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1=head1 NAME
2
40b7eeef 3perldelta - what's new for perl v5.6 (as of v5.005_64)
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4
5=head1 DESCRIPTION
6
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7This is an unsupported alpha release, meant for intrepid Perl developers
8only. The included sources may not even build correctly on some platforms.
9Subscribing to perl5-porters is the best way to monitor and contribute
10to the progress of development releases (see www.perl.org for info).
11
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12This document describes differences between the 5.005 release and this one.
13
14=head1 Incompatible Changes
15
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16=head2 Perl Source Incompatibilities
17
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18Beware that any new warnings that have been added or old ones
19that have been enhanced are B<not> considered incompatible changes.
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20
21Since all new warnings must be explicitly requested via the C<-w>
22switch or the C<warnings> pragma, it is ultimately the programmer's
23responsibility to ensure that warnings are enabled judiciously.
e02fdbd2 24
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25=over 4
26
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27=item STOP is a new keyword
28
40b7eeef 29In addition to C<BEGIN>, C<INIT>, C<END>, C<DESTROY> and C<AUTOLOAD>,
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30subroutines named C<STOP> are now special. These are queued up during
31compilation and behave similar to END blocks, except they are called at
32the end of compilation rather than at the end of execution. They cannot
33be called directly.
4f25aa18 34
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35=item Treatment of list slices of undef has changed
36
37When taking a slice of a literal list (as opposed to a slice of
38an array or hash), Perl used to return an empty list if the
39result happened to be composed of all undef values.
40
41The new behavior is to produce an empty list if (and only if)
42the original list was empty. Consider the following example:
43
44 @a = (1,undef,undef,2)[2,1,2];
45
46The old behavior would have resulted in @a having no elements.
47The new behavior ensures it has three undefined elements.
48
49Note in particular that the behavior of slices of the following
50cases remains unchanged:
51
52 @a = ()[1,2];
53 @a = (getpwent)[7,0];
54 @a = (anything_returning_empty_list())[2,1,2];
55 @a = @b[2,1,2];
56 @a = @c{'a','b','c'};
57
58See L<perldata>.
59
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60=item Possibly changed pseudo-random number generator
61
62In 5.005_0x and earlier, perl's rand() function used the C library
63rand(3) function. As of 5.005_52, Configure tests for drand48(),
64random(), and rand() (in that order) and picks the first one it finds.
65Perl programs that depend on reproducing a specific set of pseudo-random
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66numbers will now likely produce different output. You can use
67C<sh Configure -Drandfunc=rand> to obtain the old behavior.
757edf6f 68
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69=item Hashing function for hash keys has changed
70
71Perl hashes are not order preserving. The apparently random order
72encountered when iterating on the contents of a hash is determined
73by the hashing algorithm used. To improve the distribution of lower
74bits in the hashed value, the algorithm has changed slightly as of
755.005_52. When iterating over hashes, this may yield a random order
76that is B<different> from that of previous versions.
77
78=item C<undef> fails on read only values
79
80Using the C<undef> operator on a readonly value (such as $1) has
81the same effect as assigning C<undef> to the readonly value--it
82throws an exception.
83
84=item Close-on-exec bit may be set on pipe() handles
85
86On systems that support a close-on-exec flag on filehandles, the
87flag will be set for any handles created by pipe(), if that is
88warranted by the value of $^F that may be in effect. Earlier
89versions neglected to set the flag for handles created with
90pipe(). See L<perlfunc/pipe> and L<perlvar/$^F>.
91
92=item Writing C<"$$1"> to mean C<"${$}1"> is unsupported
93
94Perl 5.004 deprecated the interpretation of C<$$1> and
95similar within interpolated strings to mean C<$$ . "1">,
96but still allowed it.
97
98In Perl 5.6 and later, C<"$$1"> always means C<"${$1}">.
99
94f7643d 100=item delete(), values() and C<\(%h)> operate on aliases to values, not copies
a5222a85 101
94f7643d 102delete(), each(), values() and hashes in a list context return the actual
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103values in the hash, instead of copies (as they used to in earlier
104versions). Typical idioms for using these constructs copy the
501fbaef 105returned values, but this can make a significant difference when
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106creating references to the returned values.
107
108Keys in the hash are still returned as copies when iterating on
08cd8952 109a hash.
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110
111=item vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS
112
08cd8952 113vec() generates a run-time error if the BITS argument is not
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114a valid power-of-two integer.
115
116=item Text of some diagnostic output has changed
117
118Most references to internal Perl operations in diagnostics
119have been changed to be more descriptive. This may be an
120issue for programs that may incorrectly rely on the exact
121text of diagnostics for proper functioning.
122
123=item C<%@> has been removed
124
125The undocumented special variable C<%@> that used to accumulate
126"background" errors (such as those that happen in DESTROY())
127has been removed, because it could potentially result in memory
128leaks.
129
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130=item Parenthesized not() behaves like a list operator
131
132The C<not> operator now falls under the "if it looks like a function,
133it behaves like a function" rule.
134
135As a result, the parenthesized form can be used with C<grep> and C<map>.
136The following construct used to be a syntax error before, but it works
137as expected now:
138
139 grep not($_), @things;
140
141On the other hand, using C<not> with a literal list slice may not
142work. The following previously allowed construct:
143
144 print not (1,2,3)[0];
145
af365420 146needs to be written with additional parentheses now:
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147
148 print not((1,2,3)[0]);
149
150The behavior remains unaffected when C<not> is not followed by parentheses.
151
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152=back
153
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154=head2 C Source Incompatibilities
155
156=over 4
157
158=item C<PERL_POLLUTE>
159
160Release 5.005 grandfathered old global symbol names by providing preprocessor
87275199 161macros for extension source compatibility. As of release 5.6, these
e02fdbd2 162preprocessor definitions are not available by default. You need to explicitly
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163compile perl with C<-DPERL_POLLUTE> to get these definitions. For
164extensions still using the old symbols, this option can be
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165specified via MakeMaker:
166
14218588 167 perl Makefile.PL POLLUTE=1
e02fdbd2 168
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169=item C<PERL_IMPLICIT_CONTEXT>
170
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171PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built
172with one of -Dusethreads, -Dusemultiplicity, or both. It is not
173intended to be enabled by users at this time.
174
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175This new build option provides a set of macros for all API functions
176such that an implicit interpreter/thread context argument is passed to
177every API function. As a result of this, something like C<sv_setsv(foo,bar)>
2c2d71f5 178amounts to a macro invocation that actually translates to something like
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179C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected
180to not have any significant source compatibility issues, the difference
181between a macro and a real function call will need to be considered.
182
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183This means that there B<is> a source compatibility issue as a result of
184this if your extensions attempt to use pointers to any of the Perl API
185functions.
186
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187Note that the above issue is not relevant to the default build of
188Perl, whose interfaces continue to match those of prior versions
189(but subject to the other options described here).
190
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191See L<perlguts/"The Perl API"> for detailed information on the
192ramifications of building Perl using this option.
193
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194=item C<PERL_POLLUTE_MALLOC>
195
14218588 196Enabling Perl's malloc in release 5.005 and earlier caused
86058a2d 197the namespace of system versions of the malloc family of functions to
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198be usurped by the Perl versions, since by default they used the
199same names.
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200
201Besides causing problems on platforms that do not allow these functions to
202be cleanly replaced, this also meant that the system versions could not
203be called in programs that used Perl's malloc. Previous versions of Perl
14218588 204have allowed this behaviour to be suppressed with the HIDEMYMALLOC and
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205EMBEDMYMALLOC preprocessor definitions.
206
87275199 207As of release 5.6, Perl's malloc family of functions have default names
86058a2d 208distinct from the system versions. You need to explicitly compile perl with
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209C<-DPERL_POLLUTE_MALLOC> to get the older behaviour. HIDEMYMALLOC
210and EMBEDMYMALLOC have no effect, since the behaviour they enabled is now
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211the default.
212
213Note that these functions do B<not> constitute Perl's memory allocation API.
214See L<perlguts/"Memory Allocation"> for further information about that.
215
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216=back
217
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218=head2 Compatible C Source API Changes
219
220=over
221
222=item C<PATCHLEVEL> is now C<PERL_VERSION>
223
14218588 224The cpp macros C<PERL_REVISION>, C<PERL_VERSION>, and C<PERL_SUBVERSION>
cceca5ed 225are now available by default from perl.h, and reflect the base revision,
14218588 226patchlevel, and subversion respectively. C<PERL_REVISION> had no
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227prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were
228previously available as C<PATCHLEVEL> and C<SUBVERSION>.
229
14218588 230The new names cause less pollution of the B<cpp> namespace and reflect what
cceca5ed 231the numbers have come to stand for in common practice. For compatibility,
14218588 232the old names are still supported when F<patchlevel.h> is explicitly
cceca5ed 233included (as required before), so there is no source incompatibility
14218588 234from the change.
cceca5ed 235
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236=item Support for C++ exceptions
237
238change#3386, also needs perlguts documentation
239[TODO - Chip Salzenberg <chip@perlsupport.com>]
240
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241=back
242
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243=head2 Binary Incompatibilities
244
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245The default build of this release is binary compatible with the 5.005
246release or its maintenance versions.
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247
248The usethreads or usemultiplicity builds are B<not> binary compatible
249with the corresponding builds in 5.005.
e02fdbd2 250
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251=head1 Installation and Configuration Improvements
252
253=head2 New Configure flags
254
255The following new flags may be enabled on the Configure command line
256by running Configure with C<-Dflag>.
257
258 usemultiplicity
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259
260 uselongdouble
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261 usemorebits
262 uselargefiles
a5222a85 263
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264=head2 -Dusethreads and -Duse64bits now more daring
265
266The Configure options enabling the use of threads and the use of
26764-bitness are now more daring in the sense that they no more have
268an explicit list of operating systems of known threads/64-bit
269capabilities. In other words: if your operating system has the
270necessary APIs, you should be able just to go ahead and use them.
