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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
191f2cf3 734With C<$/> set to C<undef>, "slurping" an empty file returns a string of
14218588 735zero length (instead of C<undef>, as it used to) the first time the
191f2cf3
GS
736HANDLE is read after C<$/> is set to C<undef>. Further reads yield
737C<undef>.
fbad3eb5
GS
738
739This means that the following will append "foo" to an empty file (it used
14218588 740to do nothing):
fbad3eb5
GS
741
742 perl -0777 -pi -e 's/^/foo/' empty_file
743
14218588 744The behaviour of:
fbad3eb5
GS
745
746 perl -pi -e 's/^/foo/' empty_file
747
748is unchanged (it continues to leave the file empty).
749
0244c3a4
GS
750=head2 C<eval '...'> improvements
751
752Line numbers (as reflected by caller() and most diagnostics) within
753C<eval '...'> were often incorrect when here documents were involved.
754This has been corrected.
755
756Lexical lookups for variables appearing in C<eval '...'> within
757functions that were themselves called within an C<eval '...'> were
14218588
GS
758searching the wrong place for lexicals. The lexical search now
759correctly ends at the subroutine's block boundary.
0244c3a4
GS
760
761Parsing of here documents used to be flawed when they appeared as
762the replacement expression in C<eval 's/.../.../e'>. This has
763been fixed.
764
a5222a85
GS
765=head2 All compilation errors are true errors
766
767Some "errors" encountered at compile time were by neccessity
768generated as warnings followed by eventual termination of the
769program. This enabled more such errors to be reported in a
770single run, rather than causing a hard stop at the first error
771that was encountered.
772
773The mechanism for reporting such errors has been reimplemented
774to queue compile-time errors and report them at the end of the
775compilation as true errors rather than as warnings. This fixes
08cd8952
GS
776cases where error messages leaked through in the form of warnings
777when code was compiled at run time using C<eval STRING>, and
778also allows such errors to be reliably trapped using __DIE__ hooks.
a5222a85 779
45bc9206
GS
780=head2 Automatic flushing of output buffers
781
14218588
GS
782fork(), exec(), system(), qx//, and pipe open()s now flush buffers
783of all files opened for output when the operation
784was attempted. This mostly eliminates confusing
45bc9206 785buffering mishaps suffered by users unaware of how Perl internally
14218588 786handles I/O.
45bc9206 787
af8c498a
GS
788=head2 Better diagnostics on meaningless filehandle operations
789
790Constructs such as C<open(E<lt>FHE<gt>)> and C<close(E<lt>FHE<gt>)>
791are compile time errors. Attempting to read from filehandles that
792were opened only for writing will now produce warnings (just as
793writing to read-only filehandles does).
794
a5222a85
GS
795=head2 Where possible, buffered data discarded from duped input filehandle
796
797C<open(NEW, "E<lt>&OLD")> now attempts to discard any data that
798was previously read and buffered in C<OLD> before duping the handle.
799On platforms where doing this is allowed, the next read operation
800on C<NEW> will return the same data as the corresponding operation
801on C<OLD>. Formerly, it would have returned the data from the start
802of the following disk block instead.
803
820475bd
GS
804=head2 eof() has the same old magic as <>
805
806C<eof()> would return true if no attempt to read from C<E<lt>E<gt>> had
807yet been made. C<eof()> has been changed to have a little magic of its
808own, it now opens the C<E<lt>E<gt>> files.
809
a5222a85
GS
810=head2 system(), backticks and pipe open now reflect exec() failure
811
812On Unix and similar platforms, system(), qx() and open(FOO, "cmd |")
813etc., are implemented via fork() and exec(). When the underlying
814exec() fails, earlier versions did not report the error properly,
815since the exec() happened to be in a different process.
816
817The child process now communicates with the parent about the
437784d6 818error in launching the external command, which allows these
a5222a85
GS
819constructs to return with their usual error value and set $!.
820
821=head2 Implicitly closed filehandles are safer
822
823Sometimes implicitly closed filehandles (as when they are localized,
824and Perl automatically closes them on exiting the scope) could
825inadvertently set $? or $!. This has been corrected.
826
827=head2 C<(\$)> prototype and C<$foo{a}>
828
829An scalar reference prototype now correctly allows a hash or
830array element in that slot.
831
832=head2 Pseudo-hashes work better
833
834Dereferencing some types of reference values in a pseudo-hash,
835such as C<$ph->{foo}[1]>, was accidentally disallowed. This has
836been corrected.
837
838When applied to a pseudo-hash element, exists() now reports whether
839the specified value exists, not merely if the key is valid.
840
01020589
GS
841delete() now works on pseudo-hashes. When given a pseudo-hash element
842or slice it deletes the values corresponding to the keys (but not the keys
843themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">.
844
a5222a85
GS
845=head2 C<goto &sub> and AUTOLOAD
846
08cd8952 847The C<goto &sub> construct works correctly when C<&sub> happens
a5222a85
GS
848to be autoloaded.
849
850=head2 C<-bareword> allowed under C<use integer>
851
852The autoquoting of barewords preceded by C<-> did not work
853in prior versions when the C<integer> pragma was enabled.
854This has been fixed.
855
856=head2 Boolean assignment operators are legal lvalues
857
858Constructs such as C<($a ||= 2) += 1> are now allowed.
859
860=head2 C<sort $coderef @foo> allowed
861
862sort() did not accept a subroutine reference as the comparison
08cd8952 863function in earlier versions. This is now permitted.
a5222a85
GS
864
865=head2 Failures in DESTROY()
866
867When code in a destructor threw an exception, it went unnoticed
868in earlier versions of Perl, unless someone happened to be
869looking in $@ just after the point the destructor happened to
870run. Such failures are now visible as warnings when warnings are
871enabled.
872
873=head2 Locale bugs fixed
54195c32 874
437784d6 875printf() and sprintf() previously reset the numeric locale
67d3893f
JH
876back to the default "C" locale. This has been fixed.
877
878Numbers formatted according to the local numeric locale
879(such as using a decimal comma instead of a decimal dot) caused
880"isn't numeric" warnings, even while the operations accessing
881those numbers produced correct results. The warnings are gone.
54195c32 882
a5222a85
GS
883=head2 Memory leaks
884
885The C<eval 'return sub {...}'> construct could sometimes leak
886memory. This has been fixed.
887
888Operations that aren't filehandle constructors used to leak memory
889when used on invalid filehandles. This has been fixed.
