | socket(), and accept(), if that is warranted by the value of $^F | |
640 | that may be in effect. Earlier versions neglected to set the flag | |
641 | for handles created with these operators. See L<perlfunc/pipe>, | |
642 | L<perlfunc/socketpair>, L<perlfunc/socket>, L<perlfunc/accept>, | |
643 | and L<perlvar/$^F>. | |
43481408 | 644 | |
7a95317d | 645 | =head2 syswrite() ease-of-use |
43481408 | 646 | |
7a95317d | 647 | The length argument of C<syswrite()> has become optional. |
43481408 | 648 | |
62c18ce2 GS |
649 | =head2 Better syntax checks on parenthesized unary operators |
650 | ||
651 | Expressions such as: | |
652 | ||
14218588 GS |
653 | print defined(&foo,&bar,&baz); |
654 | print uc("foo","bar","baz"); | |
655 | undef($foo,&bar); | |
62c18ce2 | 656 | |
7711098a | 657 | used to be accidentally allowed in earlier versions, and produced |
14218588 GS |
658 | unpredictable behaviour. Some produced ancillary warnings |
659 | when used in this way; others silently did the wrong thing. | |
62c18ce2 GS |
660 | |
661 | The parenthesized forms of most unary operators that expect a single | |
14218588 GS |
662 | argument now ensure that they are not called with more than one |
663 | argument, making the cases shown above syntax errors. The usual | |
664 | behaviour of: | |
62c18ce2 | 665 | |
14218588 GS |
666 | print defined &foo, &bar, &baz; |
667 | print uc "foo", "bar", "baz"; | |
668 | undef $foo, &bar; | |
62c18ce2 GS |
669 | |
670 | remains unchanged. See L<perlop>. | |
671 | ||
7a95317d | 672 | =head2 Bit operators support full native integer width |
26ef7447 | 673 | |
7a95317d GS |
674 | The bit operators (& | ^ ~ << >>) now operate on the full native |
675 | integral width (the exact size of which is available in $Config{ivsize}). | |
676 | For example, if your platform is either natively 64-bit or if Perl | |
677 | has been configured to use 64-bit integers, these operations apply | |
678 | to 8 bytes (as opposed to 4 bytes on 32-bit platforms). | |
679 | For portability, be sure to mask off the excess bits in the result of | |
680 | unary C<~>, e.g., C<~$x & 0xffffffff>. | |
26ef7447 | 681 | |
7a95317d | 682 | =head2 Improved security features |
8127e0e3 | 683 | |
7a95317d GS |
684 | More potentially unsafe operations taint their results for improved |
685 | security. | |
5a929a98 | 686 | |
7a95317d GS |
687 | The C<passwd> and C<shell> fields returned by the getpwent(), getpwnam(), |
688 | and getpwuid() are now tainted, because the user can affect their own | |
689 | encrypted password and login shell. | |
5a929a98 | 690 | |
7a95317d GS |
691 | The variable modified by shmread(), and messages returned by msgrcv() |
692 | (and its object-oriented interface IPC::SysV::Msg::rcv) are also tainted, | |
693 | because other untrusted processes can modify messages and shared memory | |
694 | segments for their own nefarious purposes. | |
ee3907e2 | 695 | |
7a95317d | 696 | =item More functional bareword prototype (*) |
ee3907e2 | 697 | |
7a95317d GS |
698 | Bareword prototypes have been rationalized to enable them to be used |
699 | to override builtins that accept barewords and interpret them in | |
700 | a special way, such as C<require> or C<do>. | |
f29c64d6 | 701 | |
7a95317d GS |
702 | Arguments prototyped as C<*> will now be visible within the subroutine |
703 | as either a simple scalar or as a reference to a typeglob. | |
704 | See L<perlsub/Prototypes>. | |
f29c64d6 | 705 | |
7a95317d | 706 | =head2 C<require> and C<do> may be overridden |
a5222a85 | 707 | |
7a95317d GS |
708 | C<require> and C<do 'file'> operations may be overridden locally |
709 | by importing subroutines of the same name into the current package | |
710 | (or globally by importing them into the CORE::GLOBAL:: namespace). | |
711 | Overriding C<require> will also affect C<use>, provided the override | |
712 | is visible at compile-time. | |
713 | See L<perlsub/"Overriding Built-in Functions">. | |
a5222a85 | 714 | |
2b92dfce GS |
715 | =head2 $^X variables may now have names longer than one character |
716 | ||
717 | Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax | |
718 | error. Now variable names that begin with a control character may be | |
719 | arbitrarily long. However, for compatibility reasons, these variables | |
720 | I<must> be written with explicit braces, as C<${^XY}> for example. | |
14218588 | 721 | C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more |
2b92dfce GS |
722 | than one control character, such as C<${^XY^Z}>, are illegal. |
723 | ||
14218588 GS |
724 | The old syntax has not changed. As before, `^X' may be either a |
725 | literal control-X character or the two-character sequence `caret' plus | |
726 | `X'. When braces are omitted, the variable name stops after the | |
2b92dfce | 727 | control character. Thus C<"$^XYZ"> continues to be synonymous with |
7711098a | 728 | C<$^X . "YZ"> as before. |
2b92dfce GS |
729 | |
730 | As before, lexical variables may not have names beginning with control | |
731 | characters. As before, variables whose names begin with a control | |
14218588 GS |
732 | character are always forced to be in package `main'. All such variables |
733 | are reserved for future extensions, except those that begin with | |
09bef843 | 734 | C<^_>, which may be used by user programs and are guaranteed not to |
14218588 | 735 | acquire special meaning in any future version of Perl. |
2b92dfce | 736 | |
a5222a85 GS |
737 | =head2 New variable $^C reflects C<-c> switch |
738 | ||
08cd8952 | 739 | C<$^C> has a boolean value that reflects whether perl is being run |
a5222a85 GS |
740 | in compile-only mode (i.e. via the C<-c> switch). Since |
741 | BEGIN blocks are executed under such conditions, this variable | |
742 | enables perl code to determine whether actions that make sense | |
743 | only during normal running are warranted. See L<perlvar>. | |
744 | ||
063663a9 | 745 | =head2 New variable $^V contains Perl version as a string |
16070b82 | 746 | |
da2094fd | 747 | C<$^V> contains the Perl version number as a string composed of |
642f9deb | 748 | characters whose ordinals match the version numbers, i.e. v5.6.0. |
063663a9 | 749 | This may be used in string comparisons. |
44dcb63b GS |
750 | |
751 | See C<Support for strings represented as a vector of ordinals> for an | |
752 | example. | |
16070b82 | 753 | |
a5222a85 GS |
754 | =head2 Optional Y2K warnings |
755 | ||
756 | If Perl is built with the cpp macro C<PERL_Y2KWARN> defined, | |
757 | it emits optional warnings when concatenating the number 19 | |
758 | with another number. | |
759 | ||
760 | This behavior must be specifically enabled when running Configure. | |
b4bc034f | 761 | See F<INSTALL> and F<README.Y2K>. |
a5222a85 | 762 | |
7a95317d | 763 | =head1 Modules and Pragmata |
fbad3eb5 | 764 | |
7a95317d | 765 | =head2 Modules |
0244c3a4 | 766 | |
7a95317d | 767 | =over 4 |
0244c3a4 | 768 | |
7a95317d | 769 | =item attributes |
0244c3a4 | 770 | |
7a95317d GS |
771 | While used internally by Perl as a pragma, this module also |
772 | provides a way to fetch subroutine and variable attributes. | |
773 | See L<attributes>. | |
0244c3a4 | 774 | |
7a95317d | 775 | =item B |
a5222a85 | 776 | |
7a95317d GS |
777 | The Perl Compiler suite has been extensively reworked for this |
778 | release. More of the standard Perl testsuite passes when run | |
779 | under the Compiler, but there is still a significant way to | |
780 | go to achieve production quality compiled executables. | |
a5222a85 | 781 | |
7a95317d | 782 | NOTE: The Compiler suite remains highly experimental. The |
4375e838 | 783 | generated code may not be correct, even when it manages to execute |
7a95317d | 784 | without errors. |
a5222a85 | 785 | |
7a95317d | 786 | =item Benchmark |
45bc9206 | 787 | |
7a95317d GS |
788 | Overall, Benchmark results exhibit lower average error and better timing |
789 | accuracy. | |
45bc9206 | 790 | |
7a95317d GS |
791 | You can now run tests for I<n> seconds instead of guessing the right |
792 | number of tests to run: e.g., timethese(-5, ...) will run each | |
793 | code for at least 5 CPU seconds. Zero as the "number of repetitions" | |
794 | means "for at least 3 CPU seconds". The output format has also | |
795 | changed. For example: | |
023ceb80 | 796 | |
7a95317d | 797 | use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}}) |
af8c498a | 798 | |
7a95317d | 799 | will now output something like this: |
af8c498a | 800 | |
7a95317d GS |
801 | Benchmark: running a, b, each for at least 5 CPU seconds... |
802 | a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516) | |
803 | b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686) | |
a5222a85 | 804 | |
7a95317d GS |
805 | New features: "each for at least N CPU seconds...", "wallclock secs", |
806 | and the "@ operations/CPU second (n=operations)". | |
a5222a85 | 807 | |
7a95317d GS |
808 | timethese() now returns a reference to a hash of Benchmark objects containing |
809 | the test results, keyed on the names of the tests. | |
820475bd | 810 | |
7a95317d GS |
811 | timethis() now returns the iterations field in the Benchmark result object |
812 | instead of 0. | |
820475bd | 813 | |
7a95317d GS |
814 | timethese(), timethis(), and the new cmpthese() (see below) can also take |
815 | a format specifier of 'none' to suppress output. | |
a5222a85 | 816 | |
7a95317d GS |
817 | A new function countit() is just like timeit() except that it takes a |
818 | TIME instead of a COUNT. | |
a5222a85 | 819 | |
7a95317d GS |
820 | A new function cmpthese() prints a chart comparing the results of each test |
821 | returned from a timethese() call. For each possible pair of tests, the | |
822 | percentage speed difference (iters/sec or seconds/iter) is shown. | |
a5222a85 | 823 | |
7a95317d | 824 | For other details, see L<Benchmark>. |
a5222a85 | 825 | |
7a95317d | 826 | =item ByteLoader |
a5222a85 | 827 | |
7a95317d GS |
828 | The ByteLoader is a dedicated extension to generate and run |
829 | Perl bytecode. See L<ByteLoader>. | |
a5222a85 | 830 | |
7a95317d | 831 | =item constant |
a5222a85 | 832 | |
7a95317d | 833 | References can now be used. |
a5222a85 | 834 | |
7a95317d GS |
835 | The new version also allows a leading underscore in constant names, but |
836 | disallows a double leading underscore (as in "__LINE__"). Some other names | |
837 | are disallowed or warned against, including BEGIN, END, etc. Some names | |
838 | which were forced into main:: used to fail silently in some cases; now they're | |
839 | fatal (outside of main::) and an optional warning (inside of main::). | |
840 | The ability to detect whether a constant had been set with a given name has | |
841 | been added. | |
4bca7e4f | 842 | |
7a95317d | 843 | See L<constant>. |
a5222a85 | 844 | |
7a95317d | 845 | =item charnames |
a5222a85 | 846 | |
7a95317d | 847 | This pragma implements the C<\N> string escape. See L<charnames>. |
01020589 | 848 | |
7a95317d | 849 | =item Data::Dumper |
479ba383 | 850 | |
7a95317d GS |
851 | A C<Maxdepth> setting can be specified to avoid venturing |
852 | too deeply into deep data structures. See L<Data::Dumper>. | |
479ba383 | 853 | |
7a95317d GS |
854 | The XSUB implementation of Dump() is now automatically called if the |
855 | C<Useqq> setting is not in use. | |
a5222a85 | 856 | |
7a95317d | 857 | Dumping C<qr//> objects works correctly. |
a5222a85 | 858 | |
7a95317d | 859 | =item DB |
a5222a85 | 860 | |
7a95317d GS |
861 | C<DB> is an experimental module that exposes a clean abstraction |
862 | to Perl's debugging API. | |
a5222a85 | 863 | |
7a95317d | 864 | =item DB_File |
a5222a85 | 865 | |
7a95317d GS |
866 | DB_File can now be built with Berkeley DB versions 1, 2 or 3. |
867 | See C<ext/DB_File/Changes>. | |
a5222a85 | 868 | |
7a95317d | 869 | =item Devel::DProf |
a5222a85 | 870 | |
7a95317d GS |
871 | Devel::DProf, a Perl source code profiler has been added. See |
872 | L<Devel::DProf> and L<dprofpp>. | |
a5222a85 | 873 | |
7a95317d | 874 | =item Devel::Peek |
a5222a85 | 875 | |
7a95317d GS |
876 | The Devel::Peek module provides access to the internal representation |
877 | of Perl variables and data. It is a data debugging tool for the XS programmer. | |
a5222a85 | 878 | |
7a95317d | 879 | =item Dumpvalue |
54195c32 | 880 | |
7a95317d | 881 | The Dumpvalue module provides screen dumps of Perl data. |
67d3893f | 882 | |
7a95317d | 883 | =item DynaLoader |
54195c32 | 884 | |
7a95317d GS |
885 | DynaLoader now supports a dl_unload_file() function on platforms that |
886 | support unloading shared objects using dlclose(). | |
a5222a85 | 887 | |
7a95317d GS |
888 | Perl can also optionally arrange to unload all extension shared objects |
889 | loaded by Perl. To enable this, build Perl with the Configure option | |
890 | C<-Accflags=-DDL_UNLOAD_ALL_AT_EXIT>. (This maybe useful if you are | |
891 | using Apache with mod_perl.) | |
a5222a85 | 892 | |
7a95317d | 893 | =item English |
a5222a85 | 894 | |
7a95317d GS |
895 | $PERL_VERSION now stands for C<$^V> (a string value) rather than for C<$]> |
896 | (a numeric value). | |
a5222a85 | 897 | |
7a95317d | 898 | =item Env |
a5222a85 | 899 | |
7a95317d GS |
900 | Env now supports accessing environment variables like PATH as array |
901 | variables. | |
a5222a85 | 902 | |
7a95317d | 903 | =item Fcntl |
a5222a85 | 904 | |
7a95317d GS |
905 | More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for |
906 | large file (more than 4GB) access (NOTE: the O_LARGEFILE is | |
907 | automatically added to sysopen() flags if large file support has been | |
908 | configured, as is the default), Free/Net/OpenBSD locking behaviour | |
909 | flags F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined | |
910 | mask of O_RDONLY, O_WRONLY, and O_RDWR. The seek()/sysseek() | |
911 | constants SEEK_SET, SEEK_CUR, and SEEK_END are available via the | |
912 | C<:seek> tag. The chmod()/stat() S_IF* constants and S_IS* functions | |
913 | are available via the C<:mode> tag. | |
a5222a85 | 914 | |
7a95317d | 915 | =item File::Compare |
a5222a85 | 916 | |
7a95317d GS |