271See also L<"64-bit support">.
272
273=head2 Long Doubles
274
275Some platforms have "long doubles", floating point numbers of even
437784d6 276larger range than ordinary "doubles". To enable using long doubles for
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277Perl's scalars, use -Duselongdouble.
278
279=head2 -Dusemorebits
280
281You can enable both -Duse64bits and -Dlongdouble by -Dusemorebits.
282See also L<"64-bit support">.
283
284=head2 -Duselargefiles
285
286Some platforms support large files, files larger than two gigabytes.
287See L<"Large file support"> for more information.
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288
289=head2 installusrbinperl
290
291You can use "Configure -Uinstallusrbinperl" which causes installperl
292to skip installing perl also as /usr/bin/perl. This is useful if you
293prefer not to modify /usr/bin for some reason or another but harmful
294because many scripts assume to find Perl in /usr/bin/perl.
295
296=head2 SOCKS support
297
298You can use "Configure -Dusesocks" which causes Perl to probe
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299for the SOCKS (v5, not v4) proxy protocol library,
300http://www.socks.nec.com/
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301
302=head2 C<-A> flag
303
304You can "post-edit" the Configure variables using the Configure C<-A>
305flag. The editing happens immediately after the platform specific
306hints files have been processed but before the actual configuration
307process starts. Run C<Configure -h> to find out the full C<-A> syntax.
308
c35dd67d 309=head2 Enhanced Installation Directories
67d3893f 310
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311The installation structure has been enriched to improve the support for
312maintaining multiple versions of perl, to provide locations for
313vendor-supplied modules and scripts, and to ease maintenance of
314locally-added modules and scripts. See the section on Installation
315Directories in the INSTALL file for complete details. For most users
316building and installing from source, the defaults should be fine.
67d3893f 317
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318=head1 Core Changes
319
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320=head2 Unicode and UTF-8 support
321
322Perl can optionally use UTF-8 as its internal representation for character
a5222a85 323strings. The C<utf8> pragma enables this support in the current lexical
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324scope. See L<utf8> for more information.
325
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326=head2 Interpreter threads
327
328WARNING: This is an experimental feature in a pre-alpha state. Use
329at your own risk.
330
331Perl 5.005_63 introduces the beginnings of support for running multiple
332interpreters concurrently in different threads. In conjunction with
333the perl_clone() API call, which can be used to selectively duplicate
334the state of any given interpreter, it is possible to compile a
335piece of code once in an interpreter, clone that interpreter
336one or more times, and run all the resulting interpreters in distinct
337threads.
338
339On Windows, this feature is used to emulate fork() at the interpreter
340level. See L<perlfork>.
341
342This feature is still in evolution. It is eventually meant to be used
343to selectively clone a subroutine and data reachable from that
344subroutine in a separate interpreter and run the cloned subroutine
345in a separate thread. Since there is no shared data between the
346interpreters, little or no locking will be needed (unless parts of
347the symbol table are explicitly shared). This is obviously intended
348to be an easy-to-use replacement for the existing threads support.
349
350Support for cloning interpreters must currently be manually enabled
351by defining the cpp macro USE_ITHREADS on non-Windows platforms.
352(See win32/Makefile for how to enable it on Windows.) The resulting
353perl executable will be functionally identical to one that was built
354without USE_ITHREADS, but the perl_clone() API call will only be
355available in the former.
356
357USE_ITHREADS enables Perl source code changes that provide a clear
358separation between the op tree and the data it operates with. The
359former is considered immutable, and can therefore be shared between
360an interpreter and all of its clones, while the latter is considered
361local to each interpreter, and is therefore copied for each clone.
362
363Note that building Perl with the -Dusemultiplicity Configure option
364is adequate if you wish to run multiple B<independent> interpreters
365concurrently in different threads. USE_ITHREADS only needs to be
366enabled if you wish to obtain access to perl_clone() and cloned
367interpreters.
368
369[XXX TODO - the Compiler backends may be broken when USE_ITHREADS is
370enabled.]
371
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372=head2 Lexically scoped warning categories
373
374You can now control the granularity of warnings emitted by perl at a finer
4438c4b7 375level using the C<use warnings> pragma. See L<warnings> and L<perllexwarn>
0453d815 376for details.
9d73390d 377
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378=head2 Lvalue subroutines
379
380WARNING: This is an experimental feature.
381
382change#4081
383[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>,
384Tuomas Lukka <lukka@fas.harvard.edu>)]
385
386=head2 "our" declarations
387
388An "our" declaration introduces a value that can be best understood
389as a lexically scoped symbolic alias to a global variable in the
390current package. This is mostly useful as an alternative to the
391C<vars> pragma, but also provides the opportunity to introduce
392typing and other attributes for such variables. See L<perlfunc/our>.
393
394=head2 Weak references
395
396WARNING: This is an experimental feature.
397
398change#3385, also need perlguts documentation
399
400[TODO - Tuomas Lukka <lukka@fas.harvard.edu>]
401
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402=head2 File globbing implemented internally
403
404WARNING: This is currently an experimental feature. Interfaces and
405implementation are likely to change.
406
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407Perl now uses the File::Glob implementation of the glob() operator
408automatically. This avoids using an external csh process and the
409problems associated with it.
becf2bd3 410
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411=head2 Binary numbers supported
412
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413Binary numbers are now supported as literals, in s?printf formats, and
414C<oct()>:
415
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416 $answer = 0b101010;
417 printf "The answer is: %b\n", oct("0b101010");
4f19785b 418
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419=head2 Some arrows may be omitted in calls through references
420
421Perl now allows the arrow to be omitted in many constructs
422involving subroutine calls through references. For example,
423C<$foo[10]->('foo')> may now be written C<$foo[10]('foo')>.
424This is rather similar to how the arrow may be omitted from
425C<$foo[10]->{'foo'}>. Note however, that the arrow is still
426required for C<foo(10)->('bar')>.
427
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428=head2 exists() is supported on subroutine names
429
430The exists() builtin now works on subroutine names. A subroutine
431is considered to exist if it has been declared (even if implicitly).
432See L<perlfunc/exists> for examples.
433
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434=head2 exists() and delete() are supported on array elements
435
436The exists() and delete() builtins now work on simple arrays as well.
437The behavior is similar to that on hash elements.
438
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439exists() can be used to check whether an array element has been
440initialized without autovivifying it. If the array is tied, the
441EXISTS() method in the corresponding tied package will be invoked.
442
443delete() may be used to remove an element from the array and return
444it. The array element at that position returns to its unintialized
445state, so that testing for the same element with exists() will return
446false. If the element happens to be the one at the end, the size of
447the array also shrinks by one. If the array is tied, the DELETE() method
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448in the corresponding tied package will be invoked.
449
450See L<perlfunc/exists> and L<perlfunc/delete> for examples.
451
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452=head2 syswrite() ease-of-use
453
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454The length argument of C<syswrite()> has become optional.
455
b1a9ed4a 456=head2 File and directory handles can be autovivified
a5222a85 457
2c8ac474 458Similar to how constructs such as C<$x->[0]> autovivify a reference,
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459handle constructors (open(), opendir(), pipe(), socketpair(), sysopen(),
460socket(), and accept()) now autovivify a file or directory handle
461if the handle passed to them is an uninitialized scalar variable. This
462allows the constructs such as C<open(my $fh, ...)> and C<open(local $fh,...)>
463to be used to create filehandles that will conveniently be closed
464automatically when the scope ends, provided there are no other references
465to them. This largely eliminates the need for typeglobs when opening
466filehandles that must be passed around, as in the following example:
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467
468 sub myopen {
469 open my $fh, "@_"
470 or die "Can't open '@_': $!";
471 return $fh;
472 }
473
474 {
475 my $f = myopen("</etc/motd");
476 print <$f>;
477 # $f implicitly closed here
478 }
479
480[TODO - this idiom needs more pod penetration]
6c67e1bb 481
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482=head2 64-bit support
483
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484All platforms that have 64-bit integers either (a) natively as longs
485or ints (b) via special compiler flags (c) using long long are able to
486use "quads" (64-integers) as follows:
487
488=over 4
489
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490=item *
491
492constants (decimal, hexadecimal, octal, binary) in the code
493
494=item *
9c107f78 495
a5222a85 496arguments to oct() and hex()
9c107f78 497
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498=item *
499
500arguments to print(), printf() and sprintf() (flag prefixes ll, L, q)
501
502=item *
9c107f78 503
a5222a85 504printed as such
9c107f78 505
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506=item *
507
508pack() and unpack() "q" and "Q" formats
509
510=item *
511
512in basic arithmetics: + - * / %
513
514=item *
1fad5d67 515
a5222a85 516vec() (but see the below note about bit arithmetics)
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517
518=back
519
520Note that unless you have the case (a) you will have to configure
521and compile Perl using the -Duse64bits Configure flag.
522
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523Unfortunately bit arithmetics (&, |, ^, ~, <<, >>) for numbers are not
52464-bit clean, they are explictly forced to be 32-bit. Bit arithmetics
525for bit vectors (created by vec()) are not limited in their width.
d0ba1bd2 526
2d4389e4 527Last but not least: note that due to Perl's habit of always using
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528floating point numbers the quads are still not true integers.
529When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned,
530-9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they
531are silently promoted to floating point numbers, after which they will
532start losing precision (their lower digits).
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533
534=head2 Large file support
535
536If you have filesystems that support "large files" (files larger than
aa855319 5372 gigabytes), you may now also be able to create and access them from
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538Perl. You have to use Configure -Duselargefiles. Turning on the
539large file support turns on also the 64-bit support, for obvious reasons.