890
891Constructs that modified C<@_> could fail to deallocate values
892in C<@_> and thus leak memory. This has been corrected.
893
894=head2 Spurious subroutine stubs after failed subroutine calls
895
896Perl could sometimes create empty subroutine stubs when a
897subroutine was not found in the package. Such cases stopped
898later method lookups from progressing into base packages.
899This has been corrected.
900
901=head2 Consistent numeric conversions
902
903change#3378,3318
904[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
905
906=head2 Taint failures under C<-U>
907
908When running in unsafe mode, taint violations could sometimes
909cause silent failures. This has been fixed.
910
911=head2 END blocks and the C<-c> switch
912
913Prior versions used to run BEGIN B<and> END blocks when Perl was
914run in compile-only mode. Since this is typically not the expected
08cd8952 915behavior, END blocks are not executed anymore when the C<-c> switch
a5222a85
GS
916is used.
917
4f25aa18 918See L<STOP blocks> for how to run things when the compile phase ends.
a5222a85
GS
919
920=head2 Potential to leak DATA filehandles
921
922Using the C<__DATA__> token creates an implicit filehandle to
923the file that contains the token. It is the program's
924responsibility to close it when it is done reading from it.
925
926This caveat is now better explained in the documentation.
927See L<perldata>.
928
929=head2 Diagnostics follow STDERR
930
931Diagnostic output now goes to whichever file the C<STDERR> handle
932is pointing at, instead of always going to the underlying C runtime
933library's C<stderr>.
934
935=head2 Other fixes for better diagnostics
936
437784d6 937Line numbers are no longer suppressed (under most likely circumstances)
a5222a85
GS
938during the global destruction phase.
939
940Diagnostics emitted from code running in threads other than the main
941thread are now accompanied by the thread ID.
942
943Embedded null characters in diagnostics now actually show up. They
944used to truncate the message in prior versions.
945
946$foo::a and $foo::b are now exempt from "possible typo" warnings only
947if sort() is encountered in package foo.
948
501fbaef 949Unrecognized alphabetic escapes encountered when parsing quote
a5222a85
GS
950constructs now generate a warning, since they may take on new
951semantics in later versions of Perl.
952
953=head1 Performance enhancements
954
955=head2 Simple sort() using { $a <=> $b } and the like are optimized
956
08cd8952 957Many common sort() operations using a simple inlined block are now
a5222a85
GS
958optimized for faster performance.
959
960=head2 Optimized assignments to lexical variables
961
962Certain operations in the RHS of assignment statements have been
963optimized to directly set the lexical variable on the LHS,
964eliminating redundant copying overheads.
965
966=head2 Method lookups optimized
967
968[TODO - Chip Salzenberg <chip@perlsupport.com>]
969
970=head2 Faster mechanism to invoke XSUBs
971
972change#4044,4125
973[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
974
975=head2 Perl_malloc() improvements
976
977change#4237
978[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
979
980=head2 Faster subroutine calls
981
982Minor changes in how subroutine calls are handled internally
983provide marginal improvements in performance.
984
985=head1 Platform specific changes
986
987=head2 Additional supported platforms
ba8251e8 988
5fdc711f
GS
989=over 4
990
991=item *
992
6c67e1bb
TC
993VM/ESA is now supported.
994
5fdc711f
GS
995=item *
996
ee3907e2
JH
997Siemens BS2000 is now supported under the POSIX Shell.
998
999=item *
1000
2bb14304
JH
1001The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread
1002extension.
6c67e1bb 1003
5fdc711f
GS
1004=item *
1005
ee3907e2 1006GNU/Hurd is now supported.
6c67e1bb 1007
00ad96e1
JH
1008=item *
1009
1010Rhapsody is now supported.
1011
27806c82
JH
1012=item *
1013
1014EPOC is is now supported (on Psion 5).
1015
5fdc711f
GS
1016=back
1017
a5222a85
GS
1018=head2 DOS
1019
d524f05e
LM
1020=over 4
1021
1022=item *
1023
1024Perl now works with djgpp 2.02 (and 2.03 alpha).
1025
1026=item *
1027
1028Environment variable names are not converted to uppercase any more.
1029
1030=item *
1031
1032Wrong exit code from backticks now fixed.
1033
1034=item *
1035
1036This port is still using its own builtin globbing.
1037
1038=back
a5222a85
GS
1039
1040=head2 OS/2
1041
1042[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
1043
1044=head2 VMS
1045
1046[TODO - Charles Bailey <bailey@newman.upenn.edu>]
1047
1048=head2 Win32
1049
1050Site library searches failed to look for ".../site/5.XXX/lib"
1051if ".../site/5.XXXYY/lib" wasn't found. This has been corrected.
1052
1053When given a pathname that consists only of a drivename, such
1054as C<A:>, opendir() and stat() now use the current working
1055directory for the drive rather than the drive root.
1056
1057The builtin XSUB functions in the Win32:: namespace are
1058documented. See L<Win32>.
1059
1060$^X now contains the full path name of the running executable.
1061
1062A Win32::GetLongPathName() function is provided to complement
1063Win32::GetFullPathName() and Win32::GetShortPathName(). See L<Win32>.
1064
1065POSIX::uname() is supported.
1066
1067system(1,...) now returns true process IDs rather than process
1068handles. kill() accepts any real process id, rather than strictly
1069return values from system(1,...).
1070
1071The C<Shell> module is supported.
1072
883d36a6
GS
1073Rudimentary support for building under command.com in Windows 95
1074has been added.
1075
c39cd008
GS
1076Scripts are read in binary mode by default to allow ByteLoader (and
1077the filter mechanism in general) to work properly. For compatibility,
53129d29
GS
1078the DATA filehandle will be set to text mode if a carriage return is
1079detected at the end of the line containing the __END__ or __DATA__
1080token; if not, the DATA filehandle will be left open in binary mode.
1081Earlier versions always opened the DATA filehandle in text mode.
c39cd008 1082
a5222a85
GS
1083[TODO - GSAR]
1084
6c67e1bb
TC
1085=head1 New tests
1086
1087=over 4
1088
09bef843
SB
1089=item lib/attrs
1090
1091Compatibility tests for C<sub : attrs> vs the older C<use attrs>.
1092
1093=item lib/io_const
6c67e1bb
TC
1094
1095IO constants (SEEK_*, _IO*).
14218588 1096
09bef843 1097=item lib/io_dir
6c67e1bb
TC
1098
1099Directory-related IO methods (new, read, close, rewind, tied delete).