917 | A compare_text() function has been added, which allows custom |
918 | comparison functions. See L<File::Compare>. | |
a5222a85 | 919 | |
7a95317d | 920 | =item File::Find |
a5222a85 | 921 | |
7a95317d GS |
922 | File::Find now works correctly when the wanted() function is either |
923 | autoloaded or is a symbolic reference. | |
a5222a85 | 924 | |
7a95317d GS |
925 | A bug that caused File::Find to lose track of the working directory |
926 | when pruning top-level directories has been fixed. | |
a5222a85 | 927 | |
7a95317d GS |
928 | File::Find now also supports several other options to control its |
929 | behavior. It can follow symbolic links if the C<follow> option is | |
930 | specified. Enabling the C<no_chdir> option will make File::Find skip | |
931 | changing the current directory when walking directories. The C<untaint> | |
932 | flag can be useful when running with taint checks enabled. | |
a5222a85 | 933 | |
7a95317d | 934 | See L<File::Find>. |
a5222a85 | 935 | |
7a95317d | 936 | =item File::Glob |
a5222a85 | 937 | |
7a95317d GS |
938 | This extension implements BSD-style file globbing. By default, |
939 | it will also be used for the internal implementation of the glob() | |
940 | operator. See L<File::Glob>. | |
a5222a85 | 941 | |
7a95317d | 942 | =item File::Spec |
a5222a85 | 943 | |
7a95317d GS |
944 | New methods have been added to the File::Spec module: devnull() returns |
945 | the name of the null device (/dev/null on Unix) and tmpdir() the name of | |
946 | the temp directory (normally /tmp on Unix). There are now also methods | |
947 | to convert between absolute and relative filenames: abs2rel() and | |
948 | rel2abs(). For compatibility with operating systems that specify volume | |
949 | names in file paths, the splitpath(), splitdir(), and catdir() methods | |
950 | have been added. | |
a5222a85 | 951 | |
7a95317d | 952 | =item File::Spec::Functions |
a5222a85 | 953 | |
7a95317d GS |
954 | The new File::Spec::Functions modules provides a function interface |
955 | to the File::Spec module. Allows shorthand | |
a5222a85 | 956 | |
7a95317d | 957 | $fullname = catfile($dir1, $dir2, $file); |
a5222a85 | 958 | |
7a95317d | 959 | instead of |
a398b1cd | 960 | |
7a95317d | 961 | $fullname = File::Spec->catfile($dir1, $dir2, $file); |
a398b1cd | 962 | |
7a95317d | 963 | =item Getopt::Long |
a398b1cd | 964 | |
7a95317d GS |
965 | Getopt::Long licensing has changed to allow the Perl Artistic License |
966 | as well as the GPL. It used to be GPL only, which got in the way of | |
967 | non-GPL applications that wanted to use Getopt::Long. | |
a398b1cd | 968 | |
7a95317d GS |
969 | Getopt::Long encourages the use of Pod::Usage to produce help |
970 | messages. For example: | |
a5222a85 | 971 | |
7a95317d GS |
972 | use Getopt::Long; |
973 | use Pod::Usage; | |
974 | my $man = 0; | |
975 | my $help = 0; | |
976 | GetOptions('help|?' => \$help, man => \$man) or pod2usage(2); | |
977 | pod2usage(1) if $help; | |
978 | pod2usage(-exitstatus => 0, -verbose => 2) if $man; | |
979 | ||
980 | __END__ | |
a5222a85 | 981 | |
7a95317d | 982 | =head1 NAME |
a5222a85 | 983 | |
7a95317d | 984 | sample - Using GetOpt::Long and Pod::Usage |
a5222a85 | 985 | |
7a95317d | 986 | =head1 SYNOPSIS |
a5222a85 | 987 | |
7a95317d | 988 | sample [options] [file ...] |
a5222a85 | 989 | |
7a95317d GS |
990 | Options: |
991 | -help brief help message | |
992 | -man full documentation | |
a5222a85 | 993 | |
7a95317d | 994 | =head1 OPTIONS |
a5222a85 | 995 | |
7a95317d | 996 | =over 8 |
ba8251e8 | 997 | |
7a95317d | 998 | =item B<-help> |
5fdc711f | 999 | |
7a95317d | 1000 | Print a brief help message and exits. |
5fdc711f | 1001 | |
7a95317d | 1002 | =item B<-man> |
6c67e1bb | 1003 | |
7a95317d | 1004 | Prints the manual page and exits. |
5fdc711f | 1005 | |
7a95317d | 1006 | =back |
ee3907e2 | 1007 | |
7a95317d | 1008 | =head1 DESCRIPTION |
ee3907e2 | 1009 | |
4375e838 | 1010 | B<This program> will read the given input file(s) and do something |
7a95317d | 1011 | useful with the contents thereof. |
6c67e1bb | 1012 | |
7a95317d | 1013 | =cut |
5fdc711f | 1014 | |
7a95317d | 1015 | See L<Pod::Usage> for details. |
6c67e1bb | 1016 | |
7a95317d GS |
1017 | A bug that prevented the non-option call-back <> from being |
1018 | specified as the first argument has been fixed. | |
00ad96e1 | 1019 | |
7a95317d GS |
1020 | To specify the characters < and > as option starters, use ><. Note, |
1021 | however, that changing option starters is strongly deprecated. | |
00ad96e1 | 1022 | |
7a95317d | 1023 | =item IO |
27806c82 | 1024 | |
7a95317d GS |
1025 | write() and syswrite() will now accept a single-argument |
1026 | form of the call, for consistency with Perl's syswrite(). | |
27806c82 | 1027 | |
7a95317d GS |
1028 | You can now create a TCP-based IO::Socket::INET without forcing |
1029 | a connect attempt. This allows you to configure its options | |
1030 | (like making it non-blocking) and then call connect() manually. | |
5fdc711f | 1031 | |
7a95317d GS |
1032 | A bug that prevented the IO::Socket::protocol() accessor |
1033 | from ever returning the correct value has been corrected. | |
a5222a85 | 1034 | |
7a95317d GS |
1035 | IO::Socket::connect now uses non-blocking IO instead of alarm() |
1036 | to do connect timeouts. | |
d524f05e | 1037 | |
7a95317d GS |
1038 | IO::Socket::accept now uses select() instead of alarm() for doing |
1039 | timeouts. | |
d524f05e | 1040 | |
7a95317d | 1041 | IO::Socket::INET->new now sets $! correctly on failure. $@ is |
4375e838 | 1042 | still set for backwards compatibility. |
d524f05e | 1043 | |
7a95317d | 1044 | =item JPL |
d524f05e | 1045 | |
7a95317d GS |
1046 | Java Perl Lingo is now distributed with Perl. See jpl/README |
1047 | for more information. | |
d524f05e | 1048 | |
7a95317d | 1049 | =item lib |
d524f05e | 1050 | |
7a95317d GS |
1051 | C<use lib> now weeds out any trailing duplicate entries. |
1052 | C<no lib> removes all named entries. | |
d524f05e | 1053 | |
7a95317d | 1054 | =item Math::BigInt |
d524f05e | 1055 | |
7a95317d GS |
1056 | The bitwise operations C<<< << >>>, C<<< >> >>>, C<&>, C<|>, |
1057 | and C<~> are now supported on bigints. | |
d524f05e | 1058 | |
7a95317d | 1059 | =item Math::Complex |
a5222a85 | 1060 | |
7a95317d GS |
1061 | The accessor methods Re, Im, arg, abs, rho, and theta can now also |
1062 | act as mutators (accessor $z->Re(), mutator $z->Re(3)). | |
063663a9 | 1063 | |
7a95317d GS |
1064 | The class method C<display_format> and the corresponding object method |
1065 | C<display_format>, in addition to accepting just one argument, now can | |
1066 | also accept a parameter hash. Recognized keys of a parameter hash are | |
1067 | C<"style">, which corresponds to the old one parameter case, and two | |
1068 | new parameters: C<"format">, which is a printf()-style format string | |
1069 | (defaults usually to C<"%.15g">, you can revert to the default by | |
1070 | setting the format string to C<undef>) used for both parts of a | |
1071 | complex number, and C<"polar_pretty_print"> (defaults to true), | |
1072 | which controls whether an attempt is made to try to recognize small | |
1073 | multiples and rationals of pi (2pi, pi/2) at the argument (angle) of a | |
1074 | polar complex number. | |
063663a9 | 1075 | |
7a95317d GS |
1076 | The potentially disruptive change is that in list context both methods |
1077 | now I<return the parameter hash>, instead of only the value of the | |
1078 | C<"style"> parameter. | |
063663a9 | 1079 | |
7a95317d | 1080 | =item Math::Trig |
a5222a85 | 1081 | |
7a95317d GS |
1082 | A little bit of radial trigonometry (cylindrical and spherical), |
1083 | radial coordinate conversions, and the great circle distance were added. | |
c93fa817 | 1084 | |
7a95317d | 1085 | =item Pod::Parser, Pod::InputObjects |
c93fa817 | 1086 | |
7a95317d GS |
1087 | Pod::Parser is a base class for parsing and selecting sections of |
1088 | pod documentation from an input stream. This module takes care of | |
1089 | identifying pod paragraphs and commands in the input and hands off the | |
1090 | parsed paragraphs and commands to user-defined methods which are free | |
1091 | to interpret or translate them as they see fit. | |
c93fa817 | 1092 | |
7a95317d GS |
1093 | Pod::InputObjects defines some input objects needed by Pod::Parser, and |
1094 | for advanced users of Pod::Parser that need more about a command besides | |
1095 | its name and text. | |
c93fa817 | 1096 | |
7a95317d GS |
1097 | As of release 5.6.0 of Perl, Pod::Parser is now the officially sanctioned |
1098 | "base parser code" recommended for use by all pod2xxx translators. | |
1099 | Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted | |
1100 | to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already | |
1101 | underway. For any questions or comments about pod parsing and translating | |
1102 | issues and utilities, please use the pod-people@perl.org mailing list. | |
c93fa817 | 1103 | |
7a95317d | 1104 | For further information, please see L<Pod::Parser> and L<Pod::InputObjects>. |
c93fa817 | 1105 | |
7a95317d | 1106 | =item Pod::Checker, podchecker |
c93fa817 | 1107 | |
7a95317d GS |
1108 | This utility checks pod files for correct syntax, according to |
1109 | L<perlpod>. Obvious errors are flagged as such, while warnings are | |
1110 | printed for mistakes that can be handled gracefully. The checklist is | |
1111 | not complete yet. See L<Pod::Checker>. | |
c93fa817 | 1112 | |
7a95317d | 1113 | =item Pod::ParseUtils, Pod::Find |
c93fa817 | 1114 | |
7a95317d GS |
1115 | These modules provide a set of gizmos that are useful mainly for pod |
1116 | translators. L<Pod::Find|Pod::Find> traverses directory structures and | |
1117 | returns found pod files, along with their canonical names (like | |
1118 | C<File::Spec::Unix>). L<Pod::ParseUtils|Pod::ParseUtils> contains | |
1119 | B<Pod::List> (useful for storing pod list information), B<Pod::Hyperlink> | |
1120 | (for parsing the contents of C<LE<lt>E<gt>> sequences) and B<Pod::Cache> | |
1121 | (for caching information about pod files, e.g., link nodes). | |
a5222a85 | 1122 | |
7a95317d | 1123 | =item Pod::Select, podselect |
a5222a85 | 1124 | |
7a95317d GS |
1125 | Pod::Select is a subclass of Pod::Parser which provides a function |
1126 | named "podselect()" to filter out user-specified sections of raw pod | |
1127 | documentation from an input stream. podselect is a script that provides | |
1128 | access to Pod::Select from other scripts to be used as a filter. | |
1129 | See L<Pod::Select>. | |
a5222a85 | 1130 | |
7a95317d | 1131 | =item Pod::Usage, pod2usage |
a5222a85 | 1132 | |
7a95317d GS |
1133 | Pod::Usage provides the function "pod2usage()" to print usage messages for |
1134 | a Perl script based on its embedded pod documentation. The pod2usage() | |
1135 | function is generally useful to all script authors since it lets them | |
1136 | write and maintain a single source (the pods) for documentation, thus | |
1137 | removing the need to create and maintain redundant usage message text | |
1138 | consisting of information already in the pods. | |
a5222a85 | 1139 | |
7a95317d GS |
1140 | There is also a pod2usage script which can be used from other kinds of |
1141 | scripts to print usage messages from pods (even for non-Perl scripts | |
1142 | with pods embedded in comments). | |
a5222a85 | 1143 | |
7a95317d | 1144 | For details and examples, please see L<Pod::Usage>. |
a5222a85 | 1145 | |
7a95317d | 1146 | =item Pod::Text and Pod::Man |
a5222a85 | 1147 | |
7a95317d GS |
1148 | Pod::Text has been rewritten to use Pod::Parser. While pod2text() is |
1149 | still available for backwards compatibility, the module now has a new | |
1150 | preferred interface. See L<Pod::Text> for the details. The new Pod::Text | |
1151 | module is easily subclassed for tweaks to the output, and two such | |
1152 | subclasses (Pod::Text::Termcap for man-page-style bold and underlining | |
1153 | using termcap information, and Pod::Text::Color for markup with ANSI color | |
1154 | sequences) are now standard. | |
a5222a85 | 1155 | |
7a95317d GS |
1156 | pod2man has been turned into a module, Pod::Man, which also uses |
1157 | Pod::Parser. In the process, several outstanding bugs related to quotes | |
1158 | in section headers, quoting of code escapes, and nested lists have been | |
1159 | fixed. pod2man is now a wrapper script around this module. | |
42b8b86c | 1160 | |
7a95317d | 1161 | =item SDBM_File |
a5222a85 | 1162 | |
7a95317d GS |
1163 | An EXISTS method has been added to this module (and sdbm_exists() has |
1164 | been added to the underlying sdbm library), so one can now call exists | |
1165 | on an SDBM_File tied hash and get the correct result, rather than a | |
1166 | runtime error. | |
883d36a6 | 1167 | |
7a95317d GS |
1168 | A bug that may have caused data loss when more than one disk block |
1169 | happens to be read from the database in a single FETCH() has been | |
1170 | fixed. | |
c39cd008 | 1171 | |
7a95317d | 1172 | =item Sys::Syslog |
16070b82 | 1173 | |
7a95317d GS |
1174 | Sys::Syslog now uses XSUBs to access facilities from syslog.h so it |
1175 | no longer requires syslog.ph to exist. | |
6c67e1bb | 1176 | |
7a95317d | 1177 | =item Sys::Hostname |
6c67e1bb | 1178 | |
7a95317d GS |
1179 | Sys::Hostname now uses XSUBs to call the C library's gethostname() or |
1180 | uname() if they exist. | |
09bef843 | 1181 | |
7a95317d | 1182 | =item Term::ANSIColor |
09bef843 | 1183 | |
7a95317d GS |
1184 | Term::ANSIColor is a very simple module to provide easy and readable |
1185 | access to the ANSI color and highlighting escape sequences, supported by | |
1186 | most ANSI terminal emulators. It is now included standard. | |
2675e62c | 1187 | |
7a95317d | 1188 | =item Time::Local |
2675e62c | 1189 | |
7a95317d GS |
1190 | The timelocal() and timegm() functions used to silently return bogus |
1191 | results when the date fell outside the machine's integer range. They | |
1192 | now consistently croak() if the date falls in an unsupported range. | |