2d4389e4 540
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541Note that in addition to requiring a proper file system to do large
542files you may also need to adjust your per-process (or your
543per-system, or per-process-group, or per-user-group) maximum filesize
544limits before running Perl scripts that try to handle large files,
545especially if you intend to write such files.
546
547Finally, in addition to your process/process group maximum filesize
548limits, you may have quota limits on your filesystems that stop you
549(your user id or your user group id) from using large files.
550
551Adjusting your process/user/group/file system/operating system limits
552is outside the scope of Perl core language. For process limits, you
553may try increasing the limits using your shell's limits/limit/ulimit
554command before running Perl. The BSD::Resource extension (not
555included with the standard Perl distribution) may also be of use, it
556offers the getrlimit/setrlimit interface that can be used to adjust
557process resource usage limits, including the maximum filesize limit.
475d79b5 558
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559=head2 Long doubles
560
561In some systems you may be able to use long doubles to enhance the
562range of precision of your double precision floating point numbers
563(that is, Perl's numbers). Use Configure -Duselongdouble to enable
564this support (if it is available).
565
566=head2 "more bits"
567
568You can Configure -Dusemorebits to turn on both the 64-bit support
569and the long double support.
09bef843 570
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571=head2 Enhanced support for sort() subroutines
572
573Perl subroutines with a prototype of C<($$)> and XSUBs in general can
574now be used as sort subroutines. In either case, the two elements to
af365420 575be compared are passed as normal parameters in @_. See L<perlfunc/sort>.
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576
577For unprototyped sort subroutines, the historical behavior of passing
578the elements to be compared as the global variables $a and $b remains
579unchanged.
580
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581=head2 Better syntax checks on parenthesized unary operators
582
583Expressions such as:
584
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585 print defined(&foo,&bar,&baz);
586 print uc("foo","bar","baz");
587 undef($foo,&bar);
62c18ce2 588
7711098a 589used to be accidentally allowed in earlier versions, and produced
14218588
GS
590unpredictable behaviour. Some produced ancillary warnings
591when used in this way; others silently did the wrong thing.
62c18ce2
GS
592
593The parenthesized forms of most unary operators that expect a single
14218588
GS
594argument now ensure that they are not called with more than one
595argument, making the cases shown above syntax errors. The usual
596behaviour of:
62c18ce2 597
14218588
GS
598 print defined &foo, &bar, &baz;
599 print uc "foo", "bar", "baz";
600 undef $foo, &bar;
62c18ce2
GS
601
602remains unchanged. See L<perlop>.
603
3e3318e7
GS
604=head2 POSIX character class syntax [: :] supported
605
606For example to match alphabetic characters use /[[:alpha:]]/.
607See L<perlre> for details.
608
5a929a98 609=head2 Improved C<qw//> operator
8127e0e3 610
26ef7447
GS
611The C<qw//> operator is now evaluated at compile time into a true list
612instead of being replaced with a run time call to C<split()>. This
14218588
GS
613removes the confusing misbehaviour of C<qw//> in scalar context, which
614had inherited that behaviour from split().
26ef7447
GS
615
616Thus:
617
618 $foo = ($bar) = qw(a b c); print "$foo|$bar\n";
619
620now correctly prints "3|a", instead of "2|a".
8127e0e3 621
5a929a98
VU
622=head2 pack() format 'Z' supported
623
624The new format type 'Z' is useful for packing and unpacking null-terminated
625strings. See L<perlfunc/"pack">.
626
4d0c1c44 627=head2 pack() format modifier '!' supported
ee3907e2 628
14218588 629The new format type modifier '!' is useful for packing and unpacking
ee3907e2
JH
630native shorts, ints, and longs. See L<perlfunc/"pack">.
631
f29c64d6
GS
632=head2 pack() and unpack() support counted strings
633
a5222a85 634The template character '/' can be used to specify a counted string
f29c64d6
GS
635type to be packed or unpacked. See L<perlfunc/"pack">.
636
a5222a85
GS
637=head2 Comments in pack() templates
638
639The '#' character in a template introduces a comment up to
640end of the line. This facilitates documentation of pack()
641templates.
642
2b92dfce
GS
643=head2 $^X variables may now have names longer than one character
644
645Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax
646error. Now variable names that begin with a control character may be
647arbitrarily long. However, for compatibility reasons, these variables
648I<must> be written with explicit braces, as C<${^XY}> for example.
14218588 649C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more
2b92dfce
GS
650than one control character, such as C<${^XY^Z}>, are illegal.
651
14218588
GS
652The old syntax has not changed. As before, `^X' may be either a
653literal control-X character or the two-character sequence `caret' plus
654`X'. When braces are omitted, the variable name stops after the
2b92dfce 655control character. Thus C<"$^XYZ"> continues to be synonymous with
7711098a 656C<$^X . "YZ"> as before.
2b92dfce
GS
657
658As before, lexical variables may not have names beginning with control
659characters. As before, variables whose names begin with a control
14218588
GS
660character are always forced to be in package `main'. All such variables
661are reserved for future extensions, except those that begin with
09bef843 662C<^_>, which may be used by user programs and are guaranteed not to
14218588 663acquire special meaning in any future version of Perl.
2b92dfce 664
09bef843
SB
665=head2 C<use attrs> implicit in subroutine attributes
666
667Formerly, if you wanted to mark a subroutine as being a method call or
668as requiring an automatic lock() when it is entered, you had to declare
669that with a C<use attrs> pragma in the body of the subroutine.
670That can now be accomplished with a declaration syntax, like this:
671
672 sub mymethod : locked, method ;
673 ...
674 sub mymethod : locked, method {
675 ...
676 }
677
678F<AutoSplit.pm> and F<SelfLoader.pm> have been updated to keep the attributes
679with the stubs they provide. See L<attributes>.
680
a5222a85
GS
681=head2 Regular expression improvements
682
683change#2827,2373,2372,2365,1813,1800,4112,4158,4215,4301
684[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
685
686=head2 Overloading improvements
687
688change#2150
689[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
690
691=head2 open() with more than two arguments
692
693[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
694
695=head2 Support for interpolating named characters
696
697change#4052
698[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
699
08cd8952 700=head2 Experimental support for user-hooks in @INC
a5222a85
GS
701
702[TODO - Ken Fox <kfox@ford.com>]
703
704=head2 C<require> and C<do> may be overridden
705
706C<require> and C<do 'file'> operations may be overridden locally
707by importing subroutines of the same name into the current package
708(or globally by importing them into the CORE::GLOBAL:: namespace).
709Overriding C<require> will also affect C<use>, provided the override
710is visible at compile-time.
711See L<perlsub/"Overriding Built-in Functions">.
712
713=head2 New variable $^C reflects C<-c> switch
714
08cd8952 715C<$^C> has a boolean value that reflects whether perl is being run
a5222a85
GS
716in compile-only mode (i.e. via the C<-c> switch). Since
717BEGIN blocks are executed under such conditions, this variable
718enables perl code to determine whether actions that make sense
719only during normal running are warranted. See L<perlvar>.
720
721=head2 Optional Y2K warnings
722
723If Perl is built with the cpp macro C<PERL_Y2KWARN> defined,
724it emits optional warnings when concatenating the number 19
725with another number.
726
727This behavior must be specifically enabled when running Configure.
728See L<INSTALL> and L<README.Y2K>.
729
fbad3eb5
GS
730=head1 Significant bug fixes
731
732=head2 E<lt>HANDLEE<gt> on empty files
733
734With C<$/> set to C<undef>, slurping an empty file returns a string of
14218588
GS
735zero length (instead of C<undef>, as it used to) the first time the
736HANDLE is read. Further reads yield C<undef>.
fbad3eb5
GS
737
738This means that the following will append "foo" to an empty file (it used
14218588 739to do nothing):
fbad3eb5
GS
740
741 perl -0777 -pi -e 's/^/foo/' empty_file
742
14218588 743The behaviour of:
fbad3eb5
GS
744
745 perl -pi -e 's/^/foo/' empty_file
746
747is unchanged (it continues to leave the file empty).
748
0244c3a4
GS
749=head2 C<eval '...'> improvements
750
751Line numbers (as reflected by caller() and most diagnostics) within
752C<eval '...'> were often incorrect when here documents were involved.
753This has been corrected.
754
755Lexical lookups for variables appearing in C<eval '...'> within
756functions that were themselves called within an C<eval '...'> were
14218588
GS
757searching the wrong place for lexicals. The lexical search now
758correctly ends at the subroutine's block boundary.
0244c3a4
GS
759
760Parsing of here documents used to be flawed when they appeared as
761the replacement expression in C<eval 's/.../.../e'>. This has
762been fixed.
763
a5222a85
GS
764=head2 All compilation errors are true errors
765
766Some "errors" encountered at compile time were by neccessity
767generated as warnings followed by eventual termination of the
768program. This enabled more such errors to be reported in a
769single run, rather than causing a hard stop at the first error
770that was encountered.
771
772The mechanism for reporting such errors has been reimplemented
773to queue compile-time errors and report them at the end of the
774compilation as true errors rather than as warnings. This fixes
08cd8952
GS
775cases where error messages leaked through in the form of warnings
776when code was compiled at run time using C<eval STRING>, and
777also allows such errors to be reliably trapped using __DIE__ hooks.
a5222a85 778
45bc9206
GS
779=head2 Automatic flushing of output buffers
780
14218588
GS
781fork(), exec(), system(), qx//, and pipe open()s now flush buffers
782of all files opened for output when the operation
783was attempted. This mostly eliminates confusing
45bc9206 784buffering mishaps suffered by users unaware of how Perl internally
14218588 785handles I/O.