1100
09bef843 1101=item lib/io_multihomed
6c67e1bb
TC
1102
1103INET sockets with multi-homed hosts.
1104
09bef843 1105=item lib/io_poll
6c67e1bb
TC
1106
1107IO poll().
1108
09bef843 1109=item lib/io_unix
6c67e1bb
TC
1110
1111UNIX sockets.
1112
09bef843
SB
1113=item op/attrs
1114
1115Regression tests for C<my ($x,@y,%z) : attrs> and <sub : attrs>.
1116
6c67e1bb
TC
1117=item op/filetest
1118
1119File test operators.
1120
1121=item op/lex_assign
1122
5fdc711f 1123Verify operations that access pad objects (lexicals and temporaries).
6c67e1bb 1124
afebc493
GS
1125=item op/exists_sub
1126
1127Verify C<exists &sub> operations.
1128
6c67e1bb 1129=back
e02fdbd2 1130
ba8251e8
GS
1131=head1 Modules and Pragmata
1132
3e8c4fa0
JH
1133=head2 Modules
1134
b7d8191e
JH
1135=over 4
1136
09bef843
SB
1137=item attributes
1138
1139While used internally by Perl as a pragma, this module also
1140provides a way to fetch subroutine and variable attributes.
1141See L<attributes>.
1142
a5222a85
GS
1143=item B
1144
501fbaef
GS
1145The Perl Compiler suite has been extensively reworked for this
1146release.
1147
a5222a85
GS
1148[TODO - Vishal Bhatia <vishal@gol.com>,
1149Nick Ing-Simmons <nick@ni-s.u-net.com>]
1150
f29c64d6
GS
1151=item ByteLoader
1152
a5222a85 1153The ByteLoader is a dedicated extension to generate and run
f29c64d6
GS
1154Perl bytecode. See L<ByteLoader>.
1155
a5222a85
GS
1156=item constant
1157
83763826
GS
1158References can now be used.
1159
1160The new version also allows a leading underscore in constant names, but
1161disallows a double leading underscore (as in "__LINE__"). Some other names
1162are disallowed or warned against, including BEGIN, END, etc. Some names
1163which were forced into main:: used to fail silently in some cases; now they're
1164fatal (outside of main::) and an optional warning (inside of main::).
1165The ability to detect whether a constant had been set with a given name has
1166been added.
1167
1168See L<constant>.
a5222a85
GS
1169
1170=item charnames
1171
1172change#4052
1173[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
1174
1175=item Data::Dumper
1176
1177A C<Maxdepth> setting can be specified to avoid venturing
73b437c8 1178too deeply into deep data structures. See L<Data::Dumper>.
a5222a85
GS
1179
1180Dumping C<qr//> objects works correctly.
1181
1182=item DB
1183
1184C<DB> is an experimental module that exposes a clean abstraction
1185to Perl's debugging API.
1186
1187=item DB_File
1188
0536e0eb
GS
1189DB_File can now be built with Berkeley DB versions 1, 2 or 3.
1190See C<ext/DB_File/Changes>.
a5222a85 1191
f29c64d6
GS
1192=item Devel::DProf
1193
9e107c59
GS
1194Devel::DProf, a Perl source code profiler has been added. See
1195L<Devel::DProf> and L<dprofpp>.
f29c64d6 1196
b7d8191e
JH
1197=item Dumpvalue
1198
437784d6 1199The Dumpvalue module provides screen dumps of Perl data.
b7d8191e
JH
1200
1201=item Benchmark
1202
54e82ce5
GS
1203Overall, Benchmark results exhibit lower average error and better timing
1204accuracy.
1205
868cb350 1206You can now run tests for I<n> seconds instead of guessing the right
14218588
GS
1207number of tests to run: e.g. timethese(-5, ...) will run each
1208code for at least 5 CPU seconds. Zero as the "number of repetitions"
155776c0 1209means "for at least 3 CPU seconds". The output format has also
14218588 1210changed. For example:
155776c0 1211
54e82ce5 1212 use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
155776c0
JH
1213
1214will now output something like this:
1215
54e82ce5
GS
1216 Benchmark: running a, b, each for at least 5 CPU seconds...
1217 a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516)
1218 b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
155776c0
JH
1219
1220New features: "each for at least N CPU seconds...", "wallclock secs",
1221and the "@ operations/CPU second (n=operations)".
b7d8191e 1222
54e82ce5
GS
1223timethese() now returns a reference to a hash of Benchmark objects containing
1224the test results, keyed on the names of the tests.
1225
1226timethis() now returns the iterations field in the Benchmark result object
1227instead of 0.
1228
1229timethese(), timethis(), and the new cmpthese() (see below) can also take
1230a format specifier of 'none' to suppress output.
1231
1232A new function countit() is just like timeit() except that it takes a
1233TIME instead of a COUNT.
1234
1235A new function cmpthese() prints a chart comparing the results of each test
1236returned from a timethese() call. For each possible pair of tests, the
1237percentage speed difference (iters/sec or seconds/iter) is shown.
1238
1239For other details, see L<Benchmark>.
a5222a85 1240
f505c983
GS
1241=item Devel::Peek
1242
1243The Devel::Peek module provides access to the internal representation
14218588 1244of Perl variables and data. It is a data debugging tool for the XS programmer.
f505c983 1245
a5222a85
GS
1246=item ExtUtils::MakeMaker
1247
1248change#4135, also needs docs in module pod
1249[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
1250
b7d8191e
JH
1251=item Fcntl
1252
1253More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
14218588 1254large (more than 4G) file access (64-bit support is not yet
b7d8191e
JH
1255working, though, so no need to get overly excited), Free/Net/OpenBSD
1256locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
1257O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
1258
a5222a85
GS
1259=item File::Compare
1260
1261A compare_text() function has been added, which allows custom
1262comparison functions. See L<File::Compare>.
1263
1264=item File::Find
1265
1266File::Find now works correctly when the wanted() function is either
1267autoloaded or is a symbolic reference.
1268
08cd8952 1269A bug that caused File::Find to lose track of the working directory
a5222a85
GS
1270when pruning top-level directories has been fixed.
1271
81793b90
GS
1272File::Find now also supports several other options to control its
1273behavior. It can follow symbolic links if the C<follow> option is
1274specified. Enabling the C<no_chdir> option will make File::Find skip
1275changing the current directory when walking directories. The C<untaint>
1276flag can be useful when running with taint checks enabled.