2675e62c | 1193 | |
7a95317d | 1194 | =item Win32 |
2675e62c | 1195 | |
7a95317d GS |
1196 | The error return value in list context has been changed for all functions |
1197 | that return a list of values. Previously these functions returned a list | |
1198 | with a single element C<undef> if an error occurred. Now these functions | |
1199 | return the empty list in these situations. This applies to the following | |
1200 | functions: | |
6c67e1bb | 1201 | |
7a95317d GS |
1202 | Win32::FsType |
1203 | Win32::GetOSVersion | |
14218588 | 1204 | |
7a95317d GS |
1205 | The remaining functions are unchanged and continue to return C<undef> on |
1206 | error even in list context. | |
6c67e1bb | 1207 | |
7a95317d GS |
1208 | The Win32::SetLastError(ERROR) function has been added as a complement |
1209 | to the Win32::GetLastError() function. | |
6c67e1bb | 1210 | |
7a95317d GS |
1211 | The new Win32::GetFullPathName(FILENAME) returns the full absolute |
1212 | pathname for FILENAME in scalar context. In list context it returns | |
1213 | a two-element list containing the fully qualified directory name and | |
1214 | the filename. See L<Win32>. | |
6c67e1bb | 1215 | |
7a95317d | 1216 | =item XSLoader |
6c67e1bb | 1217 | |
7a95317d GS |
1218 | The XSLoader extension is a simpler alternative to DynaLoader. |
1219 | See L<XSLoader>. | |
6c67e1bb | 1220 | |
7a95317d | 1221 | =item DBM Filters |
6c67e1bb | 1222 | |
7a95317d GS |
1223 | A new feature called "DBM Filters" has been added to all the |
1224 | DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File. | |
1225 | DBM Filters add four new methods to each DBM module: | |
6c67e1bb | 1226 | |
7a95317d GS |
1227 | filter_store_key |
1228 | filter_store_value | |
1229 | filter_fetch_key | |
1230 | filter_fetch_value | |
6c67e1bb | 1231 | |
7a95317d GS |
1232 | These can be used to filter key-value pairs before the pairs are |
1233 | written to the database or just after they are read from the database. | |
1234 | See L<perldbmfilter> for further information. | |
09bef843 | 1235 | |
7a95317d | 1236 | =back |
09bef843 | 1237 | |
7a95317d | 1238 | =head2 Pragmata |
6c67e1bb | 1239 | |
7a95317d GS |
1240 | C<use attrs> is now obsolete, and is only provided for |
1241 | backward-compatibility. It's been replaced by the C<sub : attributes> | |
1242 | syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>. | |
6c67e1bb | 1243 | |
7a95317d GS |
1244 | Lexical warnings pragma, C<use warnings;>, to control optional warnings. |
1245 | See L<perllexwarn>. | |
6c67e1bb | 1246 | |
7a95317d GS |
1247 | C<use filetest> to control the behaviour of filetests (C<-r> C<-w> |
1248 | ...). Currently only one subpragma implemented, "use filetest | |
1249 | 'access';", that uses access(2) or equivalent to check permissions | |
1250 | instead of using stat(2) as usual. This matters in filesystems | |
1251 | where there are ACLs (access control lists): the stat(2) might lie, | |
1252 | but access(2) knows better. | |
6c67e1bb | 1253 | |
7a95317d GS |
1254 | The C<open> pragma can be used to specify default disciplines for |
1255 | handle constructors (e.g. open()) and for qx//. The two | |
1256 | pseudo-disciplines C<:raw> and C<:crlf> are currently supported on | |
1257 | DOS-derivative platforms (i.e. where binmode is not a no-op). | |
1258 | See also L</"binmode() can be used to set :crlf and :raw modes">. | |
afebc493 | 1259 | |
7a95317d | 1260 | =head1 Utility Changes |
afebc493 | 1261 | |
7a95317d | 1262 | =head2 dprofpp |
e02fdbd2 | 1263 | |
7a95317d GS |
1264 | C<dprofpp> is used to display profile data generated using C<Devel::DProf>. |
1265 | See L<dprofpp>. | |
ba8251e8 | 1266 | |
7a95317d | 1267 | =head2 find2perl |
3e8c4fa0 | 1268 | |
7a95317d GS |
1269 | The C<find2perl> utility now uses the enhanced features of the File::Find |
1270 | module. The -depth and -follow options are supported. Pod documentation | |
1271 | is also included in the script. | |
b7d8191e | 1272 | |
7a95317d | 1273 | =head2 h2xs |
09bef843 | 1274 | |
7a95317d GS |
1275 | The C<h2xs> tool can now work in conjunction with C<C::Scan> (available |
1276 | from CPAN) to automatically parse real-life header files. The C<-M>, | |
1277 | C<-a>, C<-k>, and C<-o> options are new. | |
09bef843 | 1278 | |
7a95317d | 1279 | =head2 perlcc |
a5222a85 | 1280 | |
7a95317d GS |
1281 | C<perlcc> now supports the C and Bytecode backends. By default, |
1282 | it generates output from the simple C backend rather than the | |
1283 | optimized C backend. | |
501fbaef | 1284 | |
7a95317d | 1285 | Support for non-Unix platforms has been improved. |
a5222a85 | 1286 | |
7a95317d | 1287 | =head2 perldoc |
f29c64d6 | 1288 | |
7a95317d GS |
1289 | C<perldoc> has been reworked to avoid possible security holes. |
1290 | It will not by default let itself be run as the superuser, but you | |
1291 | may still use the B<-U> switch to try to make it drop privileges | |
1292 | first. | |
f29c64d6 | 1293 | |
7a95317d | 1294 | =head2 The Perl Debugger |
a5222a85 | 1295 | |
7a95317d GS |
1296 | Many bug fixes and enhancements were added to F<perl5db.pl>, the |
1297 | Perl debugger. The help documentation was rearranged. New commands | |
1298 | include C<< < ? >>, C<< > ? >>, and C<< { ? >> to list out current | |
1299 | actions, C<man I<docpage>> to run your doc viewer on some perl | |
1300 | docset, and support for quoted options. The help information was | |
1301 | rearranged, and should be viewable once again if you're using B<less> | |
1302 | as your pager. A serious security hole was plugged--you should | |
1303 | immediately remove all older versions of the Perl debugger as | |
1304 | installed in previous releases, all the way back to perl3, from | |
1305 | your system to avoid being bitten by this. | |
83763826 | 1306 | |
7a95317d | 1307 | =head1 Improved Documentation |
83763826 | 1308 | |
7a95317d GS |
1309 | Many of the platform-specific README files are now part of the perl |
1310 | installation. See L<perl> for the complete list. | |
a5222a85 | 1311 | |
7a95317d | 1312 | =over 4 |
a5222a85 | 1313 | |
7a95317d | 1314 | =item perlapi.pod |
a5222a85 | 1315 | |
7a95317d | 1316 | The official list of public Perl API functions. |
a5222a85 | 1317 | |
7a95317d | 1318 | =item perlboot.pod |
a5222a85 | 1319 | |
7a95317d | 1320 | A tutorial for beginners on object-oriented Perl. |
0f1923bd | 1321 | |
7a95317d | 1322 | =item perlcompile.pod |
a5222a85 | 1323 | |
7a95317d | 1324 | An introduction to using the Perl Compiler suite. |
a5222a85 | 1325 | |
7a95317d | 1326 | =item perldbmfilter.pod |
a5222a85 | 1327 | |
7a95317d | 1328 | A howto document on using the DBM filter facility. |
a5222a85 | 1329 | |
7a95317d | 1330 | =item perldebug.pod |
a5222a85 | 1331 | |
7a95317d GS |
1332 | All material unrelated to running the Perl debugger, plus all |
1333 | low-level guts-like details that risked crushing the casual user | |
1334 | of the debugger, have been relocated from the old manpage to the | |
1335 | next entry below. | |
f29c64d6 | 1336 | |
7a95317d | 1337 | =item perldebguts.pod |
f29c64d6 | 1338 | |
7a95317d GS |
1339 | This new manpage contains excessively low-level material not related |
1340 | to the Perl debugger, but slightly related to debugging Perl itself. | |
1341 | It also contains some arcane internal details of how the debugging | |
1342 | process works that may only be of interest to developers of Perl | |
1343 | debuggers. | |
b7d8191e | 1344 | |
7a95317d | 1345 | =item perlfork.pod |
b7d8191e | 1346 | |
7a95317d | 1347 | Notes on the fork() emulation currently available for the Windows platform. |
23d2500b | 1348 | |
7a95317d | 1349 | =item perlfilter.pod |
23d2500b | 1350 | |
7a95317d | 1351 | An introduction to writing Perl source filters. |
23d2500b | 1352 | |
7a95317d | 1353 | =item perlhack.pod |
b7d8191e | 1354 | |
7a95317d | 1355 | Some guidelines for hacking the Perl source code. |
54e82ce5 | 1356 | |
7a95317d | 1357 | =item perlintern.pod |
155776c0 | 1358 | |
7a95317d GS |
1359 | A list of internal functions in the Perl source code. |
1360 | (List is currently empty.) | |
155776c0 | 1361 | |
7a95317d | 1362 | =item perllexwarn.pod |
155776c0 | 1363 | |
7a95317d GS |
1364 | Introduction and reference information about lexically scoped |
1365 | warning categories. | |
155776c0 | 1366 | |
7a95317d | 1367 | =item perlnumber.pod |
b7d8191e | 1368 | |
7a95317d | 1369 | Detailed information about numbers as they are represented in Perl. |
54e82ce5 | 1370 | |
7a95317d | 1371 | =item perlopentut.pod |
54e82ce5 | 1372 | |
7a95317d | 1373 | A tutorial on using open() effectively. |
54e82ce5 | 1374 | |
7a95317d | 1375 | =item perlreftut.pod |
54e82ce5 | 1376 | |
7a95317d | 1377 | A tutorial that introduces the essentials of references. |
54e82ce5 | 1378 | |
7a95317d | 1379 | =item perltootc.pod |
a5222a85 | 1380 | |
7a95317d | 1381 | A tutorial on managing class data for object modules. |
f505c983 | 1382 | |
7a95317d | 1383 | =item perltodo.pod |
f505c983 | 1384 | |
7a95317d GS |
1385 | Discussion of the most often wanted features that may someday be |
1386 | supported in Perl. | |
44dcb63b | 1387 | |
7a95317d | 1388 | =item perlunicode.pod |
44dcb63b | 1389 | |
7a95317d | 1390 | An introduction to Unicode support features in Perl. |
2675e62c | 1391 | |
7a95317d | 1392 | =back |
2675e62c | 1393 | |
7a95317d | 1394 | =head1 Performance enhancements |
b7d8191e | 1395 | |
7a95317d | 1396 | =head2 Simple sort() using { $a <=> $b } and the like are optimized |
b7d8191e | 1397 | |
7a95317d GS |
1398 | Many common sort() operations using a simple inlined block are now |
1399 | optimized for faster performance. | |
a5222a85 | 1400 | |
7a95317d | 1401 | =head2 Optimized assignments to lexical variables |
a5222a85 | 1402 | |
7a95317d GS |
1403 | Certain operations in the RHS of assignment statements have been |
1404 | optimized to directly set the lexical variable on the LHS, | |
1405 | eliminating redundant copying overheads. | |
a5222a85 | 1406 | |
7a95317d | 1407 | =head2 Faster subroutine calls |
a5222a85 | 1408 | |
7a95317d GS |
1409 | Minor changes in how subroutine calls are handled internally |
1410 | provide marginal improvements in performance. | |
a5222a85 | 1411 | |
7a95317d | 1412 | =item delete(), each(), values() and hash iteration are faster |
81793b90 | 1413 | |
7a95317d GS |
1414 | The hash values returned by delete(), each(), values() and hashes in a |
1415 | list context are the actual values in the hash, instead of copies. | |
1416 | This results in significantly better performance, because it eliminates | |
1417 | needless copying in most situations. | |
81793b90 | 1418 | |
7a95317d | 1419 | =head1 Installation and Configuration Improvements |
becf2bd3 | 1420 | |
7a95317d | 1421 | =head2 -Dusethreads means something different |
becf2bd3 | 1422 | |
7a95317d GS |
1423 | The -Dusethreads flag now enables the experimental interpreter-based thread |
1424 | support by default. To get the flavor of experimental threads that was in | |
1425 | 5.005 instead, you need to run Configure with "-Dusethreads -Duse5005threads". | |
f505c983 | 1426 | |
7a95317d GS |
1427 | As of v5.6.0, interpreter-threads support is still lacking a way to |
1428 | create new threads from Perl (i.e., C<use Thread;> will not work with | |
1429 | interpreter threads). C<use Thread;> continues to be available when you | |
1430 | specify the -Duse5005threads option to Configure, bugs and all. | |
f505c983 | 1431 | |
7a95317d GS |
1432 | NOTE: Support for threads continues to be an experimental feature. |
1433 | Interfaces and implementation are subject to sudden and drastic changes. | |
f505c983 | 1434 | |
7a95317d | 1435 | =head2 New Configure flags |
f505c983 | 1436 | |
7a95317d GS |
1437 | The following new flags may be enabled on the Configure command line |
1438 | by running Configure with C<-Dflag>. | |
f505c983 | 1439 | |
7a95317d GS |
1440 | usemultiplicity |
1441 | usethreads useithreads (new interpreter threads: no Perl API yet) | |
1442 | usethreads use5005threads (threads as they were in 5.005) | |
f505c983 | 1443 | |
7a95317d GS |
1444 | use64bitint (equal to now deprecated 'use64bits') |
1445 | use64bitall | |
f505c983 | 1446 | |
7a95317d GS |
1447 | uselongdouble |
1448 | usemorebits | |
1449 | uselargefiles | |
1450 | usesocks (only SOCKS v5 supported) | |
a5222a85 | 1451 | |
7a95317d | 1452 | =head2 Threadedness and 64-bitness now more daring |
c6edd1b7 | 1453 | |
7a95317d GS |
1454 | The Configure options enabling the use of threads and the use of |
1455 | 64-bitness are now more daring in the sense that they no more have an | |
1456 | explicit list of operating systems of known threads/64-bit | |
1457 | capabilities. In other words: if your operating system has the | |
1458 | necessary APIs and datatypes, you should be able just to go ahead and | |
1459 | use them, for threads by Configure -Dusethreads, and for 64 bits | |
1460 | either explicitly by Configure -Duse64bitint or implicitly if your | |
1461 | system has 64-bit wide datatypes. See also L<"64-bit support">. | |
c6edd1b7 | 1462 | |
7a95317d | 1463 | =head2 Long Doubles |
c6edd1b7 | 1464 | |
7a95317d GS |
1465 | Some platforms have "long doubles", floating point numbers of even |
1466 | larger range than ordinary "doubles". To enable using long doubles for | |
1467 | Perl's scalars, use -Duselongdouble. | |
c6edd1b7 | 1468 | |
7a95317d | 1469 | =head2 -Dusemorebits |
c6edd1b7 | 1470 | |
7a95317d GS |
1471 | You can enable both -Duse64bitint and -Duselongdouble with -Dusemorebits. |
1472 | See also L<"64-bit support">. | |
c6edd1b7 | 1473 | |
7a95317d | 1474 | =head2 -Duselargefiles |
c6edd1b7 | 1475 | |
7a95317d GS |
1476 | Some platforms support system APIs that are capable of handling large files |
1477 | (typically, files larger than two gigabytes). Perl will try to use these | |
1478 | APIs if you ask for -Duselargefiles. | |
c6edd1b7 | 1479 | |
7a95317d | 1480 | See L<"Large file support"> for more information. |
c6edd1b7 | 1481 | |
7a95317d | 1482 | =head2 installusrbinperl |
c6edd1b7 | 1483 | |
7a95317d GS |