45bc9206 786
af8c498a
GS
787=head2 Better diagnostics on meaningless filehandle operations
788
789Constructs such as C<open(E<lt>FHE<gt>)> and C<close(E<lt>FHE<gt>)>
790are compile time errors. Attempting to read from filehandles that
791were opened only for writing will now produce warnings (just as
792writing to read-only filehandles does).
793
a5222a85
GS
794=head2 Where possible, buffered data discarded from duped input filehandle
795
796C<open(NEW, "E<lt>&OLD")> now attempts to discard any data that
797was previously read and buffered in C<OLD> before duping the handle.
798On platforms where doing this is allowed, the next read operation
799on C<NEW> will return the same data as the corresponding operation
800on C<OLD>. Formerly, it would have returned the data from the start
801of the following disk block instead.
802
820475bd
GS
803=head2 eof() has the same old magic as <>
804
805C<eof()> would return true if no attempt to read from C<E<lt>E<gt>> had
806yet been made. C<eof()> has been changed to have a little magic of its
807own, it now opens the C<E<lt>E<gt>> files.
808
a5222a85
GS
809=head2 system(), backticks and pipe open now reflect exec() failure
810
811On Unix and similar platforms, system(), qx() and open(FOO, "cmd |")
812etc., are implemented via fork() and exec(). When the underlying
813exec() fails, earlier versions did not report the error properly,
814since the exec() happened to be in a different process.
815
816The child process now communicates with the parent about the
437784d6 817error in launching the external command, which allows these
a5222a85
GS
818constructs to return with their usual error value and set $!.
819
820=head2 Implicitly closed filehandles are safer
821
822Sometimes implicitly closed filehandles (as when they are localized,
823and Perl automatically closes them on exiting the scope) could
824inadvertently set $? or $!. This has been corrected.
825
826=head2 C<(\$)> prototype and C<$foo{a}>
827
828An scalar reference prototype now correctly allows a hash or
829array element in that slot.
830
831=head2 Pseudo-hashes work better
832
833Dereferencing some types of reference values in a pseudo-hash,
834such as C<$ph->{foo}[1]>, was accidentally disallowed. This has
835been corrected.
836
837When applied to a pseudo-hash element, exists() now reports whether
838the specified value exists, not merely if the key is valid.
839
01020589
GS
840delete() now works on pseudo-hashes. When given a pseudo-hash element
841or slice it deletes the values corresponding to the keys (but not the keys
842themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">.
843
a5222a85
GS
844=head2 C<goto &sub> and AUTOLOAD
845
08cd8952 846The C<goto &sub> construct works correctly when C<&sub> happens
a5222a85
GS
847to be autoloaded.
848
849=head2 C<-bareword> allowed under C<use integer>
850
851The autoquoting of barewords preceded by C<-> did not work
852in prior versions when the C<integer> pragma was enabled.
853This has been fixed.
854
855=head2 Boolean assignment operators are legal lvalues
856
857Constructs such as C<($a ||= 2) += 1> are now allowed.
858
859=head2 C<sort $coderef @foo> allowed
860
861sort() did not accept a subroutine reference as the comparison
08cd8952 862function in earlier versions. This is now permitted.
a5222a85
GS
863
864=head2 Failures in DESTROY()
865
866When code in a destructor threw an exception, it went unnoticed
867in earlier versions of Perl, unless someone happened to be
868looking in $@ just after the point the destructor happened to
869run. Such failures are now visible as warnings when warnings are
870enabled.
871
872=head2 Locale bugs fixed
54195c32 873
437784d6 874printf() and sprintf() previously reset the numeric locale
67d3893f
JH
875back to the default "C" locale. This has been fixed.
876
877Numbers formatted according to the local numeric locale
878(such as using a decimal comma instead of a decimal dot) caused
879"isn't numeric" warnings, even while the operations accessing
880those numbers produced correct results. The warnings are gone.
54195c32 881
a5222a85
GS
882=head2 Memory leaks
883
884The C<eval 'return sub {...}'> construct could sometimes leak
885memory. This has been fixed.
886
887Operations that aren't filehandle constructors used to leak memory
888when used on invalid filehandles. This has been fixed.
889
890Constructs that modified C<@_> could fail to deallocate values
891in C<@_> and thus leak memory. This has been corrected.
892
893=head2 Spurious subroutine stubs after failed subroutine calls
894
895Perl could sometimes create empty subroutine stubs when a
896subroutine was not found in the package. Such cases stopped
897later method lookups from progressing into base packages.
898This has been corrected.
899
900=head2 Consistent numeric conversions
901
902change#3378,3318
903[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
904
905=head2 Taint failures under C<-U>
906
907When running in unsafe mode, taint violations could sometimes
908cause silent failures. This has been fixed.
909
910=head2 END blocks and the C<-c> switch
911
912Prior versions used to run BEGIN B<and> END blocks when Perl was
913run in compile-only mode. Since this is typically not the expected
08cd8952 914behavior, END blocks are not executed anymore when the C<-c> switch
a5222a85
GS
915is used.
916
4f25aa18 917See L<STOP blocks> for how to run things when the compile phase ends.
a5222a85
GS
918
919=head2 Potential to leak DATA filehandles
920
921Using the C<__DATA__> token creates an implicit filehandle to
922the file that contains the token. It is the program's
923responsibility to close it when it is done reading from it.
924
925This caveat is now better explained in the documentation.
926See L<perldata>.
927
928=head2 Diagnostics follow STDERR
929
930Diagnostic output now goes to whichever file the C<STDERR> handle
931is pointing at, instead of always going to the underlying C runtime
932library's C<stderr>.
933
934=head2 Other fixes for better diagnostics
935
437784d6 936Line numbers are no longer suppressed (under most likely circumstances)
a5222a85
GS
937during the global destruction phase.
938
939Diagnostics emitted from code running in threads other than the main
940thread are now accompanied by the thread ID.
941
942Embedded null characters in diagnostics now actually show up. They
943used to truncate the message in prior versions.
944
945$foo::a and $foo::b are now exempt from "possible typo" warnings only
946if sort() is encountered in package foo.
947
501fbaef 948Unrecognized alphabetic escapes encountered when parsing quote
a5222a85
GS
949constructs now generate a warning, since they may take on new
950semantics in later versions of Perl.
951
952=head1 Performance enhancements
953
954=head2 Simple sort() using { $a <=> $b } and the like are optimized
955
08cd8952 956Many common sort() operations using a simple inlined block are now
a5222a85
GS
957optimized for faster performance.
958
959=head2 Optimized assignments to lexical variables
960
961Certain operations in the RHS of assignment statements have been
962optimized to directly set the lexical variable on the LHS,
963eliminating redundant copying overheads.
964
965=head2 Method lookups optimized
966
967[TODO - Chip Salzenberg <chip@perlsupport.com>]
968
969=head2 Faster mechanism to invoke XSUBs
970
971change#4044,4125
972[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
973
974=head2 Perl_malloc() improvements
975
976change#4237
977[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
978
979=head2 Faster subroutine calls
980
981Minor changes in how subroutine calls are handled internally
982provide marginal improvements in performance.
983
984=head1 Platform specific changes
985
986=head2 Additional supported platforms
ba8251e8 987
5fdc711f
GS
988=over 4
989
990=item *
991
6c67e1bb
TC
992VM/ESA is now supported.
993
5fdc711f
GS
994=item *
995
ee3907e2
JH
996Siemens BS2000 is now supported under the POSIX Shell.
997
998=item *
999
2bb14304
JH
1000The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread
1001extension.
6c67e1bb 1002
5fdc711f
GS
1003=item *
1004
ee3907e2 1005GNU/Hurd is now supported.
6c67e1bb 1006
00ad96e1
JH
1007=item *
1008
1009Rhapsody is now supported.
1010
27806c82
JH
1011=item *
1012
1013EPOC is is now supported (on Psion 5).
1014
5fdc711f
GS
1015=back
1016
a5222a85
GS
1017=head2 DOS
1018
d524f05e
LM
1019=over 4
1020
1021=item *
1022
1023Perl now works with djgpp 2.02 (and 2.03 alpha).
1024
1025=item *
1026
1027Environment variable names are not converted to uppercase any more.
1028
1029=item *
1030
1031Wrong exit code from backticks now fixed.
1032
1033=item *
1034
1035This port is still using its own builtin globbing.
1036
1037=back
a5222a85
GS
1038
1039=head2 OS/2
1040
1041[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
1042
1043=head2 VMS
1044
1045[TODO - Charles Bailey <bailey@newman.upenn.edu>]
1046
1047=head2 Win32
1048
1049Site library searches failed to look for ".../site/5.XXX/lib"
1050if ".../site/5.XXXYY/lib" wasn't found. This has been corrected.
1051
1052When given a pathname that consists only of a drivename, such
1053as C<A:>, opendir() and stat() now use the current working
1054directory for the drive rather than the drive root.
1055
1056The builtin XSUB functions in the Win32:: namespace are
1057documented. See L<Win32>.
1058
1059$^X now contains the full path name of the running executable.
1060
1061A Win32::GetLongPathName() function is provided to complement
1062Win32::GetFullPathName() and Win32::GetShortPathName(). See L<Win32>.
1063
1064POSIX::uname() is supported.
1065
1066system(1,...) now returns true process IDs rather than process
1067handles. kill() accepts any real process id, rather than strictly
1068return values from system(1,...).
1069
1070The C<Shell> module is supported.
1071
883d36a6
GS
1072Rudimentary support for building under command.com in Windows 95
1073has been added.
1074
c39cd008
GS
1075Scripts are read in binary mode by default to allow ByteLoader (and
1076the filter mechanism in general) to work properly. For compatibility,
53129d29
GS
1077the DATA filehandle will be set to text mode if a carriage return is
1078detected at the end of the line containing the __END__ or __DATA__
1079token; if not, the DATA filehandle will be left open in binary mode.