1277
1278See L<File::Find>.
1279
becf2bd3
GS
1280=item File::Glob
1281
52bb0670
GS
1282This extension implements BSD-style file globbing. By default,
1283it will also be used for the internal implementation of the glob()
1284operator. See L<File::Glob>.
becf2bd3 1285
f505c983
GS
1286=item File::Spec
1287
1288New methods have been added to the File::Spec module: devnull() returns
19799a22 1289the name of the null device (/dev/null on Unix) and tmpdir() the name of
14218588 1290the temp directory (normally /tmp on Unix). There are now also methods
f505c983 1291to convert between absolute and relative filenames: abs2rel() and
14218588
GS
1292rel2abs(). For compatibility with operating systems that specify volume
1293names in file paths, the splitpath(), splitdir(), and catdir() methods
f505c983
GS
1294have been added.
1295
1296=item File::Spec::Functions
1297
1298The new File::Spec::Functions modules provides a function interface
14218588 1299to the File::Spec module. Allows shorthand
f505c983 1300
14218588 1301 $fullname = catfile($dir1, $dir2, $file);
f505c983
GS
1302
1303instead of
1304
14218588 1305 $fullname = File::Spec->catfile($dir1, $dir2, $file);
f505c983 1306
a5222a85
GS
1307=item Getopt::Long
1308
c6edd1b7
GS
1309Getopt::Long licensing has changed to allow the Perl Artistic License
1310as well as the GPL. It used to be GPL only, which got in the way of
1311non-GPL applications that wanted to use Getopt::Long.
1312
1313Getopt::Long encourages the use of Pod::Usage to produce help
1314messages. For example:
1315
1316 use Getopt::Long;
1317 use Pod::Usage;
1318 my $man = 0;
1319 my $help = 0;
1320 GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
1321 pod2usage(1) if $help;
1322 pod2usage(-exitstatus => 0, -verbose => 2) if $man;
1323
1324 __END__
1325
1326 =head1 NAME
1327
1328 sample - Using GetOpt::Long and Pod::Usage
1329
1330 =head1 SYNOPSIS
1331
1332 sample [options] [file ...]
1333
1334 Options:
1335 -help brief help message
1336 -man full documentation
1337
1338 =head1 OPTIONS
1339
1340 =over 8
1341
1342 =item B<-help>
1343
1344 Print a brief help message and exits.
1345
1346 =item B<-man>
1347
1348 Prints the manual page and exits.
1349
1350 =back
1351
1352 =head1 DESCRIPTION
1353
1354 B<This program> will read the given input file(s) and do someting
1355 useful with the contents thereof.
1356
1357 =cut
1358
1359See L<Pod::Usage> for details.
1360
1361A bug that prevented the non-option call-back E<lt>E<gt> from being
1362specified as the first argument has been fixed.
1363
1364To specify the characters E<lt> and E<gt> as option starters, use
1365E<gt>E<lt>. Note, however, that changing option starters is strongly
1366deprecated.
a5222a85
GS
1367
1368=item IO
1369
1370write() and syswrite() will now accept a single-argument
1371form of the call, for consistency with Perl's syswrite().
1372
1373You can now create a TCP-based IO::Socket::INET without forcing
1374a connect attempt. This allows you to configure its options
1375(like making it non-blocking) and then call connect() manually.
1376
1377A bug that prevented the IO::Socket::protocol() accessor
1378from ever returning the correct value has been corrected.
1379
1380=item JPL
1381
1382Java Perl Lingo is now distributed with Perl. See jpl/README
1383for more information.
1384
883d36a6
GS
1385=item lib
1386
1387C<use lib> now weeds out any trailing duplicate entries.
1388C<no lib> removes all named entries.
1389
e16b8f49
WM
1390=item Math::BigInt
1391
437784d6 1392The bitwise operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, C<&>, C<|>,
e16b8f49
WM
1393and C<~> are now supported on bigints.
1394
b7d8191e 1395=item Math::Complex
7711098a 1396
14218588 1397The accessor methods Re, Im, arg, abs, rho, and theta can now also
868cb350 1398act as mutators (accessor $z->Re(), mutator $z->Re(3)).
b7d8191e
JH
1399
1400=item Math::Trig
1401
14218588
GS
1402A little bit of radial trigonometry (cylindrical and spherical),
1403radial coordinate conversions, and the great circle distance were added.
b7d8191e 1404
a5222a85
GS
1405=item Pod::Parser
1406
1407[TODO - Brad Appleton <bradapp@enteract.com>]
1408
1409=item Pod::Text and Pod::Man
1410
1411[TODO - Russ Allbery <rra@stanford.edu>]
1412
f4b9d880
RA
1413=item SDBM_File
1414
1415An EXISTS method has been added to this module (and sdbm_exists() has
1416been added to the underlying sdbm library), so one can now call exists
14218588 1417on an SDBM_File tied hash and get the correct result, rather than a
f4b9d880
RA
1418runtime error.
1419
a5222a85
GS
1420A bug that may have caused data loss when more than one disk block
1421happens to be read from the database in a single FETCH() has been
1422fixed.
1423
06ef4121
PC
1424=item Time::Local
1425
1426The timelocal() and timegm() functions used to silently return bogus
437784d6 1427results when the date fell outside the machine's integer range. They
a5222a85 1428now consistently croak() if the date falls in an unsupported range.
06ef4121 1429
8fe0a5c4
JD
1430=item Win32
1431
1432The error return value in list context has been changed for all functions
14218588
GS
1433that return a list of values. Previously these functions returned a list
1434with a single element C<undef> if an error occurred. Now these functions
1435return the empty list in these situations. This applies to the following
8fe0a5c4
JD
1436functions:
1437
14218588
GS
1438 Win32::FsType
1439 Win32::GetOSVersion
8fe0a5c4
JD
1440
1441The remaining functions are unchanged and continue to return C<undef> on
1442error even in list context.
1443
1444The Win32::SetLastError(ERROR) function has been added as a complement
1445to the Win32::GetLastError() function.
1446
1447The new Win32::GetFullPathName(FILENAME) returns the full absolute
14218588
GS
1448pathname for FILENAME in scalar context. In list context it returns
1449a two-element list containing the fully qualified directory name and
501fbaef 1450the filename. See L<Win32>.
8fe0a5c4 1451
9fe6733a
PM
1452=item DBM Filters
1453
1454A new feature called "DBM Filters" has been added to all the
14218588
GS
1455DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File.