1484 | You can use "Configure -Uinstallusrbinperl" which causes installperl |
1485 | to skip installing perl also as /usr/bin/perl. This is useful if you | |
1486 | prefer not to modify /usr/bin for some reason or another but harmful | |
1487 | because many scripts assume to find Perl in /usr/bin/perl. | |
c6edd1b7 | 1488 | |
7a95317d | 1489 | =head2 SOCKS support |
c6edd1b7 | 1490 | |
7a95317d GS |
1491 | You can use "Configure -Dusesocks" which causes Perl to probe |
1492 | for the SOCKS proxy protocol library (v5, not v4). For more information | |
1493 | on SOCKS, see: | |
c6edd1b7 | 1494 | |
7a95317d | 1495 | http://www.socks.nec.com/ |
c6edd1b7 | 1496 | |
7a95317d | 1497 | =head2 C<-A> flag |
c6edd1b7 | 1498 | |
7a95317d GS |
1499 | You can "post-edit" the Configure variables using the Configure C<-A> |
1500 | switch. The editing happens immediately after the platform specific | |
1501 | hints files have been processed but before the actual configuration | |
1502 | process starts. Run C<Configure -h> to find out the full C<-A> syntax. | |
c6edd1b7 | 1503 | |
7a95317d | 1504 | =head2 Enhanced Installation Directories |
c6edd1b7 | 1505 | |
7a95317d GS |
1506 | The installation structure has been enriched to improve the support |
1507 | for maintaining multiple versions of perl, to provide locations for | |
1508 | vendor-supplied modules, scripts, and manpages, and to ease maintenance | |
1509 | of locally-added modules, scripts, and manpages. See the section on | |
1510 | Installation Directories in the INSTALL file for complete details. | |
1511 | For most users building and installing from source, the defaults should | |
1512 | be fine. | |
c6edd1b7 | 1513 | |
7a95317d GS |
1514 | If you previously used C<Configure -Dsitelib> or C<-Dsitearch> to set |
1515 | special values for library directories, you might wish to consider using | |
1516 | the new C<-Dsiteprefix> setting instead. Also, if you wish to re-use a | |
1517 | config.sh file from an earlier version of perl, you should be sure to | |
1518 | check that Configure makes sensible choices for the new directories. | |
1519 | See INSTALL for complete details. | |
c6edd1b7 | 1520 | |
7a95317d | 1521 | =head1 Platform specific changes |
c6edd1b7 | 1522 | |
7a95317d | 1523 | =head2 Supported platforms |
c6edd1b7 | 1524 | |
7a95317d | 1525 | =over 4 |
a5222a85 | 1526 | |
7a95317d | 1527 | =item * |
a5222a85 | 1528 | |
7a95317d GS |
1529 | The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread |
1530 | extension. | |
36f31b50 | 1531 | |
7a95317d | 1532 | =item * |
36f31b50 | 1533 | |
7a95317d | 1534 | GNU/Hurd is now supported. |
a5222a85 | 1535 | |
7a95317d | 1536 | =item * |
a5222a85 | 1537 | |
7a95317d | 1538 | Rhapsody/Darwin is now supported. |
883d36a6 | 1539 | |
7a95317d | 1540 | =item * |
883d36a6 | 1541 | |
106325ad | 1542 | EPOC is now supported (on Psion 5). |
e16b8f49 | 1543 | |
7a95317d | 1544 | =item * |
e16b8f49 | 1545 | |
7a95317d | 1546 | The cygwin port (formerly cygwin32) has been greatly improved. |
7711098a | 1547 | |
7a95317d | 1548 | =back |
b7d8191e | 1549 | |
7a95317d | 1550 | =head2 DOS |
16357284 | 1551 | |
7a95317d | 1552 | =over 4 |
16357284 | 1553 | |
7a95317d | 1554 | =item * |
b7d8191e | 1555 | |
7a95317d | 1556 | Perl now works with djgpp 2.02 (and 2.03 alpha). |
b7d8191e | 1557 | |
7a95317d | 1558 | =item * |
d4629d6a | 1559 | |
7a95317d | 1560 | Environment variable names are not converted to uppercase any more. |
d4629d6a | 1561 | |
7a95317d | 1562 | =item * |
d4629d6a | 1563 | |
7a95317d | 1564 | Incorrect exit codes from backticks have been fixed. |
d4629d6a | 1565 | |
7a95317d | 1566 | =item * |
d4629d6a | 1567 | |
7a95317d | 1568 | This port continues to use its own builtin globbing (not File::Glob). |
d4629d6a | 1569 | |
7a95317d | 1570 | =back |
d4629d6a | 1571 | |
7a95317d | 1572 | =head2 OS390 (OpenEdition MVS) |
d4629d6a | 1573 | |
7a95317d GS |
1574 | Support for this EBCDIC platform has not been renewed in this release. |
1575 | There are difficulties in reconciling Perl's standardization on UTF-8 | |
1576 | as its internal representation for characters with the EBCDIC character | |
1577 | set, because the two are incompatible. | |
d4629d6a | 1578 | |
7a95317d GS |
1579 | It is unclear whether future versions will renew support for this |
1580 | platform, but the possibility exists. | |
d4629d6a | 1581 | |
7a95317d | 1582 | =head2 VMS |
d4629d6a | 1583 | |
7a95317d | 1584 | Numerous revisions and extensions to configuration, build, testing, and |
4375e838 | 1585 | installation process to accommodate core changes and VMS-specific options. |
d4629d6a | 1586 | |
7a95317d GS |
1587 | Expand %ENV-handling code to allow runtime mapping to logical names, |
1588 | CLI symbols, and CRTL environ array. | |
d4629d6a | 1589 | |
7a95317d GS |
1590 | Extension of subprocess invocation code to accept filespecs as command |
1591 | "verbs". | |
a5222a85 | 1592 | |
7a95317d GS |
1593 | Add to Perl command line processing the ability to use default file types and |
1594 | to recognize Unix-style C<2E<gt>&1>. | |
a5222a85 | 1595 | |
7a95317d | 1596 | Expansion of File::Spec::VMS routines, and integration into ExtUtils::MM_VMS. |
a5222a85 | 1597 | |
7a95317d GS |
1598 | Extension of ExtUtils::MM_VMS to handle complex extensions more flexibly. |
1599 | ||
1600 | Barewords at start of Unix-syntax paths may be treated as text rather than | |
1601 | only as logical names. | |
1602 | ||
1603 | Optional secure translation of several logical names used internally by Perl. | |
1604 | ||
1605 | Miscellaneous bugfixing and porting of new core code to VMS. | |
e3e5e1ea | 1606 | |
7a95317d GS |
1607 | Thanks are gladly extended to the many people who have contributed VMS |
1608 | patches, testing, and ideas. | |
a5222a85 | 1609 | |
7a95317d | 1610 | =head2 Win32 |
f4b9d880 | 1611 | |
7a95317d GS |
1612 | Perl can now emulate fork() internally, using multiple interpreters running |
1613 | in different concurrent threads. This support must be enabled at build | |
1614 | time. See L<perlfork> for detailed information. | |
f4b9d880 | 1615 | |
7a95317d GS |
1616 | When given a pathname that consists only of a drivename, such as C<A:>, |
1617 | opendir() and stat() now use the current working directory for the drive | |
1618 | rather than the drive root. | |
a5222a85 | 1619 | |
7a95317d GS |
1620 | The builtin XSUB functions in the Win32:: namespace are documented. See |
1621 | L<Win32>. | |
8ce86de8 | 1622 | |
7a95317d | 1623 | $^X now contains the full path name of the running executable. |
8ce86de8 | 1624 | |
7a95317d GS |
1625 | A Win32::GetLongPathName() function is provided to complement |
1626 | Win32::GetFullPathName() and Win32::GetShortPathName(). See L<Win32>. | |
f91101c9 | 1627 | |
7a95317d | 1628 | POSIX::uname() is supported. |
f91101c9 | 1629 | |
7a95317d GS |
1630 | system(1,...) now returns true process IDs rather than process |
1631 | handles. kill() accepts any real process id, rather than strictly | |
1632 | return values from system(1,...). | |
e3e5e1ea | 1633 | |
7a95317d GS |
1634 | For better compatibility with Unix, C<kill(0, $pid)> can now be used to |
1635 | test whether a process exists. | |
e3e5e1ea | 1636 | |
7a95317d | 1637 | The C<Shell> module is supported. |
06ef4121 | 1638 | |
7a95317d GS |
1639 | Better support for building Perl under command.com in Windows 95 |
1640 | has been added. | |
06ef4121 | 1641 | |
7a95317d GS |
1642 | Scripts are read in binary mode by default to allow ByteLoader (and |
1643 | the filter mechanism in general) to work properly. For compatibility, | |
1644 | the DATA filehandle will be set to text mode if a carriage return is | |
1645 | detected at the end of the line containing the __END__ or __DATA__ | |
1646 | token; if not, the DATA filehandle will be left open in binary mode. | |
1647 | Earlier versions always opened the DATA filehandle in text mode. | |
8fe0a5c4 | 1648 | |
7a95317d GS |
1649 | The glob() operator is implemented via the C<File::Glob> extension, |
1650 | which supports glob syntax of the C shell. This increases the flexibility | |
1651 | of the glob() operator, but there may be compatibility issues for | |
1652 | programs that relied on the older globbing syntax. If you want to | |
1653 | preserve compatibility with the older syntax, you might want to run | |
1654 | perl with C<-MFile::DosGlob>. For details and compatibility information, | |
1655 | see L<File::Glob>. | |
8fe0a5c4 | 1656 | |
7a95317d | 1657 | =head1 Significant bug fixes |
8fe0a5c4 | 1658 | |
7a95317d | 1659 | =head2 <HANDLE> on empty files |
8fe0a5c4 | 1660 | |
7a95317d GS |
1661 | With C<$/> set to C<undef>, "slurping" an empty file returns a string of |
1662 | zero length (instead of C<undef>, as it used to) the first time the | |
1663 | HANDLE is read after C<$/> is set to C<undef>. Further reads yield | |
1664 | C<undef>. | |
8fe0a5c4 | 1665 | |
7a95317d GS |
1666 | This means that the following will append "foo" to an empty file (it used |
1667 | to do nothing): | |
8fe0a5c4 | 1668 | |
7a95317d | 1669 | perl -0777 -pi -e 's/^/foo/' empty_file |
23d2500b | 1670 | |
7a95317d | 1671 | The behaviour of: |
23d2500b | 1672 | |
7a95317d | 1673 | perl -pi -e 's/^/foo/' empty_file |
9fe6733a | 1674 | |
7a95317d | 1675 | is unchanged (it continues to leave the file empty). |
9fe6733a | 1676 | |
7a95317d | 1677 | =head2 C<eval '...'> improvements |
9fe6733a | 1678 | |
7a95317d GS |
1679 | Line numbers (as reflected by caller() and most diagnostics) within |
1680 | C<eval '...'> were often incorrect where here documents were involved. | |
1681 | This has been corrected. | |
9fe6733a | 1682 | |
7a95317d GS |
1683 | Lexical lookups for variables appearing in C<eval '...'> within |
1684 | functions that were themselves called within an C<eval '...'> were | |
1685 | searching the wrong place for lexicals. The lexical search now | |
1686 | correctly ends at the subroutine's block boundary. | |
3e8c4fa0 | 1687 | |
7a95317d GS |
1688 | The use of C<return> within C<eval {...}> caused $@ not to be reset |
1689 | correctly when no exception occurred within the eval. This has | |
1690 | been fixed. | |
3e8c4fa0 | 1691 | |
7a95317d GS |
1692 | Parsing of here documents used to be flawed when they appeared as |
1693 | the replacement expression in C<eval 's/.../.../e'>. This has | |
1694 | been fixed. | |
09bef843 | 1695 | |
7a95317d | 1696 | =head2 All compilation errors are true errors |
6c67e1bb | 1697 | |
4375e838 | 1698 | Some "errors" encountered at compile time were by necessity |
7a95317d GS |
1699 | generated as warnings followed by eventual termination of the |
1700 | program. This enabled more such errors to be reported in a | |
1701 | single run, rather than causing a hard stop at the first error | |
1702 | that was encountered. | |
6c67e1bb | 1703 | |
7a95317d GS |
1704 | The mechanism for reporting such errors has been reimplemented |
1705 | to queue compile-time errors and report them at the end of the | |
1706 | compilation as true errors rather than as warnings. This fixes | |
1707 | cases where error messages leaked through in the form of warnings | |
1708 | when code was compiled at run time using C<eval STRING>, and | |
1709 | also allows such errors to be reliably trapped using C<eval "...">. | |
ba8251e8 | 1710 | |
7a95317d | 1711 | =head2 Implicitly closed filehandles are safer |
a5222a85 | 1712 | |
7a95317d GS |
1713 | Sometimes implicitly closed filehandles (as when they are localized, |
1714 | and Perl automatically closes them on exiting the scope) could | |
1715 | inadvertently set $? or $!. This has been corrected. | |
a5222a85 | 1716 | |
a5222a85 | 1717 | |
7a95317d | 1718 | =head2 Behavior of list slices is more consistent |
055fd3a9 | 1719 | |
7a95317d GS |
1720 | When taking a slice of a literal list (as opposed to a slice of |
1721 | an array or hash), Perl used to return an empty list if the | |
1722 | result happened to be composed of all undef values. | |
055fd3a9 | 1723 | |
7a95317d GS |
1724 | The new behavior is to produce an empty list if (and only if) |
1725 | the original list was empty. Consider the following example: | |
055fd3a9 | 1726 | |
7a95317d | 1727 | @a = (1,undef,undef,2)[2,1,2]; |
055fd3a9 | 1728 | |
7a95317d GS |
1729 | The old behavior would have resulted in @a having no elements. |
1730 | The new behavior ensures it has three undefined elements. | |
ba8251e8 | 1731 | |
7a95317d GS |
1732 | Note in particular that the behavior of slices of the following |
1733 | cases remains unchanged: | |
5fdc711f | 1734 | |
7a95317d GS |
1735 | @a = ()[1,2]; |
1736 | @a = (getpwent)[7,0]; | |
1737 | @a = (anything_returning_empty_list())[2,1,2]; | |
1738 | @a = @b[2,1,2]; | |
1739 | @a = @c{'a','b','c'}; | |
954c1994 | 1740 | |
7a95317d | 1741 | See L<perldata>. |
954c1994 | 1742 | |
7a95317d | 1743 | =head2 C<(\$)> prototype and C<$foo{a}> |
883d36a6 | 1744 | |
7a95317d GS |
1745 | A scalar reference prototype now correctly allows a hash or |
1746 | array element in that slot. | |
883d36a6 | 1747 | |
7a95317d | 1748 | =head2 C<goto &sub> and AUTOLOAD |
055fd3a9 | 1749 | |
7a95317d GS |
1750 | The C<goto &sub> construct works correctly when C<&sub> happens |
1751 | to be autoloaded. | |
055fd3a9 | 1752 | |
7a95317d | 1753 | =head2 C<-bareword> allowed under C<use integer> |
055fd3a9 | 1754 | |
7a95317d GS |
1755 | The autoquoting of barewords preceded by C<-> did not work |
1756 | in prior versions when the C<integer> pragma was enabled. | |
1757 | This has been fixed. | |
055fd3a9 | 1758 | |
7a95317d | 1759 | =head2 Failures in DESTROY() |
c7c04614 | 1760 | |
7a95317d GS |
1761 | When code in a destructor threw an exception, it went unnoticed |
1762 | in earlier versions of Perl, unless someone happened to be | |
1763 | looking in $@ just after the point the destructor happened to | |
1764 | run. Such failures are now visible as warnings when warnings are | |
1765 | enabled. | |
c7c04614 | 1766 | |
7a95317d | 1767 | =head2 Locale bugs fixed |
883d36a6 | 1768 | |
7a95317d GS |
1769 | printf() and sprintf() previously reset the numeric locale |