1080Earlier versions always opened the DATA filehandle in text mode.
c39cd008 1081
a5222a85
GS
1082[TODO - GSAR]
1083
6c67e1bb
TC
1084=head1 New tests
1085
1086=over 4
1087
09bef843
SB
1088=item lib/attrs
1089
1090Compatibility tests for C<sub : attrs> vs the older C<use attrs>.
1091
1092=item lib/io_const
6c67e1bb
TC
1093
1094IO constants (SEEK_*, _IO*).
14218588 1095
09bef843 1096=item lib/io_dir
6c67e1bb
TC
1097
1098Directory-related IO methods (new, read, close, rewind, tied delete).
1099
09bef843 1100=item lib/io_multihomed
6c67e1bb
TC
1101
1102INET sockets with multi-homed hosts.
1103
09bef843 1104=item lib/io_poll
6c67e1bb
TC
1105
1106IO poll().
1107
09bef843 1108=item lib/io_unix
6c67e1bb
TC
1109
1110UNIX sockets.
1111
09bef843
SB
1112=item op/attrs
1113
1114Regression tests for C<my ($x,@y,%z) : attrs> and <sub : attrs>.
1115
6c67e1bb
TC
1116=item op/filetest
1117
1118File test operators.
1119
1120=item op/lex_assign
1121
5fdc711f 1122Verify operations that access pad objects (lexicals and temporaries).
6c67e1bb 1123
afebc493
GS
1124=item op/exists_sub
1125
1126Verify C<exists &sub> operations.
1127
6c67e1bb 1128=back
e02fdbd2 1129
ba8251e8
GS
1130=head1 Modules and Pragmata
1131
3e8c4fa0
JH
1132=head2 Modules
1133
b7d8191e
JH
1134=over 4
1135
09bef843
SB
1136=item attributes
1137
1138While used internally by Perl as a pragma, this module also
1139provides a way to fetch subroutine and variable attributes.
1140See L<attributes>.
1141
a5222a85
GS
1142=item B
1143
501fbaef
GS
1144The Perl Compiler suite has been extensively reworked for this
1145release.
1146
a5222a85
GS
1147[TODO - Vishal Bhatia <vishal@gol.com>,
1148Nick Ing-Simmons <nick@ni-s.u-net.com>]
1149
f29c64d6
GS
1150=item ByteLoader
1151
a5222a85 1152The ByteLoader is a dedicated extension to generate and run
f29c64d6
GS
1153Perl bytecode. See L<ByteLoader>.
1154
a5222a85
GS
1155=item constant
1156
83763826
GS
1157References can now be used.
1158
1159The new version also allows a leading underscore in constant names, but
1160disallows a double leading underscore (as in "__LINE__"). Some other names
1161are disallowed or warned against, including BEGIN, END, etc. Some names
1162which were forced into main:: used to fail silently in some cases; now they're
1163fatal (outside of main::) and an optional warning (inside of main::).
1164The ability to detect whether a constant had been set with a given name has
1165been added.
1166
1167See L<constant>.
a5222a85
GS
1168
1169=item charnames
1170
1171change#4052
1172[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
1173
1174=item Data::Dumper
1175
1176A C<Maxdepth> setting can be specified to avoid venturing
73b437c8 1177too deeply into deep data structures. See L<Data::Dumper>.
a5222a85
GS
1178
1179Dumping C<qr//> objects works correctly.
1180
1181=item DB
1182
1183C<DB> is an experimental module that exposes a clean abstraction
1184to Perl's debugging API.
1185
1186=item DB_File
1187
0536e0eb
GS
1188DB_File can now be built with Berkeley DB versions 1, 2 or 3.
1189See C<ext/DB_File/Changes>.
a5222a85 1190
f29c64d6
GS
1191=item Devel::DProf
1192
9e107c59
GS
1193Devel::DProf, a Perl source code profiler has been added. See
1194L<Devel::DProf> and L<dprofpp>.
f29c64d6 1195
b7d8191e
JH
1196=item Dumpvalue
1197
437784d6 1198The Dumpvalue module provides screen dumps of Perl data.
b7d8191e
JH
1199
1200=item Benchmark
1201
54e82ce5
GS
1202Overall, Benchmark results exhibit lower average error and better timing
1203accuracy.
1204
868cb350 1205You can now run tests for I<n> seconds instead of guessing the right
14218588
GS
1206number of tests to run: e.g. timethese(-5, ...) will run each
1207code for at least 5 CPU seconds. Zero as the "number of repetitions"
155776c0 1208means "for at least 3 CPU seconds". The output format has also
14218588 1209changed. For example:
155776c0 1210
54e82ce5 1211 use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
155776c0
JH
1212
1213will now output something like this:
1214
54e82ce5
GS
1215 Benchmark: running a, b, each for at least 5 CPU seconds...
1216 a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516)
1217 b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
155776c0
JH
1218
1219New features: "each for at least N CPU seconds...", "wallclock secs",
1220and the "@ operations/CPU second (n=operations)".
b7d8191e 1221
54e82ce5
GS
1222timethese() now returns a reference to a hash of Benchmark objects containing
1223the test results, keyed on the names of the tests.
1224
1225timethis() now returns the iterations field in the Benchmark result object
1226instead of 0.
1227
1228timethese(), timethis(), and the new cmpthese() (see below) can also take
1229a format specifier of 'none' to suppress output.
1230
1231A new function countit() is just like timeit() except that it takes a
1232TIME instead of a COUNT.
1233
1234A new function cmpthese() prints a chart comparing the results of each test
1235returned from a timethese() call. For each possible pair of tests, the
1236percentage speed difference (iters/sec or seconds/iter) is shown.
1237
1238For other details, see L<Benchmark>.
a5222a85 1239
f505c983
GS
1240=item Devel::Peek
1241
1242The Devel::Peek module provides access to the internal representation
14218588 1243of Perl variables and data. It is a data debugging tool for the XS programmer.
f505c983 1244
a5222a85
GS
1245=item ExtUtils::MakeMaker
1246
1247change#4135, also needs docs in module pod
1248[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
1249
b7d8191e
JH
1250=item Fcntl
1251
1252More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
14218588 1253large (more than 4G) file access (64-bit support is not yet
b7d8191e
JH
1254working, though, so no need to get overly excited), Free/Net/OpenBSD
1255locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
1256O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
1257
a5222a85
GS
1258=item File::Compare
1259
1260A compare_text() function has been added, which allows custom
1261comparison functions. See L<File::Compare>.
1262
1263=item File::Find
1264
1265File::Find now works correctly when the wanted() function is either
1266autoloaded or is a symbolic reference.
1267
08cd8952 1268A bug that caused File::Find to lose track of the working directory
a5222a85
GS
1269when pruning top-level directories has been fixed.
1270
81793b90
GS
1271File::Find now also supports several other options to control its
1272behavior. It can follow symbolic links if the C<follow> option is
1273specified. Enabling the C<no_chdir> option will make File::Find skip
1274changing the current directory when walking directories. The C<untaint>
1275flag can be useful when running with taint checks enabled.
1276
1277See L<File::Find>.
1278
becf2bd3
GS
1279=item File::Glob
1280
52bb0670
GS
1281This extension implements BSD-style file globbing. By default,
1282it will also be used for the internal implementation of the glob()
1283operator. See L<File::Glob>.
becf2bd3 1284
f505c983
GS
1285=item File::Spec
1286
1287New methods have been added to the File::Spec module: devnull() returns
19799a22 1288the name of the null device (/dev/null on Unix) and tmpdir() the name of
14218588 1289the temp directory (normally /tmp on Unix). There are now also methods
f505c983 1290to convert between absolute and relative filenames: abs2rel() and
14218588
GS
1291rel2abs(). For compatibility with operating systems that specify volume
1292names in file paths, the splitpath(), splitdir(), and catdir() methods
f505c983
GS
1293have been added.
1294
1295=item File::Spec::Functions
1296
1297The new File::Spec::Functions modules provides a function interface
14218588 1298to the File::Spec module. Allows shorthand
f505c983 1299
14218588 1300 $fullname = catfile($dir1, $dir2, $file);
f505c983
GS
1301
1302instead of
1303
14218588 1304 $fullname = File::Spec->catfile($dir1, $dir2, $file);
f505c983 1305
a5222a85
GS
1306=item Getopt::Long
1307
c6edd1b7
GS
1308Getopt::Long licensing has changed to allow the Perl Artistic License
1309as well as the GPL. It used to be GPL only, which got in the way of
1310non-GPL applications that wanted to use Getopt::Long.
1311
1312Getopt::Long encourages the use of Pod::Usage to produce help
1313messages. For example:
1314
1315 use Getopt::Long;
1316 use Pod::Usage;
1317 my $man = 0;
1318 my $help = 0;
1319 GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
1320 pod2usage(1) if $help;
1321 pod2usage(-exitstatus => 0, -verbose => 2) if $man;
1322
1323 __END__
1324
1325 =head1 NAME
1326
1327 sample - Using GetOpt::Long and Pod::Usage
1328
1329 =head1 SYNOPSIS
1330
1331 sample [options] [file ...]
1332
1333 Options:
1334 -help brief help message
1335 -man full documentation
1336
1337 =head1 OPTIONS
1338
1339 =over 8
1340
1341 =item B<-help>
1342
1343 Print a brief help message and exits.
1344
1345 =item B<-man>
1346
1347 Prints the manual page and exits.
1348
1349 =back
1350
1351 =head1 DESCRIPTION
1352
1353 B<This program> will read the given input file(s) and do someting
1354 useful with the contents thereof.
1355
1356 =cut
1357
1358See L<Pod::Usage> for details.