1456DBM Filters add four new methods to each DBM module:
9fe6733a
PM
1457
1458 filter_store_key
1459 filter_store_value
1460 filter_fetch_key
1461 filter_fetch_value
1462
14218588 1463These can be used to filter key-value pairs before the pairs are
9fe6733a
PM
1464written to the database or just after they are read from the database.
1465See L<perldbmfilter> for further information.
1466
b7d8191e 1467=back
3e8c4fa0
JH
1468
1469=head2 Pragmata
1470
437784d6 1471C<use attrs> is now obsolete, and is only provided for
09bef843
SB
1472backward-compatibility. It's been replaced by the C<sub : attributes>
1473syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>.
1474
14218588 1475C<use utf8> to enable UTF-8 and Unicode support.
43165c05
GS
1476
1477C<use caller 'encoding'> allows modules to inherit pragmatic attributes
1478from the caller's context. C<encoding> is currently the only supported
1479attribute.
9d73390d 1480
4438c4b7 1481Lexical warnings pragma, C<use warnings;>, to control optional warnings.
a5222a85 1482See L<perllexwarn>.
6c67e1bb 1483
67d3893f
JH
1484C<use filetest> to control the behaviour of filetests (C<-r> C<-w>
1485...). Currently only one subpragma implemented, "use filetest
1486'access';", that uses access(2) or equivalent to check permissions
1487instead of using stat(2) as usual. This matters in filesystems
1488where there are ACLs (access control lists): the stat(2) might lie,
1489but access(2) knows better.
6c67e1bb 1490
ba8251e8
GS
1491=head1 Utility Changes
1492
a5222a85
GS
1493=head2 h2ph
1494
1495[TODO - Kurt Starsinic <kstar@chapin.edu>]
1496
1497=head2 perlcc
1498
1499C<perlcc> now supports the C and Bytecode backends. By default,
1500it generates output from the simple C backend rather than the
1501optimized C backend.
1502
1503Support for non-Unix platforms has been improved.
1504
1505=head2 h2xs
1506
1507change#4232
1508[TODO - Ilya Zakharevich <ilya@math.ohio-state.edu>]
e02fdbd2 1509
ba8251e8
GS
1510=head1 Documentation Changes
1511
5fdc711f
GS
1512=over 4
1513
883d36a6
GS
1514=item perlcompile.pod
1515
1516An introduction to using the Perl Compiler suite.
1517
c7c04614
GS
1518=item perlfilter.pod
1519
1520An introduction to writing Perl source filters.
1521
883d36a6
GS
1522=item perlhack.pod
1523
1524Some guidelines for hacking the Perl source code.
1525
5fdc711f 1526=item perlopentut.pod
f8284313 1527
5fdc711f
GS
1528A tutorial on using open() effectively.
1529
1530=item perlreftut.pod
1531
1532A tutorial that introduces the essentials of references.
1533
14218588
GS
1534=item perltootc.pod
1535
1536A tutorial on managing class data for object modules.
1537
5fdc711f 1538=back
e02fdbd2 1539
73b437c8 1540=head1 New or Changed Diagnostics
ba8251e8 1541
a99ba403
GS
1542=over 4
1543
09bef843
SB
1544=item "my sub" not yet implemented
1545
1546(F) Lexically scoped subroutines are not yet implemented. Don't try that
1547yet.
1548
a99ba403
GS
1549=item '!' allowed only after types %s
1550
1551(F) The '!' is allowed in pack() and unpack() only after certain types.
1552See L<perlfunc/pack>.
1553
1554=item / cannot take a count
1555
1556(F) You had an unpack template indicating a counted-length string,
1557but you have also specified an explicit size for the string.
1558See L<perlfunc/pack>.
1559
1560=item / must be followed by a, A or Z
1561
1562(F) You had an unpack template indicating a counted-length string,
1563which must be followed by one of the letters a, A or Z
1564to indicate what sort of string is to be unpacked.
1565See L<perlfunc/pack>.
1566
1567=item / must be followed by a*, A* or Z*
1568
437784d6 1569(F) You had a pack template indicating a counted-length string,
a99ba403
GS
1570Currently the only things that can have their length counted are a*, A* or Z*.
1571See L<perlfunc/pack>.
1572
1573=item / must follow a numeric type
1574
1575(F) You had an unpack template that contained a '#',
1576but this did not follow some numeric unpack specification.
1577See L<perlfunc/pack>.
1578
a99ba403
GS
1579=item /%s/: Unrecognized escape \\%c passed through
1580
1581(W) You used a backslash-character combination which is not recognized
1582by Perl. This combination appears in an interpolated variable or a
1028017a
JH
1583C<'>-delimited regular expression. The character was understood literally.
1584
1585=item /%s/: Unrecognized escape \\%c in character class passed through
1586
1587(W) You used a backslash-character combination which is not recognized
1588by Perl inside character classes. The character was understood literally.
a99ba403
GS
1589
1590=item /%s/ should probably be written as "%s"
1591
1592(W) You have used a pattern where Perl expected to find a string,
437784d6 1593as in the first argument to C<join>. Perl will treat the true
a99ba403
GS
1594or false result of matching the pattern against $_ as the string,
1595which is probably not what you had in mind.
1596
1597=item %s() called too early to check prototype
1598
1599(W) You've called a function that has a prototype before the parser saw a
1600definition or declaration for it, and Perl could not check that the call
1601conforms to the prototype. You need to either add an early prototype
1602declaration for the subroutine in question, or move the subroutine
1603definition ahead of the call to get proper prototype checking. Alternatively,
1604if you are certain that you're calling the function correctly, you may put
1605an ampersand before the name to avoid the warning. See L<perlsub>.
1606
afebc493
GS
1607=item %s argument is not a subroutine name
1608
1609(F) The argument to exists() for C<exists &sub> must be a subroutine
1610name, and not a subroutine call. C<exists &sub()> will generate this error.
1611
09bef843
SB
1612=item %s package attribute may clash with future reserved word: %s
1613
1614(W) A lowercase attribute name was used that had a package-specific handler.
1615That name might have a meaning to Perl itself some day, even though it
1616doesn't yet. Perhaps you should use a mixed-case attribute name, instead.
1617See L<attributes>.