1770 | back to the default "C" locale. This has been fixed. | |
883d36a6 | 1771 | |
7a95317d GS |
1772 | Numbers formatted according to the local numeric locale |
1773 | (such as using a decimal comma instead of a decimal dot) caused | |
1774 | "isn't numeric" warnings, even while the operations accessing | |
1775 | those numbers produced correct results. These warnings have been | |
1776 | discontinued. | |
954c1994 | 1777 | |
7a95317d | 1778 | =head2 Memory leaks |
954c1994 | 1779 | |
7a95317d GS |
1780 | The C<eval 'return sub {...}'> construct could sometimes leak |
1781 | memory. This has been fixed. | |
f8284313 | 1782 | |
7a95317d GS |
1783 | Operations that aren't filehandle constructors used to leak memory |
1784 | when used on invalid filehandles. This has been fixed. | |
5fdc711f | 1785 | |
7a95317d GS |
1786 | Constructs that modified C<@_> could fail to deallocate values |
1787 | in C<@_> and thus leak memory. This has been corrected. | |
5fdc711f | 1788 | |
7a95317d | 1789 | =head2 Spurious subroutine stubs after failed subroutine calls |
5fdc711f | 1790 | |
7a95317d GS |
1791 | Perl could sometimes create empty subroutine stubs when a |
1792 | subroutine was not found in the package. Such cases stopped | |
1793 | later method lookups from progressing into base packages. | |
1794 | This has been corrected. | |
694468e3 | 1795 | |
7a95317d | 1796 | =head2 Taint failures under C<-U> |
694468e3 | 1797 | |
7a95317d GS |
1798 | When running in unsafe mode, taint violations could sometimes |
1799 | cause silent failures. This has been fixed. | |
1800 | ||
1801 | =head2 END blocks and the C<-c> switch | |
1802 | ||
1803 | Prior versions used to run BEGIN B<and> END blocks when Perl was | |
1804 | run in compile-only mode. Since this is typically not the expected | |
1805 | behavior, END blocks are not executed anymore when the C<-c> switch | |
db517d64 | 1806 | is used, or if compilation fails. |
14218588 | 1807 | |
7a95317d | 1808 | See L<CHECK blocks> for how to run things when the compile phase ends. |
14218588 | 1809 | |
7a95317d | 1810 | =head2 Potential to leak DATA filehandles |
393fec97 | 1811 | |
7a95317d GS |
1812 | Using the C<__DATA__> token creates an implicit filehandle to |
1813 | the file that contains the token. It is the program's | |
1814 | responsibility to close it when it is done reading from it. | |
393fec97 | 1815 | |
7a95317d GS |
1816 | This caveat is now better explained in the documentation. |
1817 | See L<perldata>. | |
e02fdbd2 | 1818 | |
73b437c8 | 1819 | =head1 New or Changed Diagnostics |
ba8251e8 | 1820 | |
a99ba403 GS |
1821 | =over 4 |
1822 | ||
56e90b21 GS |
1823 | =item "%s" variable %s masks earlier declaration in same %s |
1824 | ||
ddda08b7 | 1825 | (W misc) A "my" or "our" variable has been redeclared in the current scope or statement, |
56e90b21 GS |
1826 | effectively eliminating all access to the previous instance. This is almost |
1827 | always a typographical error. Note that the earlier variable will still exist | |
1828 | until the end of the scope or until all closure referents to it are | |
1829 | destroyed. | |
1830 | ||
33633739 GS |
1831 | =item "my sub" not yet implemented |
1832 | ||
1833 | (F) Lexically scoped subroutines are not yet implemented. Don't try that | |
1834 | yet. | |
1835 | ||
1836 | =item "our" variable %s redeclared | |
1837 | ||
ddda08b7 | 1838 | (W misc) You seem to have already declared the same global once before in the |
33633739 GS |
1839 | current lexical scope. |
1840 | ||
a99ba403 GS |
1841 | =item '!' allowed only after types %s |
1842 | ||
1843 | (F) The '!' is allowed in pack() and unpack() only after certain types. | |
1844 | See L<perlfunc/pack>. | |
1845 | ||
1846 | =item / cannot take a count | |
1847 | ||
1848 | (F) You had an unpack template indicating a counted-length string, | |
1849 | but you have also specified an explicit size for the string. | |
1850 | See L<perlfunc/pack>. | |
1851 | ||
1852 | =item / must be followed by a, A or Z | |
1853 | ||
1854 | (F) You had an unpack template indicating a counted-length string, | |
1855 | which must be followed by one of the letters a, A or Z | |
1856 | to indicate what sort of string is to be unpacked. | |
1857 | See L<perlfunc/pack>. | |
1858 | ||
1859 | =item / must be followed by a*, A* or Z* | |
1860 | ||
437784d6 | 1861 | (F) You had a pack template indicating a counted-length string, |
a99ba403 GS |
1862 | Currently the only things that can have their length counted are a*, A* or Z*. |
1863 | See L<perlfunc/pack>. | |
1864 | ||
1865 | =item / must follow a numeric type | |
1866 | ||
1867 | (F) You had an unpack template that contained a '#', | |
1868 | but this did not follow some numeric unpack specification. | |
1869 | See L<perlfunc/pack>. | |
1870 | ||
a99ba403 GS |
1871 | =item /%s/: Unrecognized escape \\%c passed through |
1872 | ||
ddda08b7 | 1873 | (W regexp) You used a backslash-character combination which is not recognized |
a99ba403 | 1874 | by Perl. This combination appears in an interpolated variable or a |
1028017a JH |
1875 | C<'>-delimited regular expression. The character was understood literally. |
1876 | ||
1877 | =item /%s/: Unrecognized escape \\%c in character class passed through | |
1878 | ||
ddda08b7 | 1879 | (W regexp) You used a backslash-character combination which is not recognized |
1028017a | 1880 | by Perl inside character classes. The character was understood literally. |
a99ba403 GS |
1881 | |
1882 | =item /%s/ should probably be written as "%s" | |
1883 | ||
ddda08b7 | 1884 | (W syntax) You have used a pattern where Perl expected to find a string, |
437784d6 | 1885 | as in the first argument to C<join>. Perl will treat the true |
a99ba403 GS |
1886 | or false result of matching the pattern against $_ as the string, |
1887 | which is probably not what you had in mind. | |
1888 | ||
1889 | =item %s() called too early to check prototype | |
1890 | ||
ddda08b7 | 1891 | (W prototype) You've called a function that has a prototype before the parser saw a |
a99ba403 GS |
1892 | definition or declaration for it, and Perl could not check that the call |
1893 | conforms to the prototype. You need to either add an early prototype | |
1894 | declaration for the subroutine in question, or move the subroutine | |
1895 | definition ahead of the call to get proper prototype checking. Alternatively, | |
1896 | if you are certain that you're calling the function correctly, you may put | |
1897 | an ampersand before the name to avoid the warning. See L<perlsub>. | |
1898 | ||
56e90b21 GS |
1899 | =item %s argument is not a HASH or ARRAY element |
1900 | ||
1901 | (F) The argument to exists() must be a hash or array element, such as: | |
1902 | ||
1903 | $foo{$bar} | |
7a95317d | 1904 | $ref->{"susie"}[12] |
56e90b21 GS |
1905 | |
1906 | =item %s argument is not a HASH or ARRAY element or slice | |
1907 | ||
1908 | (F) The argument to delete() must be either a hash or array element, such as: | |
1909 | ||
1910 | $foo{$bar} | |
7a95317d | 1911 | $ref->{"susie"}[12] |
56e90b21 GS |
1912 | |
1913 | or a hash or array slice, such as: | |
1914 | ||
1915 | @foo[$bar, $baz, $xyzzy] | |
1916 | @{$ref->[12]}{"susie", "queue"} | |
1917 | ||
afebc493 GS |
1918 | =item %s argument is not a subroutine name |
1919 | ||
1920 | (F) The argument to exists() for C<exists &sub> must be a subroutine | |
1921 | name, and not a subroutine call. C<exists &sub()> will generate this error. | |
1922 | ||
09bef843 SB |
1923 | =item %s package attribute may clash with future reserved word: %s |
1924 | ||
ddda08b7 | 1925 | (W reserved) A lowercase attribute name was used that had a package-specific handler. |
09bef843 SB |
1926 | That name might have a meaning to Perl itself some day, even though it |
1927 | doesn't yet. Perhaps you should use a mixed-case attribute name, instead. | |
1928 | See L<attributes>. | |
1929 | ||
cc507455 | 1930 | =item (in cleanup) %s |
6b121555 | 1931 | |
ddda08b7 | 1932 | (W misc) This prefix usually indicates that a DESTROY() method raised |
a99ba403 GS |
1933 | the indicated exception. Since destructors are usually called by |
1934 | the system at arbitrary points during execution, and often a vast | |
1935 | number of times, the warning is issued only once for any number | |
1936 | of failures that would otherwise result in the same message being | |
1937 | repeated. | |
1938 | ||
1939 | Failure of user callbacks dispatched using the C<G_KEEPERR> flag | |
1940 | could also result in this warning. See L<perlcall/G_KEEPERR>. | |
1941 | ||
1942 | =item <> should be quotes | |
1943 | ||
c47ff5f1 | 1944 | (F) You wrote C<< require <file> >> when you should have written |
a99ba403 GS |
1945 | C<require 'file'>. |
1946 | ||
1947 | =item Attempt to join self | |
1948 | ||
1949 | (F) You tried to join a thread from within itself, which is an | |
1950 | impossible task. You may be joining the wrong thread, or you may | |
1951 | need to move the join() to some other thread. | |
1952 | ||
1953 | =item Bad evalled substitution pattern | |
1954 | ||
1955 | (F) You've used the /e switch to evaluate the replacement for a | |
1956 | substitution, but perl found a syntax error in the code to evaluate, | |
1957 | most likely an unexpected right brace '}'. | |
1958 | ||
1959 | =item Bad realloc() ignored | |
1960 | ||
1961 | (S) An internal routine called realloc() on something that had never been | |
1962 | malloc()ed in the first place. Mandatory, but can be disabled by | |
1963 | setting environment variable C<PERL_BADFREE> to 1. | |
1964 | ||
34d09196 GS |
1965 | =item Bareword found in conditional |
1966 | ||
ddda08b7 | 1967 | (W bareword) The compiler found a bareword where it expected a conditional, |
34d09196 GS |
1968 | which often indicates that an || or && was parsed as part of the |
1969 | last argument of the previous construct, for example: | |
1970 | ||
1971 | open FOO || die; | |
1972 | ||
1973 | It may also indicate a misspelled constant that has been interpreted | |
1974 | as a bareword: | |
1975 | ||
1976 | use constant TYPO => 1; | |
1977 | if (TYOP) { print "foo" } | |
1978 | ||
1979 | The C<strict> pragma is useful in avoiding such errors. | |
1980 | ||
a99ba403 GS |
1981 | =item Binary number > 0b11111111111111111111111111111111 non-portable |
1982 | ||
ddda08b7 | 1983 | (W portable) The binary number you specified is larger than 2**32-1 |
a99ba403 GS |
1984 | (4294967295) and therefore non-portable between systems. See |
1985 | L<perlport> for more on portability concerns. | |
1986 | ||
1987 | =item Bit vector size > 32 non-portable | |
1988 | ||
ddda08b7 | 1989 | (W portable) Using bit vector sizes larger than 32 is non-portable. |
a99ba403 GS |
1990 | |
1991 | =item Buffer overflow in prime_env_iter: %s | |
1992 | ||
ddda08b7 | 1993 | (W internal) A warning peculiar to VMS. While Perl was preparing to iterate over |
a99ba403 GS |
1994 | %ENV, it encountered a logical name or symbol definition which was too long, |
1995 | so it was truncated to the string shown. | |
1996 | ||
1997 | =item Can't check filesystem of script "%s" | |
1998 | ||
1999 | (P) For some reason you can't check the filesystem of the script for nosuid. | |
2000 | ||
56e90b21 GS |
2001 | =item Can't declare class for non-scalar %s in "%s" |
2002 | ||
2003 | (S) Currently, only scalar variables can declared with a specific class | |
2004 | qualifier in a "my" or "our" declaration. The semantics may be extended | |
2005 | for other types of variables in future. | |
2006 | ||
2007 | =item Can't declare %s in "%s" | |
2008 | ||
2009 | (F) Only scalar, array, and hash variables may be declared as "my" or | |
2010 | "our" variables. They must have ordinary identifiers as names. | |
2011 | ||
0b5b802d GS |
2012 | =item Can't ignore signal CHLD, forcing to default |
2013 | ||
ddda08b7 | 2014 | (W signal) Perl has detected that it is being run with the SIGCHLD signal |
0b5b802d GS |
2015 | (sometimes known as SIGCLD) disabled. Since disabling this signal |
2016 | will interfere with proper determination of exit status of child | |
2017 | processes, Perl has reset the signal to its default value. | |
2018 | This situation typically indicates that the parent program under | |
642f9deb | 2019 | which Perl may be running (e.g., cron) is being very careless. |
0b5b802d | 2020 | |
a99ba403 GS |
2021 | =item Can't modify non-lvalue subroutine call |
2022 | ||
437784d6 GS |
2023 | (F) Subroutines meant to be used in lvalue context should be declared as |
2024 | such, see L<perlsub/"Lvalue subroutines">. | |
a99ba403 GS |
2025 | |
2026 | =item Can't read CRTL environ | |
2027 | ||
2028 | (S) A warning peculiar to VMS. Perl tried to read an element of %ENV | |
2029 | from the CRTL's internal environment array and discovered the array was | |
2030 | missing. You need to figure out where your CRTL misplaced its environ | |
2031 | or define F<PERL_ENV_TABLES> (see L<perlvms>) so that environ is not searched. | |
2032 | ||
2033 | =item Can't remove %s: %s, skipping file | |
2034 | ||
2035 | (S) You requested an inplace edit without creating a backup file. Perl | |
2036 | was unable to remove the original file to replace it with the modified | |
2037 | file. The file was left unmodified. | |
2038 | ||
2039 | =item Can't return %s from lvalue subroutine | |
2040 | ||
2041 | (F) Perl detected an attempt to return illegal lvalues (such | |
2042 | as temporary or readonly values) from a subroutine used as an lvalue. | |
2043 | This is not allowed. | |
2044 | ||
2045 | =item Can't weaken a nonreference | |
2046 | ||
2047 | (F) You attempted to weaken something that was not a reference. Only | |
2048 | references can be weakened. | |
2049 | ||
2050 | =item Character class [:%s:] unknown | |
2051 | ||
2052 | (F) The class in the character class [: :] syntax is unknown. | |
437784d6 | 2053 | See L<perlre>. |
a99ba403 GS |
2054 | |
2055 | =item Character class syntax [%s] belongs inside character classes | |
2056 | ||
ddda08b7 | 2057 | (W unsafe) The character class constructs [: :], [= =], and [. .] go |