1359
1360A bug that prevented the non-option call-back E<lt>E<gt> from being
1361specified as the first argument has been fixed.
1362
1363To specify the characters E<lt> and E<gt> as option starters, use
1364E<gt>E<lt>. Note, however, that changing option starters is strongly
1365deprecated.
a5222a85
GS
1366
1367=item IO
1368
1369write() and syswrite() will now accept a single-argument
1370form of the call, for consistency with Perl's syswrite().
1371
1372You can now create a TCP-based IO::Socket::INET without forcing
1373a connect attempt. This allows you to configure its options
1374(like making it non-blocking) and then call connect() manually.
1375
1376A bug that prevented the IO::Socket::protocol() accessor
1377from ever returning the correct value has been corrected.
1378
1379=item JPL
1380
1381Java Perl Lingo is now distributed with Perl. See jpl/README
1382for more information.
1383
883d36a6
GS
1384=item lib
1385
1386C<use lib> now weeds out any trailing duplicate entries.
1387C<no lib> removes all named entries.
1388
e16b8f49
WM
1389=item Math::BigInt
1390
437784d6 1391The bitwise operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, C<&>, C<|>,
e16b8f49
WM
1392and C<~> are now supported on bigints.
1393
b7d8191e 1394=item Math::Complex
7711098a 1395
14218588 1396The accessor methods Re, Im, arg, abs, rho, and theta can now also
868cb350 1397act as mutators (accessor $z->Re(), mutator $z->Re(3)).
b7d8191e
JH
1398
1399=item Math::Trig
1400
14218588
GS
1401A little bit of radial trigonometry (cylindrical and spherical),
1402radial coordinate conversions, and the great circle distance were added.
b7d8191e 1403
a5222a85
GS
1404=item Pod::Parser
1405
1406[TODO - Brad Appleton <bradapp@enteract.com>]
1407
1408=item Pod::Text and Pod::Man
1409
1410[TODO - Russ Allbery <rra@stanford.edu>]
1411
f4b9d880
RA
1412=item SDBM_File
1413
1414An EXISTS method has been added to this module (and sdbm_exists() has
1415been added to the underlying sdbm library), so one can now call exists
14218588 1416on an SDBM_File tied hash and get the correct result, rather than a
f4b9d880
RA
1417runtime error.
1418
a5222a85
GS
1419A bug that may have caused data loss when more than one disk block
1420happens to be read from the database in a single FETCH() has been
1421fixed.
1422
06ef4121
PC
1423=item Time::Local
1424
1425The timelocal() and timegm() functions used to silently return bogus
437784d6 1426results when the date fell outside the machine's integer range. They
a5222a85 1427now consistently croak() if the date falls in an unsupported range.
06ef4121 1428
8fe0a5c4
JD
1429=item Win32
1430
1431The error return value in list context has been changed for all functions
14218588
GS
1432that return a list of values. Previously these functions returned a list
1433with a single element C<undef> if an error occurred. Now these functions
1434return the empty list in these situations. This applies to the following
8fe0a5c4
JD
1435functions:
1436
14218588
GS
1437 Win32::FsType
1438 Win32::GetOSVersion
8fe0a5c4
JD
1439
1440The remaining functions are unchanged and continue to return C<undef> on
1441error even in list context.
1442
1443The Win32::SetLastError(ERROR) function has been added as a complement
1444to the Win32::GetLastError() function.
1445
1446The new Win32::GetFullPathName(FILENAME) returns the full absolute
14218588
GS
1447pathname for FILENAME in scalar context. In list context it returns
1448a two-element list containing the fully qualified directory name and
501fbaef 1449the filename. See L<Win32>.
8fe0a5c4 1450
9fe6733a
PM
1451=item DBM Filters
1452
1453A new feature called "DBM Filters" has been added to all the
14218588
GS
1454DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File.
1455DBM Filters add four new methods to each DBM module:
9fe6733a
PM
1456
1457 filter_store_key
1458 filter_store_value
1459 filter_fetch_key
1460 filter_fetch_value
1461
14218588 1462These can be used to filter key-value pairs before the pairs are
9fe6733a
PM
1463written to the database or just after they are read from the database.
1464See L<perldbmfilter> for further information.
1465
b7d8191e 1466=back
3e8c4fa0
JH
1467
1468=head2 Pragmata
1469
437784d6 1470C<use attrs> is now obsolete, and is only provided for
09bef843
SB
1471backward-compatibility. It's been replaced by the C<sub : attributes>
1472syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>.
1473
14218588 1474C<use utf8> to enable UTF-8 and Unicode support.
43165c05
GS
1475
1476C<use caller 'encoding'> allows modules to inherit pragmatic attributes
1477from the caller's context. C<encoding> is currently the only supported
1478attribute.
9d73390d 1479
4438c4b7 1480Lexical warnings pragma, C<use warnings;>, to control optional warnings.
a5222a85 1481See L<perllexwarn>.
6c67e1bb 1482
67d3893f
JH
1483C<use filetest> to control the behaviour of filetests (C<-r> C<-w>
1484...). Currently only one subpragma implemented, "use filetest
1485'access';", that uses access(2) or equivalent to check permissions
1486instead of using stat(2) as usual. This matters in filesystems
1487where there are ACLs (access control lists): the stat(2) might lie,
1488but access(2) knows better.
6c67e1bb 1489
ba8251e8
GS
1490=head1 Utility Changes
1491
a5222a85
GS
1492=head2 h2ph
1493
1494[TODO - Kurt Starsinic <kstar@chapin.edu>]
1495
1496=head2 perlcc
1497
1498C<perlcc> now supports the C and Bytecode backends. By default,
1499it generates output from the simple C backend rather than the
1500optimized C backend.
1501
1502Support for non-Unix platforms has been improved.
1503
1504=head2 h2xs
1505
1506change#4232
1507[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
e02fdbd2 1508
ba8251e8
GS
1509=head1 Documentation Changes
1510
5fdc711f
GS
1511=over 4
1512
883d36a6
GS
1513=item perlcompile.pod
1514
1515An introduction to using the Perl Compiler suite.
1516
c7c04614
GS
1517=item perlfilter.pod
1518
1519An introduction to writing Perl source filters.
1520
883d36a6
GS
1521=item perlhack.pod
1522
1523Some guidelines for hacking the Perl source code.
1524
5fdc711f 1525=item perlopentut.pod
f8284313 1526
5fdc711f
GS
1527A tutorial on using open() effectively.
1528
1529=item perlreftut.pod
1530
1531A tutorial that introduces the essentials of references.
1532
14218588
GS
1533=item perltootc.pod
1534
1535A tutorial on managing class data for object modules.
1536
5fdc711f 1537=back
e02fdbd2 1538
73b437c8 1539=head1 New or Changed Diagnostics
ba8251e8 1540
a99ba403
GS
1541=over 4
1542
09bef843
SB
1543=item "my sub" not yet implemented
1544
1545(F) Lexically scoped subroutines are not yet implemented. Don't try that
1546yet.
1547
a99ba403
GS
1548=item '!' allowed only after types %s
1549
1550(F) The '!' is allowed in pack() and unpack() only after certain types.
1551See L<perlfunc/pack>.
1552
1553=item / cannot take a count
1554
1555(F) You had an unpack template indicating a counted-length string,
1556but you have also specified an explicit size for the string.
1557See L<perlfunc/pack>.
1558
1559=item / must be followed by a, A or Z
1560
1561(F) You had an unpack template indicating a counted-length string,
1562which must be followed by one of the letters a, A or Z
1563to indicate what sort of string is to be unpacked.
1564See L<perlfunc/pack>.
1565
1566=item / must be followed by a*, A* or Z*
1567
437784d6 1568(F) You had a pack template indicating a counted-length string,
a99ba403
GS
1569Currently the only things that can have their length counted are a*, A* or Z*.
1570See L<perlfunc/pack>.
1571
1572=item / must follow a numeric type
1573
1574(F) You had an unpack template that contained a '#',
1575but this did not follow some numeric unpack specification.
1576See L<perlfunc/pack>.
1577
a99ba403
GS
1578=item /%s/: Unrecognized escape \\%c passed through
1579
1580(W) You used a backslash-character combination which is not recognized
1581by Perl. This combination appears in an interpolated variable or a
1028017a
JH
1582C<'>-delimited regular expression. The character was understood literally.
1583
1584=item /%s/: Unrecognized escape \\%c in character class passed through
1585
1586(W) You used a backslash-character combination which is not recognized
1587by Perl inside character classes. The character was understood literally.
a99ba403
GS
1588
1589=item /%s/ should probably be written as "%s"
1590
1591(W) You have used a pattern where Perl expected to find a string,
437784d6 1592as in the first argument to C<join>. Perl will treat the true
a99ba403
GS
1593or false result of matching the pattern against $_ as the string,
1594which is probably not what you had in mind.
1595
1596=item %s() called too early to check prototype
1597
1598(W) You've called a function that has a prototype before the parser saw a
1599definition or declaration for it, and Perl could not check that the call
1600conforms to the prototype. You need to either add an early prototype
1601declaration for the subroutine in question, or move the subroutine
1602definition ahead of the call to get proper prototype checking. Alternatively,
1603if you are certain that you're calling the function correctly, you may put
1604an ampersand before the name to avoid the warning. See L<perlsub>.
1605
afebc493
GS
1606=item %s argument is not a subroutine name
1607
1608(F) The argument to exists() for C<exists &sub> must be a subroutine
1609name, and not a subroutine call. C<exists &sub()> will generate this error.
1610
09bef843
SB
1611=item %s package attribute may clash with future reserved word: %s
1612
1613(W) A lowercase attribute name was used that had a package-specific handler.
1614That name might have a meaning to Perl itself some day, even though it
1615doesn't yet. Perhaps you should use a mixed-case attribute name, instead.