1618
a99ba403 1619=item (in cleanup) %s
6b121555 1620
a99ba403
GS
1621(W) This prefix usually indicates that a DESTROY() method raised
1622the indicated exception. Since destructors are usually called by
1623the system at arbitrary points during execution, and often a vast
1624number of times, the warning is issued only once for any number
1625of failures that would otherwise result in the same message being
1626repeated.
1627
1628Failure of user callbacks dispatched using the C<G_KEEPERR> flag
1629could also result in this warning. See L<perlcall/G_KEEPERR>.
1630
1631=item <> should be quotes
1632
1633(F) You wrote C<require E<lt>fileE<gt>> when you should have written
1634C<require 'file'>.
1635
1636=item Attempt to join self
1637
1638(F) You tried to join a thread from within itself, which is an
1639impossible task. You may be joining the wrong thread, or you may
1640need to move the join() to some other thread.
1641
1642=item Bad evalled substitution pattern
1643
1644(F) You've used the /e switch to evaluate the replacement for a
1645substitution, but perl found a syntax error in the code to evaluate,
1646most likely an unexpected right brace '}'.
1647
1648=item Bad realloc() ignored
1649
1650(S) An internal routine called realloc() on something that had never been
1651malloc()ed in the first place. Mandatory, but can be disabled by
1652setting environment variable C<PERL_BADFREE> to 1.
1653
1654=item Binary number > 0b11111111111111111111111111111111 non-portable
1655
1656(W) The binary number you specified is larger than 2**32-1
1657(4294967295) and therefore non-portable between systems. See
1658L<perlport> for more on portability concerns.
1659
1660=item Bit vector size > 32 non-portable
1661
1662(W) Using bit vector sizes larger than 32 is non-portable.
1663
1664=item Buffer overflow in prime_env_iter: %s
1665
1666(W) A warning peculiar to VMS. While Perl was preparing to iterate over
1667%ENV, it encountered a logical name or symbol definition which was too long,
1668so it was truncated to the string shown.
1669
1670=item Can't check filesystem of script "%s"
1671
1672(P) For some reason you can't check the filesystem of the script for nosuid.
1673
0b5b802d
GS
1674=item Can't ignore signal CHLD, forcing to default
1675
1676(W) Perl has detected that it is being run with the SIGCHLD signal
1677(sometimes known as SIGCLD) disabled. Since disabling this signal
1678will interfere with proper determination of exit status of child
1679processes, Perl has reset the signal to its default value.
1680This situation typically indicates that the parent program under
1681which Perl may be running (e.g. cron) is being very careless.
1682
a99ba403
GS
1683=item Can't modify non-lvalue subroutine call
1684
437784d6
GS
1685(F) Subroutines meant to be used in lvalue context should be declared as
1686such, see L<perlsub/"Lvalue subroutines">.
a99ba403
GS
1687
1688=item Can't read CRTL environ
1689
1690(S) A warning peculiar to VMS. Perl tried to read an element of %ENV
1691from the CRTL's internal environment array and discovered the array was
1692missing. You need to figure out where your CRTL misplaced its environ
1693or define F<PERL_ENV_TABLES> (see L<perlvms>) so that environ is not searched.
1694
1695=item Can't remove %s: %s, skipping file
1696
1697(S) You requested an inplace edit without creating a backup file. Perl
1698was unable to remove the original file to replace it with the modified
1699file. The file was left unmodified.
1700
1701=item Can't return %s from lvalue subroutine
1702
1703(F) Perl detected an attempt to return illegal lvalues (such
1704as temporary or readonly values) from a subroutine used as an lvalue.
1705This is not allowed.
1706
1707=item Can't weaken a nonreference
1708
1709(F) You attempted to weaken something that was not a reference. Only
1710references can be weakened.
1711
1712=item Character class [:%s:] unknown
1713
1714(F) The class in the character class [: :] syntax is unknown.
437784d6 1715See L<perlre>.
a99ba403
GS
1716
1717=item Character class syntax [%s] belongs inside character classes
1718
1719(W) The character class constructs [: :], [= =], and [. .] go
1720I<inside> character classes, the [] are part of the construct,
437784d6
GS
1721for example: /[012[:alpha:]345]/. Note that [= =] and [. .]
1722are not currently implemented; they are simply placeholders for
1723future extensions.
a99ba403
GS
1724
1725=item Constant is not %s reference
1726
1727(F) A constant value (perhaps declared using the C<use constant> pragma)
1728is being dereferenced, but it amounts to the wrong type of reference. The
1729message indicates the type of reference that was expected. This usually
1730indicates a syntax error in dereferencing the constant value.
1731See L<perlsub/"Constant Functions"> and L<constant>.
1732
1733=item constant(%s): %%^H is not localized
1734
1735(F) When setting compile-time-lexicalized hash %^H one should set the
1736corresponding bit of $^H as well.
1737
1738=item constant(%s): %s
1739
1740(F) Compile-time-substitutions (such as overloaded constants and
1741character names) were not correctly set up.
1742
1743=item defined(@array) is deprecated
1744
1745(D) defined() is not usually useful on arrays because it checks for an
1746undefined I<scalar> value. If you want to see if the array is empty,
1747just use C<if (@array) { # not empty }> for example.
1748
1749=item defined(%hash) is deprecated
1750
1751(D) defined() is not usually useful on hashes because it checks for an
1752undefined I<scalar> value. If you want to see if the hash is empty,
1753just use C<if (%hash) { # not empty }> for example.
1754
1755=item Did not produce a valid header
1756
1757See Server error.
1758
1759=item Document contains no data
1760
1761See Server error.
1762
1763=item entering effective %s failed
1764
1765(F) While under the C<use filetest> pragma, switching the real and
1766effective uids or gids failed.
6b121555 1767
73b437c8
JH
1768=item false [] range "%s" in regexp
1769
1770(W) A character class range must start and end at a literal character, not
1771another character class like C<\d> or C<[:alpha:]>. The "-" in your false
1772range is interpreted as a literal "-". Consider quoting the "-", "\-".
1773See L<perlre>.
1774
af8c498a 1775=item Filehandle %s opened only for output
6b121555 1776
af8c498a 1777(W) You tried to read from a filehandle opened only for writing. If you
437784d6 1778intended it to be a read/write filehandle, you needed to open it with
af8c498a
GS
1779"+E<lt>" or "+E<gt>" or "+E<gt>E<gt>" instead of with "E<lt>" or nothing. If
1780you intended only to read from the file, use "E<lt>". See
1781L<perlfunc/open>.
e02fdbd2 1782
a99ba403
GS
1783=item Hexadecimal number > 0xffffffff non-portable
1784
1785(W) The hexadecimal number you specified is larger than 2**32-1
1786(4294967295) and therefore non-portable between systems. See
1787L<perlport> for more on portability concerns.