a99ba403 | 2058 | I<inside> character classes, the [] are part of the construct, |
437784d6 GS |
2059 | for example: /[012[:alpha:]345]/. Note that [= =] and [. .] |
2060 | are not currently implemented; they are simply placeholders for | |
2061 | future extensions. | |
a99ba403 GS |
2062 | |
2063 | =item Constant is not %s reference | |
2064 | ||
2065 | (F) A constant value (perhaps declared using the C<use constant> pragma) | |
2066 | is being dereferenced, but it amounts to the wrong type of reference. The | |
2067 | message indicates the type of reference that was expected. This usually | |
2068 | indicates a syntax error in dereferencing the constant value. | |
2069 | See L<perlsub/"Constant Functions"> and L<constant>. | |
2070 | ||
a99ba403 GS |
2071 | =item constant(%s): %s |
2072 | ||
f0af216f GS |
2073 | (F) The parser found inconsistencies either while attempting to define an |
2074 | overloaded constant, or when trying to find the character name specified | |
2075 | in the C<\N{...}> escape. Perhaps you forgot to load the corresponding | |
2076 | C<overload> or C<charnames> pragma? See L<charnames> and L<overload>. | |
a99ba403 | 2077 | |
6798c92b GS |
2078 | =item CORE::%s is not a keyword |
2079 | ||
2080 | (F) The CORE:: namespace is reserved for Perl keywords. | |
2081 | ||
a99ba403 GS |
2082 | =item defined(@array) is deprecated |
2083 | ||
2084 | (D) defined() is not usually useful on arrays because it checks for an | |
2085 | undefined I<scalar> value. If you want to see if the array is empty, | |
2086 | just use C<if (@array) { # not empty }> for example. | |
2087 | ||
2088 | =item defined(%hash) is deprecated | |
2089 | ||
2090 | (D) defined() is not usually useful on hashes because it checks for an | |
2091 | undefined I<scalar> value. If you want to see if the hash is empty, | |
2092 | just use C<if (%hash) { # not empty }> for example. | |
2093 | ||
2094 | =item Did not produce a valid header | |
2095 | ||
2096 | See Server error. | |
2097 | ||
cc507455 | 2098 | =item (Did you mean "local" instead of "our"?) |
33633739 | 2099 | |
ddda08b7 | 2100 | (W misc) Remember that "our" does not localize the declared global variable. |
33633739 GS |
2101 | You have declared it again in the same lexical scope, which seems superfluous. |
2102 | ||
a99ba403 GS |
2103 | =item Document contains no data |
2104 | ||
2105 | See Server error. | |
2106 | ||
2107 | =item entering effective %s failed | |
2108 | ||
2109 | (F) While under the C<use filetest> pragma, switching the real and | |
2110 | effective uids or gids failed. | |
6b121555 | 2111 | |
73b437c8 JH |
2112 | =item false [] range "%s" in regexp |
2113 | ||
ddda08b7 | 2114 | (W regexp) A character class range must start and end at a literal character, not |
73b437c8 JH |
2115 | another character class like C<\d> or C<[:alpha:]>. The "-" in your false |
2116 | range is interpreted as a literal "-". Consider quoting the "-", "\-". | |
2117 | See L<perlre>. | |
2118 | ||
af8c498a | 2119 | =item Filehandle %s opened only for output |
6b121555 | 2120 | |
ddda08b7 | 2121 | (W io) You tried to read from a filehandle opened only for writing. If you |
437784d6 | 2122 | intended it to be a read/write filehandle, you needed to open it with |
c47ff5f1 GS |
2123 | "+<" or "+>" or "+>>" instead of with "<" or nothing. If |
2124 | you intended only to read from the file, use "<". See | |
af8c498a | 2125 | L<perlfunc/open>. |
e02fdbd2 | 2126 | |
56e90b21 GS |
2127 | =item flock() on closed filehandle %s |
2128 | ||
ddda08b7 | 2129 | (W closed) The filehandle you're attempting to flock() got itself closed some |
56e90b21 GS |
2130 | time before now. Check your logic flow. flock() operates on filehandles. |
2131 | Are you attempting to call flock() on a dirhandle by the same name? | |
2132 | ||
2133 | =item Global symbol "%s" requires explicit package name | |
2134 | ||
2135 | (F) You've said "use strict vars", which indicates that all variables | |
2136 | must either be lexically scoped (using "my"), declared beforehand using | |
2137 | "our", or explicitly qualified to say which package the global variable | |
2138 | is in (using "::"). | |
2139 | ||
a99ba403 GS |
2140 | =item Hexadecimal number > 0xffffffff non-portable |
2141 | ||
ddda08b7 | 2142 | (W portable) The hexadecimal number you specified is larger than 2**32-1 |
a99ba403 GS |
2143 | (4294967295) and therefore non-portable between systems. See |
2144 | L<perlport> for more on portability concerns. | |
2145 | ||
2146 | =item Ill-formed CRTL environ value "%s" | |
2147 | ||
ddda08b7 | 2148 | (W internal) A warning peculiar to VMS. Perl tried to read the CRTL's internal |
a99ba403 | 2149 | environ array, and encountered an element without the C<=> delimiter |
4375e838 | 2150 | used to separate keys from values. The element is ignored. |
a99ba403 GS |
2151 | |
2152 | =item Ill-formed message in prime_env_iter: |%s| | |
2153 | ||
ddda08b7 | 2154 | (W internal) A warning peculiar to VMS. Perl tried to read a logical name |
a99ba403 GS |
2155 | or CLI symbol definition when preparing to iterate over %ENV, and |
2156 | didn't see the expected delimiter between key and value, so the | |
2157 | line was ignored. | |
2158 | ||
2159 | =item Illegal binary digit %s | |
2160 | ||
437784d6 | 2161 | (F) You used a digit other than 0 or 1 in a binary number. |
a99ba403 GS |
2162 | |
2163 | =item Illegal binary digit %s ignored | |
2164 | ||
ddda08b7 | 2165 | (W digit) You may have tried to use a digit other than 0 or 1 in a binary number. |
a99ba403 GS |
2166 | Interpretation of the binary number stopped before the offending digit. |
2167 | ||
2168 | =item Illegal number of bits in vec | |
2169 | ||
2170 | (F) The number of bits in vec() (the third argument) must be a power of | |
2171 | two from 1 to 32 (or 64, if your platform supports that). | |
2172 | ||
2173 | =item Integer overflow in %s number | |
2174 | ||
ddda08b7 | 2175 | (W overflow) The hexadecimal, octal or binary number you have specified either |
c6edd1b7 | 2176 | as a literal or as an argument to hex() or oct() is too big for your |
a99ba403 GS |
2177 | architecture, and has been converted to a floating point number. On a |
2178 | 32-bit architecture the largest hexadecimal, octal or binary number | |
2179 | representable without overflow is 0xFFFFFFFF, 037777777777, or | |
2180 | 0b11111111111111111111111111111111 respectively. Note that Perl | |
2181 | transparently promotes all numbers to a floating point representation | |
2182 | internally--subject to loss of precision errors in subsequent | |
2183 | operations. | |
2184 | ||
09bef843 SB |
2185 | =item Invalid %s attribute: %s |
2186 | ||
2187 | The indicated attribute for a subroutine or variable was not recognized | |
2188 | by Perl or by a user-supplied handler. See L<attributes>. | |
2189 | ||
2190 | =item Invalid %s attributes: %s | |
2191 | ||
2192 | The indicated attributes for a subroutine or variable were not recognized | |
2193 | by Perl or by a user-supplied handler. See L<attributes>. | |
2194 | ||
73b437c8 JH |
2195 | =item invalid [] range "%s" in regexp |
2196 | ||
2197 | The offending range is now explicitly displayed. | |
2198 | ||
09bef843 SB |
2199 | =item Invalid separator character %s in attribute list |
2200 | ||
0120eecf | 2201 | (F) Something other than a colon or whitespace was seen between the |
09bef843 SB |
2202 | elements of an attribute list. If the previous attribute |
2203 | had a parenthesised parameter list, perhaps that list was terminated | |
2204 | too soon. See L<attributes>. | |
2205 | ||
a99ba403 GS |
2206 | =item Invalid separator character %s in subroutine attribute list |
2207 | ||
0120eecf | 2208 | (F) Something other than a colon or whitespace was seen between the |
a99ba403 GS |
2209 | elements of a subroutine attribute list. If the previous attribute |
2210 | had a parenthesised parameter list, perhaps that list was terminated | |
2211 | too soon. | |
2212 | ||
2213 | =item leaving effective %s failed | |
2214 | ||
2215 | (F) While under the C<use filetest> pragma, switching the real and | |
2216 | effective uids or gids failed. | |
2217 | ||
2218 | =item Lvalue subs returning %s not implemented yet | |
2219 | ||
2220 | (F) Due to limitations in the current implementation, array and hash | |
2221 | values cannot be returned in subroutines used in lvalue context. | |
2222 | See L<perlsub/"Lvalue subroutines">. | |
2223 | ||
2224 | =item Method %s not permitted | |
2225 | ||
2226 | See Server error. | |
2227 | ||
2228 | =item Missing %sbrace%s on \N{} | |
2229 | ||
2230 | (F) Wrong syntax of character name literal C<\N{charname}> within | |
2231 | double-quotish context. | |
2232 | ||
06eaf0bc GS |
2233 | =item Missing command in piped open |
2234 | ||
ddda08b7 | 2235 | (W pipe) You used the C<open(FH, "| command")> or C<open(FH, "command |")> |
06eaf0bc GS |
2236 | construction, but the command was missing or blank. |
2237 | ||
09bef843 SB |
2238 | =item Missing name in "my sub" |
2239 | ||
2240 | (F) The reserved syntax for lexically scoped subroutines requires that they | |
2241 | have a name with which they can be found. | |
2242 | ||
56e90b21 GS |
2243 | =item No %s specified for -%c |
2244 | ||
2245 | (F) The indicated command line switch needs a mandatory argument, but | |
2246 | you haven't specified one. | |
2247 | ||
2248 | =item No package name allowed for variable %s in "our" | |
2249 | ||
2250 | (F) Fully qualified variable names are not allowed in "our" declarations, | |
2251 | because that doesn't make much sense under existing semantics. Such | |
2252 | syntax is reserved for future extensions. | |
2253 | ||
2254 | =item No space allowed after -%c | |
2255 | ||
2256 | (F) The argument to the indicated command line switch must follow immediately | |
2257 | after the switch, without intervening spaces. | |
2258 | ||
a99ba403 GS |
2259 | =item no UTC offset information; assuming local time is UTC |
2260 | ||
2261 | (S) A warning peculiar to VMS. Perl was unable to find the local | |
2262 | timezone offset, so it's assuming that local system time is equivalent | |
2263 | to UTC. If it's not, define the logical name F<SYS$TIMEZONE_DIFFERENTIAL> | |
2264 | to translate to the number of seconds which need to be added to UTC to | |
2265 | get local time. | |
2266 | ||
2267 | =item Octal number > 037777777777 non-portable | |
2268 | ||
ddda08b7 | 2269 | (W portable) The octal number you specified is larger than 2**32-1 (4294967295) |
a99ba403 GS |
2270 | and therefore non-portable between systems. See L<perlport> for more |
2271 | on portability concerns. | |
2272 | ||
2273 | See also L<perlport> for writing portable code. | |
2274 | ||
2275 | =item panic: del_backref | |
2276 | ||
2277 | (P) Failed an internal consistency check while trying to reset a weak | |
2278 | reference. | |
2279 | ||
2280 | =item panic: kid popen errno read | |
2281 | ||
2282 | (F) forked child returned an incomprehensible message about its errno. | |
2283 | ||
2284 | =item panic: magic_killbackrefs | |
2285 | ||
2286 | (P) Failed an internal consistency check while trying to reset all weak | |
2287 | references to an object. | |
2288 | ||
56e90b21 GS |
2289 | =item Parentheses missing around "%s" list |
2290 | ||
ddda08b7 | 2291 | (W parenthesis) You said something like |
56e90b21 GS |
2292 | |
2293 | my $foo, $bar = @_; | |
2294 | ||
2295 | when you meant | |
2296 | ||
2297 | my ($foo, $bar) = @_; | |
2298 | ||
54884818 | 2299 | Remember that "my", "our", and "local" bind tighter than comma. |
56e90b21 | 2300 | |
a99ba403 GS |
2301 | =item Possible Y2K bug: %s |
2302 | ||
ddda08b7 | 2303 | (W y2k) You are concatenating the number 19 with another number, which |
a99ba403 GS |
2304 | could be a potential Year 2000 problem. |
2305 | ||
8cd79558 GS |
2306 | =item pragma "attrs" is deprecated, use "sub NAME : ATTRS" instead |
2307 | ||
4375e838 | 2308 | (W deprecated) You have written something like this: |
8cd79558 GS |
2309 | |
2310 | sub doit | |
2311 | { | |
2312 | use attrs qw(locked); | |
2313 | } | |
2314 | ||
2315 | You should use the new declaration syntax instead. | |
2316 | ||
2317 | sub doit : locked | |
2318 | { | |
2319 | ... | |
2320 | ||
2321 | The C<use attrs> pragma is now obsolete, and is only provided for | |
2322 | backward-compatibility. See L<perlsub/"Subroutine Attributes">. | |
2323 | ||
2324 | ||
a99ba403 GS |
2325 | =item Premature end of script headers |
2326 | ||
2327 | See Server error. | |
2328 | ||
0b5b802d GS |
2329 | =item Repeat count in pack overflows |
2330 | ||
2331 | (F) You can't specify a repeat count so large that it overflows | |
2332 | your signed integers. See L<perlfunc/pack>. | |
2333 | ||
2334 | =item Repeat count in unpack overflows | |
2335 | ||
2336 | (F) You can't specify a repeat count so large that it overflows | |
2337 | your signed integers. See L<perlfunc/unpack>. | |
2338 | ||
a99ba403 GS |
2339 | =item realloc() of freed memory ignored |
2340 | ||
2341 | (S) An internal routine called realloc() on something that had already | |
2342 | been freed. | |
2343 | ||
2344 | =item Reference is already weak | |
2345 | ||
7a95317d GS |
2346 | (W misc) You have attempted to weaken a reference that is already weak. |
2347 | Doing so has no effect. | |
2348 | ||
2349 | =item setpgrp can't take arguments | |
2350 | ||
2351 | (F) Your system has the setpgrp() from BSD 4.2, which takes no arguments, | |
2352 | unlike POSIX setpgid(), which takes a process ID and process group ID. | |
2353 | ||
2354 | =item Strange *+?{} on zero-length expression | |
2355 | ||
2356 | (W regexp) You applied a regular expression quantifier in a place where it | |
2357 | makes no sense, such as on a zero-width assertion. | |
2358 | Try putting the quantifier inside the assertion instead. For example, | |
2359 | the way to match "abc" provided that it is followed by three | |
2360 | repetitions of "xyz" is C</abc(?=(?:xyz){3})/>, not C</abc(?=xyz){3}/>. | |
2361 | ||
2362 | =item switching effective %s is not implemented | |
2363 | ||
2364 | (F) While under the C<use filetest> pragma, we cannot switch the | |