1616See L<attributes>.
1617
a99ba403 1618=item (in cleanup) %s
6b121555 1619
a99ba403
GS
1620(W) This prefix usually indicates that a DESTROY() method raised
1621the indicated exception. Since destructors are usually called by
1622the system at arbitrary points during execution, and often a vast
1623number of times, the warning is issued only once for any number
1624of failures that would otherwise result in the same message being
1625repeated.
1626
1627Failure of user callbacks dispatched using the C<G_KEEPERR> flag
1628could also result in this warning. See L<perlcall/G_KEEPERR>.
1629
1630=item <> should be quotes
1631
1632(F) You wrote C<require E<lt>fileE<gt>> when you should have written
1633C<require 'file'>.
1634
1635=item Attempt to join self
1636
1637(F) You tried to join a thread from within itself, which is an
1638impossible task. You may be joining the wrong thread, or you may
1639need to move the join() to some other thread.
1640
1641=item Bad evalled substitution pattern
1642
1643(F) You've used the /e switch to evaluate the replacement for a
1644substitution, but perl found a syntax error in the code to evaluate,
1645most likely an unexpected right brace '}'.
1646
1647=item Bad realloc() ignored
1648
1649(S) An internal routine called realloc() on something that had never been
1650malloc()ed in the first place. Mandatory, but can be disabled by
1651setting environment variable C<PERL_BADFREE> to 1.
1652
1653=item Binary number > 0b11111111111111111111111111111111 non-portable
1654
1655(W) The binary number you specified is larger than 2**32-1
1656(4294967295) and therefore non-portable between systems. See
1657L<perlport> for more on portability concerns.
1658
1659=item Bit vector size > 32 non-portable
1660
1661(W) Using bit vector sizes larger than 32 is non-portable.
1662
1663=item Buffer overflow in prime_env_iter: %s
1664
1665(W) A warning peculiar to VMS. While Perl was preparing to iterate over
1666%ENV, it encountered a logical name or symbol definition which was too long,
1667so it was truncated to the string shown.
1668
1669=item Can't check filesystem of script "%s"
1670
1671(P) For some reason you can't check the filesystem of the script for nosuid.
1672
0b5b802d
GS
1673=item Can't ignore signal CHLD, forcing to default
1674
1675(W) Perl has detected that it is being run with the SIGCHLD signal
1676(sometimes known as SIGCLD) disabled. Since disabling this signal
1677will interfere with proper determination of exit status of child
1678processes, Perl has reset the signal to its default value.
1679This situation typically indicates that the parent program under
1680which Perl may be running (e.g. cron) is being very careless.
1681
a99ba403
GS
1682=item Can't modify non-lvalue subroutine call
1683
437784d6
GS
1684(F) Subroutines meant to be used in lvalue context should be declared as
1685such, see L<perlsub/"Lvalue subroutines">.
a99ba403
GS
1686
1687=item Can't read CRTL environ
1688
1689(S) A warning peculiar to VMS. Perl tried to read an element of %ENV
1690from the CRTL's internal environment array and discovered the array was
1691missing. You need to figure out where your CRTL misplaced its environ
1692or define F<PERL_ENV_TABLES> (see L<perlvms>) so that environ is not searched.
1693
1694=item Can't remove %s: %s, skipping file
1695
1696(S) You requested an inplace edit without creating a backup file. Perl
1697was unable to remove the original file to replace it with the modified
1698file. The file was left unmodified.
1699
1700=item Can't return %s from lvalue subroutine
1701
1702(F) Perl detected an attempt to return illegal lvalues (such
1703as temporary or readonly values) from a subroutine used as an lvalue.
1704This is not allowed.
1705
1706=item Can't weaken a nonreference
1707
1708(F) You attempted to weaken something that was not a reference. Only
1709references can be weakened.
1710
1711=item Character class [:%s:] unknown
1712
1713(F) The class in the character class [: :] syntax is unknown.
437784d6 1714See L<perlre>.
a99ba403
GS
1715
1716=item Character class syntax [%s] belongs inside character classes
1717
1718(W) The character class constructs [: :], [= =], and [. .] go
1719I<inside> character classes, the [] are part of the construct,
437784d6
GS
1720for example: /[012[:alpha:]345]/. Note that [= =] and [. .]
1721are not currently implemented; they are simply placeholders for
1722future extensions.
a99ba403
GS
1723
1724=item Constant is not %s reference
1725
1726(F) A constant value (perhaps declared using the C<use constant> pragma)
1727is being dereferenced, but it amounts to the wrong type of reference. The
1728message indicates the type of reference that was expected. This usually
1729indicates a syntax error in dereferencing the constant value.
1730See L<perlsub/"Constant Functions"> and L<constant>.
1731
1732=item constant(%s): %%^H is not localized
1733
1734(F) When setting compile-time-lexicalized hash %^H one should set the
1735corresponding bit of $^H as well.
1736
1737=item constant(%s): %s
1738
1739(F) Compile-time-substitutions (such as overloaded constants and
1740character names) were not correctly set up.
1741
1742=item defined(@array) is deprecated
1743
1744(D) defined() is not usually useful on arrays because it checks for an
1745undefined I<scalar> value. If you want to see if the array is empty,
1746just use C<if (@array) { # not empty }> for example.
1747
1748=item defined(%hash) is deprecated
1749
1750(D) defined() is not usually useful on hashes because it checks for an
1751undefined I<scalar> value. If you want to see if the hash is empty,
1752just use C<if (%hash) { # not empty }> for example.
1753
1754=item Did not produce a valid header
1755
1756See Server error.
1757
1758=item Document contains no data
1759
1760See Server error.
1761
1762=item entering effective %s failed
1763
1764(F) While under the C<use filetest> pragma, switching the real and
1765effective uids or gids failed.
6b121555 1766
73b437c8
JH
1767=item false [] range "%s" in regexp
1768
1769(W) A character class range must start and end at a literal character, not
1770another character class like C<\d> or C<[:alpha:]>. The "-" in your false
1771range is interpreted as a literal "-". Consider quoting the "-", "\-".
1772See L<perlre>.
1773
af8c498a 1774=item Filehandle %s opened only for output
6b121555 1775
af8c498a 1776(W) You tried to read from a filehandle opened only for writing. If you
437784d6 1777intended it to be a read/write filehandle, you needed to open it with
af8c498a
GS
1778"+E<lt>" or "+E<gt>" or "+E<gt>E<gt>" instead of with "E<lt>" or nothing. If
1779you intended only to read from the file, use "E<lt>". See
1780L<perlfunc/open>.
e02fdbd2 1781
a99ba403
GS
1782=item Hexadecimal number > 0xffffffff non-portable
1783
1784(W) The hexadecimal number you specified is larger than 2**32-1
1785(4294967295) and therefore non-portable between systems. See
1786L<perlport> for more on portability concerns.
1787
1788=item Ill-formed CRTL environ value "%s"
1789
1790(W) A warning peculiar to VMS. Perl tried to read the CRTL's internal
1791environ array, and encountered an element without the C<=> delimiter
1792used to spearate keys from values. The element is ignored.
1793
1794=item Ill-formed message in prime_env_iter: |%s|
1795
1796(W) A warning peculiar to VMS. Perl tried to read a logical name
1797or CLI symbol definition when preparing to iterate over %ENV, and
1798didn't see the expected delimiter between key and value, so the
1799line was ignored.
1800
1801=item Illegal binary digit %s
1802
437784d6 1803(F) You used a digit other than 0 or 1 in a binary number.
a99ba403
GS
1804
1805=item Illegal binary digit %s ignored
1806
1807(W) You may have tried to use a digit other than 0 or 1 in a binary number.
1808Interpretation of the binary number stopped before the offending digit.
1809
1810=item Illegal number of bits in vec
1811
1812(F) The number of bits in vec() (the third argument) must be a power of
1813two from 1 to 32 (or 64, if your platform supports that).
1814
1815=item Integer overflow in %s number
1816
1817(W) The hexadecimal, octal or binary number you have specified either
c6edd1b7 1818as a literal or as an argument to hex() or oct() is too big for your
a99ba403
GS
1819architecture, and has been converted to a floating point number. On a
182032-bit architecture the largest hexadecimal, octal or binary number
1821representable without overflow is 0xFFFFFFFF, 037777777777, or
18220b11111111111111111111111111111111 respectively. Note that Perl
1823transparently promotes all numbers to a floating point representation
1824internally--subject to loss of precision errors in subsequent
1825operations.
1826
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SB
1827=item Invalid %s attribute: %s
1828
1829The indicated attribute for a subroutine or variable was not recognized
1830by Perl or by a user-supplied handler. See L<attributes>.
1831
1832=item Invalid %s attributes: %s
1833
1834The indicated attributes for a subroutine or variable were not recognized
1835by Perl or by a user-supplied handler. See L<attributes>.
1836
73b437c8
JH
1837=item invalid [] range "%s" in regexp
1838
1839The offending range is now explicitly displayed.
1840
09bef843
SB
1841=item Invalid separator character %s in attribute list
1842
1843(F) Something other than a comma or whitespace was seen between the
1844elements of an attribute list. If the previous attribute
1845had a parenthesised parameter list, perhaps that list was terminated
1846too soon. See L<attributes>.
1847
a99ba403
GS
1848=item Invalid separator character %s in subroutine attribute list
1849
1850(F) Something other than a comma or whitespace was seen between the
1851elements of a subroutine attribute list. If the previous attribute
1852had a parenthesised parameter list, perhaps that list was terminated
1853too soon.
1854
1855=item leaving effective %s failed
1856
1857(F) While under the C<use filetest> pragma, switching the real and
1858effective uids or gids failed.