1788
1789=item Ill-formed CRTL environ value "%s"
1790
1791(W) A warning peculiar to VMS. Perl tried to read the CRTL's internal
1792environ array, and encountered an element without the C<=> delimiter
1793used to spearate keys from values. The element is ignored.
1794
1795=item Ill-formed message in prime_env_iter: |%s|
1796
1797(W) A warning peculiar to VMS. Perl tried to read a logical name
1798or CLI symbol definition when preparing to iterate over %ENV, and
1799didn't see the expected delimiter between key and value, so the
1800line was ignored.
1801
1802=item Illegal binary digit %s
1803
437784d6 1804(F) You used a digit other than 0 or 1 in a binary number.
a99ba403
GS
1805
1806=item Illegal binary digit %s ignored
1807
1808(W) You may have tried to use a digit other than 0 or 1 in a binary number.
1809Interpretation of the binary number stopped before the offending digit.
1810
1811=item Illegal number of bits in vec
1812
1813(F) The number of bits in vec() (the third argument) must be a power of
1814two from 1 to 32 (or 64, if your platform supports that).
1815
1816=item Integer overflow in %s number
1817
1818(W) The hexadecimal, octal or binary number you have specified either
c6edd1b7 1819as a literal or as an argument to hex() or oct() is too big for your
a99ba403
GS
1820architecture, and has been converted to a floating point number. On a
182132-bit architecture the largest hexadecimal, octal or binary number
1822representable without overflow is 0xFFFFFFFF, 037777777777, or
18230b11111111111111111111111111111111 respectively. Note that Perl
1824transparently promotes all numbers to a floating point representation
1825internally--subject to loss of precision errors in subsequent
1826operations.
1827
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SB
1828=item Invalid %s attribute: %s
1829
1830The indicated attribute for a subroutine or variable was not recognized
1831by Perl or by a user-supplied handler. See L<attributes>.
1832
1833=item Invalid %s attributes: %s
1834
1835The indicated attributes for a subroutine or variable were not recognized
1836by Perl or by a user-supplied handler. See L<attributes>.
1837
73b437c8
JH
1838=item invalid [] range "%s" in regexp
1839
1840The offending range is now explicitly displayed.
1841
09bef843
SB
1842=item Invalid separator character %s in attribute list
1843
1844(F) Something other than a comma or whitespace was seen between the
1845elements of an attribute list. If the previous attribute
1846had a parenthesised parameter list, perhaps that list was terminated
1847too soon. See L<attributes>.
1848
a99ba403
GS
1849=item Invalid separator character %s in subroutine attribute list
1850
1851(F) Something other than a comma or whitespace was seen between the
1852elements of a subroutine attribute list. If the previous attribute
1853had a parenthesised parameter list, perhaps that list was terminated
1854too soon.
1855
1856=item leaving effective %s failed
1857
1858(F) While under the C<use filetest> pragma, switching the real and
1859effective uids or gids failed.
1860
1861=item Lvalue subs returning %s not implemented yet
1862
1863(F) Due to limitations in the current implementation, array and hash
1864values cannot be returned in subroutines used in lvalue context.
1865See L<perlsub/"Lvalue subroutines">.
1866
1867=item Method %s not permitted
1868
1869See Server error.
1870
1871=item Missing %sbrace%s on \N{}
1872
1873(F) Wrong syntax of character name literal C<\N{charname}> within
1874double-quotish context.
1875
06eaf0bc
GS
1876=item Missing command in piped open
1877
1878(W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
1879construction, but the command was missing or blank.
1880
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SB
1881=item Missing name in "my sub"
1882
1883(F) The reserved syntax for lexically scoped subroutines requires that they
1884have a name with which they can be found.
1885
a99ba403
GS
1886=item no UTC offset information; assuming local time is UTC
1887
1888(S) A warning peculiar to VMS. Perl was unable to find the local
1889timezone offset, so it's assuming that local system time is equivalent
1890to UTC. If it's not, define the logical name F<SYS$TIMEZONE_DIFFERENTIAL>
1891to translate to the number of seconds which need to be added to UTC to
1892get local time.
1893
1894=item Octal number > 037777777777 non-portable
1895
1896(W) The octal number you specified is larger than 2**32-1 (4294967295)
1897and therefore non-portable between systems. See L<perlport> for more
1898on portability concerns.
1899
1900See also L<perlport> for writing portable code.
1901
1902=item panic: del_backref
1903
1904(P) Failed an internal consistency check while trying to reset a weak
1905reference.
1906
1907=item panic: kid popen errno read
1908
1909(F) forked child returned an incomprehensible message about its errno.
1910
1911=item panic: magic_killbackrefs
1912
1913(P) Failed an internal consistency check while trying to reset all weak
1914references to an object.
1915
1916=item Possible Y2K bug: %s
1917
1918(W) You are concatenating the number 19 with another number, which
1919could be a potential Year 2000 problem.
1920
1921=item Premature end of script headers
1922
1923See Server error.
1924
0b5b802d
GS
1925=item Repeat count in pack overflows
1926
1927(F) You can't specify a repeat count so large that it overflows
1928your signed integers. See L<perlfunc/pack>.
1929
1930=item Repeat count in unpack overflows
1931
1932(F) You can't specify a repeat count so large that it overflows
1933your signed integers. See L<perlfunc/unpack>.
1934
a99ba403
GS
1935=item realloc() of freed memory ignored
1936
1937(S) An internal routine called realloc() on something that had already
1938been freed.
1939
1940=item Reference is already weak
1941
1942(W) You have attempted to weaken a reference that is already weak.
1943Doing so has no effect.
1944
1945=item setpgrp can't take arguments
1946
1947(F) Your system has the setpgrp() from BSD 4.2, which takes no arguments,
1948unlike POSIX setpgid(), which takes a process ID and process group ID.
1949
1950=item Strange *+?{} on zero-length expression
1951
1952(W) You applied a regular expression quantifier in a place where it
1953makes no sense, such as on a zero-width assertion.
1954Try putting the quantifier inside the assertion instead. For example,
1955the way to match "abc" provided that it is followed by three
1956repetitions of "xyz" is C</abc(?=(?:xyz){3})/>, not C</abc(?=xyz){3}/>.