2365 | real and effective uids or gids. | |
2366 | ||
2367 | =item This Perl can't reset CRTL environ elements (%s) | |
2368 | ||
2369 | =item This Perl can't set CRTL environ elements (%s=%s) | |
2370 | ||
2371 | (W internal) Warnings peculiar to VMS. You tried to change or delete an element | |
2372 | of the CRTL's internal environ array, but your copy of Perl wasn't | |
2373 | built with a CRTL that contained the setenv() function. You'll need to | |
2374 | rebuild Perl with a CRTL that does, or redefine F<PERL_ENV_TABLES> (see | |
2375 | L<perlvms>) so that the environ array isn't the target of the change to | |
2376 | %ENV which produced the warning. | |
2377 | ||
2378 | =item Too late to run %s block | |
2379 | ||
2380 | (W void) A CHECK or INIT block is being defined during run time proper, | |
2381 | when the opportunity to run them has already passed. Perhaps you are | |
2382 | loading a file with C<require> or C<do> when you should be using | |
2383 | C<use> instead. Or perhaps you should put the C<require> or C<do> | |
2384 | inside a BEGIN block. | |
2385 | ||
2386 | =item Unknown open() mode '%s' | |
2387 | ||
2388 | (F) The second argument of 3-argument open() is not among the list | |
2389 | of valid modes: C<< < >>, C<< > >>, C<<< >> >>>, C<< +< >>, | |
2390 | C<< +> >>, C<<< +>> >>>, C<-|>, C<|->. | |
2391 | ||
2392 | =item Unknown process %x sent message to prime_env_iter: %s | |
2393 | ||
2394 | (P) An error peculiar to VMS. Perl was reading values for %ENV before | |
2395 | iterating over it, and someone else stuck a message in the stream of | |
2396 | data Perl expected. Someone's very confused, or perhaps trying to | |
2397 | subvert Perl's population of %ENV for nefarious purposes. | |
2398 | ||
2399 | =item Unrecognized escape \\%c passed through | |
2400 | ||
2401 | (W misc) You used a backslash-character combination which is not recognized | |
2402 | by Perl. The character was understood literally. | |
2403 | ||
2404 | =item Unterminated attribute parameter in attribute list | |
2405 | ||
2406 | (F) The lexer saw an opening (left) parenthesis character while parsing an | |
2407 | attribute list, but the matching closing (right) parenthesis | |
2408 | character was not found. You may need to add (or remove) a backslash | |
2409 | character to get your parentheses to balance. See L<attributes>. | |
2410 | ||
2411 | =item Unterminated attribute list | |
2412 | ||
2413 | (F) The lexer found something other than a simple identifier at the start | |
2414 | of an attribute, and it wasn't a semicolon or the start of a | |
2415 | block. Perhaps you terminated the parameter list of the previous attribute | |
2416 | too soon. See L<attributes>. | |
2417 | ||
2418 | =item Unterminated attribute parameter in subroutine attribute list | |
2419 | ||
2420 | (F) The lexer saw an opening (left) parenthesis character while parsing a | |
2421 | subroutine attribute list, but the matching closing (right) parenthesis | |
2422 | character was not found. You may need to add (or remove) a backslash | |
2423 | character to get your parentheses to balance. | |
2424 | ||
2425 | =item Unterminated subroutine attribute list | |
2426 | ||
2427 | (F) The lexer found something other than a simple identifier at the start | |
2428 | of a subroutine attribute, and it wasn't a semicolon or the start of a | |
2429 | block. Perhaps you terminated the parameter list of the previous attribute | |
2430 | too soon. | |
2431 | ||
2432 | =item Value of CLI symbol "%s" too long | |
2433 | ||
2434 | (W misc) A warning peculiar to VMS. Perl tried to read the value of an %ENV | |
2435 | element from a CLI symbol table, and found a resultant string longer | |
2436 | than 1024 characters. The return value has been truncated to 1024 | |
2437 | characters. | |
2438 | ||
2439 | =item Version number must be a constant number | |
2440 | ||
2441 | (P) The attempt to translate a C<use Module n.n LIST> statement into | |
2442 | its equivalent C<BEGIN> block found an internal inconsistency with | |
2443 | the version number. | |
2444 | ||
2445 | =back | |
2446 | ||
2447 | =head1 New tests | |
2448 | ||
2449 | =over 4 | |
2450 | ||
2451 | =item lib/attrs | |
2452 | ||
2453 | Compatibility tests for C<sub : attrs> vs the older C<use attrs>. | |
2454 | ||
2455 | =item lib/env | |
2456 | ||
2457 | Tests for new environment scalar capability (e.g., C<use Env qw($BAR);>). | |
2458 | ||
2459 | =item lib/env-array | |
2460 | ||
2461 | Tests for new environment array capability (e.g., C<use Env qw(@PATH);>). | |
2462 | ||
2463 | =item lib/io_const | |
2464 | ||
2465 | IO constants (SEEK_*, _IO*). | |
2466 | ||
2467 | =item lib/io_dir | |
2468 | ||
2469 | Directory-related IO methods (new, read, close, rewind, tied delete). | |
2470 | ||
2471 | =item lib/io_multihomed | |
2472 | ||
2473 | INET sockets with multi-homed hosts. | |
2474 | ||
2475 | =item lib/io_poll | |
2476 | ||
2477 | IO poll(). | |
2478 | ||
2479 | =item lib/io_unix | |
2480 | ||
2481 | UNIX sockets. | |
2482 | ||
2483 | =item op/attrs | |
2484 | ||
2485 | Regression tests for C<my ($x,@y,%z) : attrs> and <sub : attrs>. | |
2486 | ||
2487 | =item op/filetest | |
2488 | ||
2489 | File test operators. | |
2490 | ||
2491 | =item op/lex_assign | |
2492 | ||
2493 | Verify operations that access pad objects (lexicals and temporaries). | |
2494 | ||
2495 | =item op/exists_sub | |
2496 | ||
2497 | Verify C<exists &sub> operations. | |
2498 | ||
2499 | =back | |
2500 | ||
2501 | =head1 Incompatible Changes | |
2502 | ||
2503 | =head2 Perl Source Incompatibilities | |
2504 | ||
2505 | Beware that any new warnings that have been added or old ones | |
2506 | that have been enhanced are B<not> considered incompatible changes. | |
2507 | ||
2508 | Since all new warnings must be explicitly requested via the C<-w> | |
2509 | switch or the C<warnings> pragma, it is ultimately the programmer's | |
2510 | responsibility to ensure that warnings are enabled judiciously. | |
2511 | ||
2512 | =over 4 | |
2513 | ||
2514 | =item CHECK is a new keyword | |
2515 | ||
2516 | All subroutine definitions named CHECK are now special. See | |
2517 | C</"Support for CHECK blocks"> for more information. | |
2518 | ||
2519 | =item Treatment of list slices of undef has changed | |
2520 | ||
2521 | There is a potential incompatibility in the behavior of list slices | |
2522 | that are comprised entirely of undefined values. | |
2523 | See L</"Behavior of list slices is more consistent">. | |
2524 | ||
2525 | =head2 Format of $English::PERL_VERSION is different | |
2526 | ||
2527 | The English module now sets $PERL_VERSION to $^V (a string value) rather | |
2528 | than C<$]> (a numeric value). This is a potential incompatibility. | |
2529 | Send us a report via perlbug if you are affected by this. | |
2530 | ||
2531 | See L</"Improved Perl version numbering system"> for the reasons for | |
2532 | this change. | |
2533 | ||
2534 | =item Literals of the form C<1.2.3> parse differently | |
2535 | ||
2536 | Previously, numeric literals with more than one dot in them were | |
2537 | interpreted as a floating point number concatenated with one or more | |
2538 | numbers. Such "numbers" are now parsed as strings composed of the | |
2539 | specified ordinals. | |
2540 | ||
2541 | For example, C<print 97.98.99> used to output C<97.9899> in earlier | |
2542 | versions, but now prints C<abc>. | |
2543 | ||
2544 | See L</"Support for strings represented as a vector of ordinals">. | |
2545 | ||
2546 | =item Possibly changed pseudo-random number generator | |
2547 | ||
2548 | Perl programs that depend on reproducing a specific set of pseudo-random | |
2549 | numbers may now produce different output due to improvements made to the | |
2550 | rand() builtin. You can use C<sh Configure -Drandfunc=rand> to obtain | |
2551 | the old behavior. | |
2552 | ||
2553 | See L</"Better pseudo-random number generator">. | |
2554 | ||
2555 | =item Hashing function for hash keys has changed | |
2556 | ||
2557 | Even though Perl hashes are not order preserving, the apparently | |
2558 | random order encountered when iterating on the contents of a hash | |
2559 | is actually determined by the hashing algorithm used. Improvements | |
2560 | in the algorithm may yield a random order that is B<different> from | |
2561 | that of previous versions, especially when iterating on hashes. | |
2562 | ||
2563 | See L</"Better worst-case behavior of hashes"> for additional | |
2564 | information. | |
2565 | ||
2566 | =item C<undef> fails on read only values | |
2567 | ||
2568 | Using the C<undef> operator on a readonly value (such as $1) has | |
2569 | the same effect as assigning C<undef> to the readonly value--it | |
2570 | throws an exception. | |
2571 | ||
2572 | =item Close-on-exec bit may be set on pipe and socket handles | |
2573 | ||
2574 | Pipe and socket handles are also now subject to the close-on-exec | |
2575 | behavior determined by the special variable $^F. | |
2576 | ||
2577 | See L</"More consistent close-on-exec behavior">. | |
2578 | ||
2579 | =item Writing C<"$$1"> to mean C<"${$}1"> is unsupported | |
2580 | ||
2581 | Perl 5.004 deprecated the interpretation of C<$$1> and | |
2582 | similar within interpolated strings to mean C<$$ . "1">, | |
2583 | but still allowed it. | |
2584 | ||
2585 | In Perl 5.6.0 and later, C<"$$1"> always means C<"${$1}">. | |
2586 | ||
2587 | =item delete(), values() and C<\(%h)> operate on aliases to values, not copies | |
2588 | ||
2589 | delete(), each(), values() and hashes in a list context return the actual | |
2590 | values in the hash, instead of copies (as they used to in earlier | |
2591 | versions). Typical idioms for using these constructs copy the | |
2592 | returned values, but this can make a significant difference when | |
2593 | creating references to the returned values. Keys in the hash are still | |
2594 | returned as copies when iterating on a hash. | |
2595 | ||
2596 | See also L</"delete(), each(), values() and hash iteration are faster">. | |
2597 | ||
2598 | =item vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS | |
2599 | ||
2600 | vec() generates a run-time error if the BITS argument is not | |
2601 | a valid power-of-two integer. | |
2602 | ||
2603 | =item Text of some diagnostic output has changed | |
2604 | ||
2605 | Most references to internal Perl operations in diagnostics | |
2606 | have been changed to be more descriptive. This may be an | |
2607 | issue for programs that may incorrectly rely on the exact | |
2608 | text of diagnostics for proper functioning. | |
2609 | ||
2610 | =item C<%@> has been removed | |
2611 | ||
2612 | The undocumented special variable C<%@> that used to accumulate | |
2613 | "background" errors (such as those that happen in DESTROY()) | |
2614 | has been removed, because it could potentially result in memory | |
2615 | leaks. | |
2616 | ||
2617 | =item Parenthesized not() behaves like a list operator | |
a99ba403 | 2618 | |
7a95317d GS |
2619 | The C<not> operator now falls under the "if it looks like a function, |
2620 | it behaves like a function" rule. | |
a99ba403 | 2621 | |
7a95317d GS |
2622 | As a result, the parenthesized form can be used with C<grep> and C<map>. |
2623 | The following construct used to be a syntax error before, but it works | |
2624 | as expected now: | |
a99ba403 | 2625 | |
7a95317d | 2626 | grep not($_), @things; |
a99ba403 | 2627 | |
7a95317d GS |
2628 | On the other hand, using C<not> with a literal list slice may not |
2629 | work. The following previously allowed construct: | |
a99ba403 | 2630 | |
7a95317d | 2631 | print not (1,2,3)[0]; |
a99ba403 | 2632 | |
7a95317d | 2633 | needs to be written with additional parentheses now: |
a99ba403 | 2634 | |
7a95317d | 2635 | print not((1,2,3)[0]); |
a99ba403 | 2636 | |
7a95317d | 2637 | The behavior remains unaffected when C<not> is not followed by parentheses. |
a99ba403 | 2638 | |
7a95317d | 2639 | =item Semantics of bareword prototype C<(*)> have changed |
a99ba403 | 2640 | |
7a95317d GS |
2641 | The semantics of the bareword prototype C<*> have changed. Perl 5.005 |
2642 | always coerced simple scalar arguments to a typeglob, which wasn't useful | |
2643 | in situations where the subroutine must distinguish between a simple | |
2644 | scalar and a typeglob. The new behavior is to not coerce bareword | |
2645 | arguments to a typeglob. The value will always be visible as either | |
2646 | a simple scalar or as a reference to a typeglob. | |
ddda08b7 | 2647 | |
7a95317d | 2648 | See L</"More functional bareword prototype (*)">. |
ddda08b7 | 2649 | |
7a95317d | 2650 | =head2 Semantics of bit operators may have changed on 64-bit platforms |
a99ba403 | 2651 | |
7a95317d GS |
2652 | If your platform is either natively 64-bit or if Perl has been |
2653 | configured to used 64-bit integers, i.e., $Config{ivsize} is 8, | |
2654 | there may be a potential incompatibility in the behavior of bitwise | |
2655 | numeric operators (& | ^ ~ << >>). These operators used to strictly | |
2656 | operate on the lower 32 bits of integers in previous versions, but now | |
2657 | operate over the entire native integral width. In particular, note | |
2658 | that unary C<~> will produce different results on platforms that have | |
2659 | different $Config{ivsize}. For portability, be sure to mask off | |
2660 | the excess bits in the result of unary C<~>, e.g., C<~$x & 0xffffffff>. | |
a99ba403 | 2661 | |
7a95317d | 2662 | See L</"Bit operators support full native integer width">. |
a99ba403 | 2663 | |
7a95317d | 2664 | =head2 More builtins taint their results |
a99ba403 | 2665 | |
7a95317d GS |
2666 | As described in L</"Improved security features">, there may be more |
2667 | sources of taint in a Perl program. | |
af8c498a | 2668 | |
7a95317d GS |
2669 | To avoid these new tainting behaviors, you can build Perl with the |
2670 | Configure option C<-Accflags=-DINCOMPLETE_TAINTS>. Beware that the | |
2671 | ensuing perl binary may be insecure. | |
af8c498a | 2672 | |
7a95317d | 2673 | =back |
09bef843 | 2674 | |