1859
1860=item Lvalue subs returning %s not implemented yet
1861
1862(F) Due to limitations in the current implementation, array and hash
1863values cannot be returned in subroutines used in lvalue context.
1864See L<perlsub/"Lvalue subroutines">.
1865
1866=item Method %s not permitted
1867
1868See Server error.
1869
1870=item Missing %sbrace%s on \N{}
1871
1872(F) Wrong syntax of character name literal C<\N{charname}> within
1873double-quotish context.
1874
06eaf0bc
GS
1875=item Missing command in piped open
1876
1877(W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
1878construction, but the command was missing or blank.
1879
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SB
1880=item Missing name in "my sub"
1881
1882(F) The reserved syntax for lexically scoped subroutines requires that they
1883have a name with which they can be found.
1884
a99ba403
GS
1885=item no UTC offset information; assuming local time is UTC
1886
1887(S) A warning peculiar to VMS. Perl was unable to find the local
1888timezone offset, so it's assuming that local system time is equivalent
1889to UTC. If it's not, define the logical name F<SYS$TIMEZONE_DIFFERENTIAL>
1890to translate to the number of seconds which need to be added to UTC to
1891get local time.
1892
1893=item Octal number > 037777777777 non-portable
1894
1895(W) The octal number you specified is larger than 2**32-1 (4294967295)
1896and therefore non-portable between systems. See L<perlport> for more
1897on portability concerns.
1898
1899See also L<perlport> for writing portable code.
1900
1901=item panic: del_backref
1902
1903(P) Failed an internal consistency check while trying to reset a weak
1904reference.
1905
1906=item panic: kid popen errno read
1907
1908(F) forked child returned an incomprehensible message about its errno.
1909
1910=item panic: magic_killbackrefs
1911
1912(P) Failed an internal consistency check while trying to reset all weak
1913references to an object.
1914
1915=item Possible Y2K bug: %s
1916
1917(W) You are concatenating the number 19 with another number, which
1918could be a potential Year 2000 problem.
1919
1920=item Premature end of script headers
1921
1922See Server error.
1923
0b5b802d
GS
1924=item Repeat count in pack overflows
1925
1926(F) You can't specify a repeat count so large that it overflows
1927your signed integers. See L<perlfunc/pack>.
1928
1929=item Repeat count in unpack overflows
1930
1931(F) You can't specify a repeat count so large that it overflows
1932your signed integers. See L<perlfunc/unpack>.
1933
a99ba403
GS
1934=item realloc() of freed memory ignored
1935
1936(S) An internal routine called realloc() on something that had already
1937been freed.
1938
1939=item Reference is already weak
1940
1941(W) You have attempted to weaken a reference that is already weak.
1942Doing so has no effect.
1943
1944=item setpgrp can't take arguments
1945
1946(F) Your system has the setpgrp() from BSD 4.2, which takes no arguments,
1947unlike POSIX setpgid(), which takes a process ID and process group ID.
1948
1949=item Strange *+?{} on zero-length expression
1950
1951(W) You applied a regular expression quantifier in a place where it
1952makes no sense, such as on a zero-width assertion.
1953Try putting the quantifier inside the assertion instead. For example,
1954the way to match "abc" provided that it is followed by three
1955repetitions of "xyz" is C</abc(?=(?:xyz){3})/>, not C</abc(?=xyz){3}/>.
1956
1957=item switching effective %s is not implemented
1958
1959(F) While under the C<use filetest> pragma, we cannot switch the
1960real and effective uids or gids.
1961
437784d6 1962=item This Perl can't reset CRTL environ elements (%s)
a99ba403
GS
1963
1964=item This Perl can't set CRTL environ elements (%s=%s)
1965
1966(W) Warnings peculiar to VMS. You tried to change or delete an element
1967of the CRTL's internal environ array, but your copy of Perl wasn't
1968built with a CRTL that contained the setenv() function. You'll need to
1969rebuild Perl with a CRTL that does, or redefine F<PERL_ENV_TABLES> (see
1970L<perlvms>) so that the environ array isn't the target of the change to
1971%ENV which produced the warning.
1972
1973=item Unknown open() mode '%s'
1974
437784d6
GS
1975(F) The second argument of 3-argument open() is not among the list
1976of valid modes: C<L<lt>>, C<L<gt>>, C<E<gt>E<gt>>, C<+L<lt>>,
1977C<+L<gt>>, C<+E<gt>E<gt>>, C<-|>, C<|->.
a99ba403
GS
1978
1979=item Unknown process %x sent message to prime_env_iter: %s
1980
1981(P) An error peculiar to VMS. Perl was reading values for %ENV before
1982iterating over it, and someone else stuck a message in the stream of
1983data Perl expected. Someone's very confused, or perhaps trying to
1984subvert Perl's population of %ENV for nefarious purposes.
1985
af8c498a
GS
1986=item Unrecognized escape \\%c passed through
1987
1988(W) You used a backslash-character combination which is not recognized
1028017a 1989by Perl. The character was understood literally.
af8c498a 1990
09bef843
SB
1991=item Unterminated attribute parameter in attribute list
1992
1993(F) The lexer saw an opening (left) parenthesis character while parsing an
1994attribute list, but the matching closing (right) parenthesis
1995character was not found. You may need to add (or remove) a backslash
1996character to get your parentheses to balance. See L<attributes>.
1997
1998=item Unterminated attribute list
1999
2000(F) The lexer found something other than a simple identifier at the start
2001of an attribute, and it wasn't a semicolon or the start of a
2002block. Perhaps you terminated the parameter list of the previous attribute
2003too soon. See L<attributes>.
2004
09bef843
SB
2005=item Unterminated attribute parameter in subroutine attribute list
2006
2007(F) The lexer saw an opening (left) parenthesis character while parsing a
2008subroutine attribute list, but the matching closing (right) parenthesis
2009character was not found. You may need to add (or remove) a backslash
2010character to get your parentheses to balance.
2011
2012=item Unterminated subroutine attribute list
2013
2014(F) The lexer found something other than a simple identifier at the start
2015of a subroutine attribute, and it wasn't a semicolon or the start of a
2016block. Perhaps you terminated the parameter list of the previous attribute
2017too soon.
2018
a99ba403 2019=item Value of CLI symbol "%s" too long
eb6e2d6f 2020
a99ba403
GS
2021(W) A warning peculiar to VMS. Perl tried to read the value of an %ENV
2022element from a CLI symbol table, and found a resultant string longer
2023than 1024 characters. The return value has been truncated to 1024
2024characters.
eb6e2d6f 2025
a99ba403 2026=item Version number must be a constant number
ba8251e8 2027
a99ba403
GS
2028(P) The attempt to translate a C<use Module n.n LIST> statement into
2029its equivalent C<BEGIN> block found an internal inconsistency with
2030the version number.
2031
2032=back
27806c82 2033
a5222a85 2034=head1 Obsolete Diagnostics
3175b8cd 2035
a99ba403
GS
2036=over 4
2037
2038=item Character class syntax [: :] is reserved for future extensions
2039
2040(W) Within regular expression character classes ([]) the syntax beginning
2041with "[:" and ending with ":]" is reserved for future extensions.
2042If you need to represent those character sequences inside a regular
2043expression character class, just quote the square brackets with the
2044backslash: "\[:" and ":\]".
2045
2046=item Ill-formed logical name |%s| in prime_env_iter
2047
2048(W) A warning peculiar to VMS. A logical name was encountered when preparing
2049to iterate over %ENV which violates the syntactic rules governing logical
2050names. Because it cannot be translated normally, it is skipped, and will not
2051appear in %ENV. This may be a benign occurrence, as some software packages
2052might directly modify logical name tables and introduce nonstandard names,
2053or it may indicate that a logical name table has been corrupted.
2054
2055=item regexp too big
2056
2057(F) The current implementation of regular expressions uses shorts as
2058address offsets within a string. Unfortunately this means that if
2059the regular expression compiles to longer than 32767, it'll blow up.
2060Usually when you want a regular expression this big, there is a better
2061way to do it with multiple statements. See L<perlre>.
2062
2063=item Use of "$$<digit>" to mean "${$}<digit>" is deprecated
2064
2065(D) Perl versions before 5.004 misinterpreted any type marker followed
2066by "$" and a digit. For example, "$$0" was incorrectly taken to mean
2067"${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004.
2068
2069However, the developers of Perl 5.004 could not fix this bug completely,
2070because at least two widely-used modules depend on the old meaning of
2071"$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the
2072old (broken) way inside strings; but it generates this message as a
2073warning. And in Perl 5.005, this special treatment will cease.
2074
2075=back
3175b8cd 2076
ba8251e8
GS
2077=head1 BUGS
2078
437784d6 2079If you find what you think is a bug, you might check the
14218588 2080articles recently posted to the comp.lang.perl.misc newsgroup.
ba8251e8
GS
2081There may also be information at http://www.perl.com/perl/, the Perl
2082Home Page.
2083
2084If you believe you have an unreported bug, please run the B<perlbug>
14218588 2085program included with your release. Make sure to trim your bug down
ba8251e8 2086to a tiny but sufficient test case. Your bug report, along with the
14218588 2087output of C<perl -V>, will be sent off to perlbug@perl.com to be
ba8251e8
GS
2088analysed by the Perl porting team.
2089
2090=head1 SEE ALSO
2091
2092The F<Changes> file for exhaustive details on what changed.
2093
2094The F<INSTALL> file for how to build Perl.
2095
2096The F<README> file for general stuff.
2097
2098The F<Artistic> and F<Copying> files for copyright information.
2099
2100=head1 HISTORY
2101
a5222a85
GS
2102Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many
2103contributions from The Perl Porters.
ba8251e8
GS
2104
2105Send omissions or corrections to <F<perlbug@perl.com>>.
2106
2107=cut