7a95317d | 2675 | =head2 C Source Incompatibilities |
09bef843 | 2676 | |
7a95317d | 2677 | =over 4 |
09bef843 | 2678 | |
7a95317d | 2679 | =item C<PERL_POLLUTE> |
09bef843 | 2680 | |
7a95317d GS |
2681 | Release 5.005 grandfathered old global symbol names by providing preprocessor |
2682 | macros for extension source compatibility. As of release 5.6.0, these | |
2683 | preprocessor definitions are not available by default. You need to explicitly | |
2684 | compile perl with C<-DPERL_POLLUTE> to get these definitions. For | |
2685 | extensions still using the old symbols, this option can be | |
2686 | specified via MakeMaker: | |
09bef843 | 2687 | |
7a95317d | 2688 | perl Makefile.PL POLLUTE=1 |
09bef843 | 2689 | |
7a95317d | 2690 | =item C<PERL_IMPLICIT_CONTEXT> |
09bef843 | 2691 | |
7a95317d GS |
2692 | This new build option provides a set of macros for all API functions |
2693 | such that an implicit interpreter/thread context argument is passed to | |
2694 | every API function. As a result of this, something like C<sv_setsv(foo,bar)> | |
2695 | amounts to a macro invocation that actually translates to something like | |
2696 | C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected | |
2697 | to not have any significant source compatibility issues, the difference | |
2698 | between a macro and a real function call will need to be considered. | |
09bef843 | 2699 | |
7a95317d GS |
2700 | This means that there B<is> a source compatibility issue as a result of |
2701 | this if your extensions attempt to use pointers to any of the Perl API | |
2702 | functions. | |
eb6e2d6f | 2703 | |
7a95317d GS |
2704 | Note that the above issue is not relevant to the default build of |
2705 | Perl, whose interfaces continue to match those of prior versions | |
2706 | (but subject to the other options described here). | |
eb6e2d6f | 2707 | |
7a95317d GS |
2708 | See L<perlguts/"The Perl API"> for detailed information on the |
2709 | ramifications of building Perl with this option. | |
ba8251e8 | 2710 | |
7a95317d GS |
2711 | NOTE: PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built |
2712 | with one of -Dusethreads, -Dusemultiplicity, or both. It is not | |
2713 | intended to be enabled by users at this time. | |
a99ba403 | 2714 | |
7a95317d | 2715 | =item C<PERL_POLLUTE_MALLOC> |
27806c82 | 2716 | |
7a95317d GS |
2717 | Enabling Perl's malloc in release 5.005 and earlier caused the namespace of |
2718 | the system's malloc family of functions to be usurped by the Perl versions, | |
2719 | since by default they used the same names. Besides causing problems on | |
2720 | platforms that do not allow these functions to be cleanly replaced, this | |
2721 | also meant that the system versions could not be called in programs that | |
2722 | used Perl's malloc. Previous versions of Perl have allowed this behaviour | |
2723 | to be suppressed with the HIDEMYMALLOC and EMBEDMYMALLOC preprocessor | |
2724 | definitions. | |
3175b8cd | 2725 | |
7a95317d GS |
2726 | As of release 5.6.0, Perl's malloc family of functions have default names |
2727 | distinct from the system versions. You need to explicitly compile perl with | |
2728 | C<-DPERL_POLLUTE_MALLOC> to get the older behaviour. HIDEMYMALLOC | |
2729 | and EMBEDMYMALLOC have no effect, since the behaviour they enabled is now | |
2730 | the default. | |
a99ba403 | 2731 | |
7a95317d GS |
2732 | Note that these functions do B<not> constitute Perl's memory allocation API. |
2733 | See L<perlguts/"Memory Allocation"> for further information about that. | |
a99ba403 | 2734 | |
7a95317d | 2735 | =back |
a99ba403 | 2736 | |
7a95317d | 2737 | =head2 Compatible C Source API Changes |
a99ba403 | 2738 | |
7a95317d | 2739 | =over |
a99ba403 | 2740 | |
7a95317d | 2741 | =item C<PATCHLEVEL> is now C<PERL_VERSION> |
34d09196 | 2742 | |
7a95317d GS |
2743 | The cpp macros C<PERL_REVISION>, C<PERL_VERSION>, and C<PERL_SUBVERSION> |
2744 | are now available by default from perl.h, and reflect the base revision, | |
2745 | patchlevel, and subversion respectively. C<PERL_REVISION> had no | |
2746 | prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were | |
2747 | previously available as C<PATCHLEVEL> and C<SUBVERSION>. | |
34d09196 | 2748 | |
7a95317d GS |
2749 | The new names cause less pollution of the B<cpp> namespace and reflect what |
2750 | the numbers have come to stand for in common practice. For compatibility, | |
2751 | the old names are still supported when F<patchlevel.h> is explicitly | |
2752 | included (as required before), so there is no source incompatibility | |
2753 | from the change. | |
34d09196 | 2754 | |
7a95317d | 2755 | =back |
a99ba403 | 2756 | |
7a95317d | 2757 | =head2 Binary Incompatibilities |
a99ba403 | 2758 | |
7a95317d GS |
2759 | In general, the default build of this release is expected to be binary |
2760 | compatible for extensions built with the 5.005 release or its maintenance | |
2761 | versions. However, specific platforms may have broken binary compatibility | |
2762 | due to changes in the defaults used in hints files. Therefore, please be | |
2763 | sure to always check the platform-specific README files for any notes to | |
2764 | the contrary. | |
a99ba403 | 2765 | |
7a95317d GS |
2766 | The usethreads or usemultiplicity builds are B<not> binary compatible |
2767 | with the corresponding builds in 5.005. | |
a99ba403 | 2768 | |
7a95317d GS |
2769 | On platforms that require an explicit list of exports (AIX, OS/2 and Windows, |
2770 | among others), purely internal symbols such as parser functions and the | |
2771 | run time opcodes are not exported by default. Perl 5.005 used to export | |
2772 | all functions irrespective of whether they were considered part of the | |
2773 | public API or not. | |
a99ba403 | 2774 | |
7a95317d | 2775 | For the full list of public API functions, see L<perlapi>. |
3175b8cd | 2776 | |
fc641c2d JH |
2777 | =head1 Known Problems |
2778 | ||
227e8dd4 | 2779 | =head2 Thread test failures |
fc641c2d | 2780 | |
97017a80 | 2781 | The subtests 19 and 20 of lib/thr5005.t test are known to fail due to |
227e8dd4 GS |
2782 | fundamental problems in the 5.005 threading implementation. These are |
2783 | not new failures--Perl 5.005_0x has the same bugs, but didn't have these | |
2784 | tests. | |
fc641c2d JH |
2785 | |
2786 | =head2 EBCDIC platforms not supported | |
2787 | ||
227e8dd4 GS |
2788 | In earlier releases of Perl, EBCDIC environments like OS390 (also |
2789 | known as Open Edition MVS) and VM-ESA were supported. Due to changes | |
2790 | required by the UTF-8 (Unicode) support, the EBCDIC platforms are not | |
2791 | supported in Perl 5.6.0. | |
fc641c2d | 2792 | |
d57b1ce7 GS |
2793 | =head2 In 64-bit HP-UX the lib/io_multihomed test may hang |
2794 | ||
2795 | The lib/io_multihomed test may hang in HP-UX if Perl has been | |
2796 | configured to be 64-bit. Because other 64-bit platforms do not | |
2797 | hang in this test, HP-UX is suspect. All other tests pass | |
2798 | in 64-bit HP-UX. The test attempts to create and connect to | |
2799 | "multihomed" sockets (sockets which have multiple IP addresses). | |
2800 | ||
f46deeb4 JH |
2801 | =head2 NEXTSTEP 3.3 POSIX test failure |
2802 | ||
2803 | In NEXTSTEP 3.3p2 the implementation of the strftime(3) in the | |
2804 | operating system libraries is buggy: the %j format numbers the days of | |
2805 | a month starting from zero, which, while being logical to programmers, | |
2806 | will cause the subtests 19 to 27 of the lib/posix test may fail. | |
2807 | ||
2cae8c0d JH |
2808 | =head2 Tru64 (aka Digital UNIX, aka DEC OSF/1) lib/sdbm test failure with gcc |
2809 | ||
2810 | If compiled with gcc 2.95 the lib/sdbm test will fail (dump core). | |
2811 | The cure is to use the vendor cc, it comes with the operating system | |
2812 | and produces good code. | |
2813 | ||
fc641c2d JH |
2814 | =head2 UNICOS/mk CC failures during Configure run |
2815 | ||
2816 | In UNICOS/mk the following errors may appear during the Configure run: | |
2817 | ||
2818 | Guessing which symbols your C compiler and preprocessor define... | |
2819 | CC-20 cc: ERROR File = try.c, Line = 3 | |
2820 | ... | |
2821 | bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K | |
2822 | ... | |
2823 | 4 errors detected in the compilation of "try.c". | |
2824 | ||
2825 | The culprit is the broken awk of UNICOS/mk. The effect is fortunately | |
2826 | rather mild: Perl itself is not adversely affected by the error, only | |
2827 | the h2ph utility coming with Perl, and that is rather rarely needed | |
2828 | these days. | |
2829 | ||
14190b26 GS |
2830 | =head2 Arrow operator and arrays |
2831 | ||
2832 | When the left argument to the arrow operator C<< -> >> is an array, or | |
2833 | the C<scalar> operator operating on an array, the result of the | |
2834 | operation must be considered erroneous. For example: | |
2835 | ||
2836 | @x->[2] | |
2837 | scalar(@x)->[2] | |
2838 | ||
2839 | These expressions will get run-time errors in some future release of | |
2840 | Perl. | |
2841 | ||
4bca7e4f | 2842 | =head2 Experimental features |
fc641c2d | 2843 | |
227e8dd4 GS |
2844 | As discussed above, many features are still experimental. Interfaces and |
2845 | implementation of these features are subject to change, and in extreme cases, | |
2846 | even subject to removal in some future release of Perl. These features | |
2847 | include the following: | |
fc641c2d JH |
2848 | |
2849 | =over 4 | |
2850 | ||
2851 | =item Threads | |
2852 | ||
2853 | =item Unicode | |
2854 | ||
4bca7e4f GS |
2855 | =item 64-bit support |
2856 | ||
fc641c2d JH |
2857 | =item Lvalue subroutines |
2858 | ||
2859 | =item Weak references | |
2860 | ||
4bca7e4f | 2861 | =item The pseudo-hash data type |
fc641c2d JH |
2862 | |
2863 | =item The Compiler suite | |
2864 | ||
4bca7e4f GS |
2865 | =item Internal implementation of file globbing |
2866 | ||
227e8dd4 | 2867 | =item The DB module |
fc641c2d | 2868 | |
227e8dd4 | 2869 | =item The regular expression constructs C<(?{ code })> and C<(??{ code })> |
fc641c2d JH |
2870 | |
2871 | =back | |
2872 | ||
7a95317d GS |
2873 | =head1 Obsolete Diagnostics |
2874 | ||
2875 | =over 4 | |
2876 | ||
2877 | =item Character class syntax [: :] is reserved for future extensions | |
2878 | ||
2879 | (W) Within regular expression character classes ([]) the syntax beginning | |
2880 | with "[:" and ending with ":]" is reserved for future extensions. | |
2881 | If you need to represent those character sequences inside a regular | |
2882 | expression character class, just quote the square brackets with the | |
2883 | backslash: "\[:" and ":\]". | |
2884 | ||
2885 | =item Ill-formed logical name |%s| in prime_env_iter | |
2886 | ||
2887 | (W) A warning peculiar to VMS. A logical name was encountered when preparing | |
2888 | to iterate over %ENV which violates the syntactic rules governing logical | |
2889 | names. Because it cannot be translated normally, it is skipped, and will not | |
2890 | appear in %ENV. This may be a benign occurrence, as some software packages | |
2891 | might directly modify logical name tables and introduce nonstandard names, | |
2892 | or it may indicate that a logical name table has been corrupted. | |
2893 | ||
2894 | =item Probable precedence problem on %s | |
2895 | ||
2896 | (W) The compiler found a bareword where it expected a conditional, | |
2897 | which often indicates that an || or && was parsed as part of the | |
2898 | last argument of the previous construct, for example: | |
2899 | ||
2900 | open FOO || die; | |
2901 | ||
2902 | =item regexp too big | |
2903 | ||
2904 | (F) The current implementation of regular expressions uses shorts as | |
2905 | address offsets within a string. Unfortunately this means that if | |
2906 | the regular expression compiles to longer than 32767, it'll blow up. | |
2907 | Usually when you want a regular expression this big, there is a better | |
2908 | way to do it with multiple statements. See L<perlre>. | |
2909 | ||
2910 | =item Use of "$$<digit>" to mean "${$}<digit>" is deprecated | |
2911 | ||
2912 | (D) Perl versions before 5.004 misinterpreted any type marker followed | |
2913 | by "$" and a digit. For example, "$$0" was incorrectly taken to mean | |
2914 | "${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004. | |
2915 | ||
2916 | However, the developers of Perl 5.004 could not fix this bug completely, | |
2917 | because at least two widely-used modules depend on the old meaning of | |
2918 | "$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the | |
2919 | old (broken) way inside strings; but it generates this message as a | |
2920 | warning. And in Perl 5.005, this special treatment will cease. | |
2921 | ||
2922 | =back | |
2923 | ||
2924 | =head1 Reporting Bugs | |
ba8251e8 | 2925 | |
437784d6 | 2926 | If you find what you think is a bug, you might check the |
14218588 | 2927 | articles recently posted to the comp.lang.perl.misc newsgroup. |
ba8251e8 GS |
2928 | There may also be information at http://www.perl.com/perl/, the Perl |
2929 | Home Page. | |
2930 | ||
2931 | If you believe you have an unreported bug, please run the B<perlbug> | |
642f9deb | 2932 | program included with your release. Be sure to trim your bug down |
ba8251e8 | 2933 | to a tiny but sufficient test case. Your bug report, along with the |
14218588 | 2934 | output of C<perl -V>, will be sent off to perlbug@perl.com to be |
ba8251e8 GS |
2935 | analysed by the Perl porting team. |
2936 | ||
2937 | =head1 SEE ALSO | |
2938 | ||
2939 | The F<Changes> file for exhaustive details on what changed. | |
2940 | ||
2941 | The F<INSTALL> file for how to build Perl. | |
2942 | ||
2943 | The F<README> file for general stuff. | |
2944 | ||
2945 | The F<Artistic> and F<Copying> files for copyright information. | |
2946 | ||
2947 | =head1 HISTORY | |
2948 | ||
a5222a85 GS |
2949 | Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many |
2950 | contributions from The Perl Porters. | |
ba8251e8 GS |
2951 | |
2952 | Send omissions or corrections to <F<perlbug@perl.com>>. | |
2953 | ||
2954 | =cut |