1957
1958=item switching effective %s is not implemented
1959
1960(F) While under the C<use filetest> pragma, we cannot switch the
1961real and effective uids or gids.
1962
437784d6 1963=item This Perl can't reset CRTL environ elements (%s)
a99ba403
GS
1964
1965=item This Perl can't set CRTL environ elements (%s=%s)
1966
1967(W) Warnings peculiar to VMS. You tried to change or delete an element
1968of the CRTL's internal environ array, but your copy of Perl wasn't
1969built with a CRTL that contained the setenv() function. You'll need to
1970rebuild Perl with a CRTL that does, or redefine F<PERL_ENV_TABLES> (see
1971L<perlvms>) so that the environ array isn't the target of the change to
1972%ENV which produced the warning.
1973
1974=item Unknown open() mode '%s'
1975
437784d6
GS
1976(F) The second argument of 3-argument open() is not among the list
1977of valid modes: C<L<lt>>, C<L<gt>>, C<E<gt>E<gt>>, C<+L<lt>>,
1978C<+L<gt>>, C<+E<gt>E<gt>>, C<-|>, C<|->.
a99ba403
GS
1979
1980=item Unknown process %x sent message to prime_env_iter: %s
1981
1982(P) An error peculiar to VMS. Perl was reading values for %ENV before
1983iterating over it, and someone else stuck a message in the stream of
1984data Perl expected. Someone's very confused, or perhaps trying to
1985subvert Perl's population of %ENV for nefarious purposes.
1986
af8c498a
GS
1987=item Unrecognized escape \\%c passed through
1988
1989(W) You used a backslash-character combination which is not recognized
1028017a 1990by Perl. The character was understood literally.
af8c498a 1991
09bef843
SB
1992=item Unterminated attribute parameter in attribute list
1993
1994(F) The lexer saw an opening (left) parenthesis character while parsing an
1995attribute list, but the matching closing (right) parenthesis
1996character was not found. You may need to add (or remove) a backslash
1997character to get your parentheses to balance. See L<attributes>.
1998
1999=item Unterminated attribute list
2000
2001(F) The lexer found something other than a simple identifier at the start
2002of an attribute, and it wasn't a semicolon or the start of a
2003block. Perhaps you terminated the parameter list of the previous attribute
2004too soon. See L<attributes>.
2005
09bef843
SB
2006=item Unterminated attribute parameter in subroutine attribute list
2007
2008(F) The lexer saw an opening (left) parenthesis character while parsing a
2009subroutine attribute list, but the matching closing (right) parenthesis
2010character was not found. You may need to add (or remove) a backslash
2011character to get your parentheses to balance.
2012
2013=item Unterminated subroutine attribute list
2014
2015(F) The lexer found something other than a simple identifier at the start
2016of a subroutine attribute, and it wasn't a semicolon or the start of a
2017block. Perhaps you terminated the parameter list of the previous attribute
2018too soon.
2019
a99ba403 2020=item Value of CLI symbol "%s" too long
eb6e2d6f 2021
a99ba403
GS
2022(W) A warning peculiar to VMS. Perl tried to read the value of an %ENV
2023element from a CLI symbol table, and found a resultant string longer
2024than 1024 characters. The return value has been truncated to 1024
2025characters.
eb6e2d6f 2026
a99ba403 2027=item Version number must be a constant number
ba8251e8 2028
a99ba403
GS
2029(P) The attempt to translate a C<use Module n.n LIST> statement into
2030its equivalent C<BEGIN> block found an internal inconsistency with
2031the version number.
2032
2033=back
27806c82 2034
a5222a85 2035=head1 Obsolete Diagnostics
3175b8cd 2036
a99ba403
GS
2037=over 4
2038
2039=item Character class syntax [: :] is reserved for future extensions
2040
2041(W) Within regular expression character classes ([]) the syntax beginning
2042with "[:" and ending with ":]" is reserved for future extensions.
2043If you need to represent those character sequences inside a regular
2044expression character class, just quote the square brackets with the
2045backslash: "\[:" and ":\]".
2046
2047=item Ill-formed logical name |%s| in prime_env_iter
2048
2049(W) A warning peculiar to VMS. A logical name was encountered when preparing
2050to iterate over %ENV which violates the syntactic rules governing logical
2051names. Because it cannot be translated normally, it is skipped, and will not
2052appear in %ENV. This may be a benign occurrence, as some software packages
2053might directly modify logical name tables and introduce nonstandard names,
2054or it may indicate that a logical name table has been corrupted.
2055
2056=item regexp too big
2057
2058(F) The current implementation of regular expressions uses shorts as
2059address offsets within a string. Unfortunately this means that if
2060the regular expression compiles to longer than 32767, it'll blow up.
2061Usually when you want a regular expression this big, there is a better
2062way to do it with multiple statements. See L<perlre>.
2063
2064=item Use of "$$<digit>" to mean "${$}<digit>" is deprecated
2065
2066(D) Perl versions before 5.004 misinterpreted any type marker followed
2067by "$" and a digit. For example, "$$0" was incorrectly taken to mean
2068"${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004.
2069
2070However, the developers of Perl 5.004 could not fix this bug completely,
2071because at least two widely-used modules depend on the old meaning of
2072"$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the
2073old (broken) way inside strings; but it generates this message as a
2074warning. And in Perl 5.005, this special treatment will cease.
2075
2076=back
3175b8cd 2077
ba8251e8
GS
2078=head1 BUGS
2079
437784d6 2080If you find what you think is a bug, you might check the
14218588 2081articles recently posted to the comp.lang.perl.misc newsgroup.
ba8251e8
GS
2082There may also be information at http://www.perl.com/perl/, the Perl
2083Home Page.
2084
2085If you believe you have an unreported bug, please run the B<perlbug>
14218588 2086program included with your release. Make sure to trim your bug down
ba8251e8 2087to a tiny but sufficient test case. Your bug report, along with the
14218588 2088output of C<perl -V>, will be sent off to perlbug@perl.com to be
ba8251e8
GS
2089analysed by the Perl porting team.
2090
2091=head1 SEE ALSO
2092
2093The F<Changes> file for exhaustive details on what changed.
2094
2095The F<INSTALL> file for how to build Perl.
2096
2097The F<README> file for general stuff.
2098
2099The F<Artistic> and F<Copying> files for copyright information.
2100
2101=head1 HISTORY
2102
a5222a85
GS
2103Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many
2104contributions from The Perl Porters.
ba8251e8
GS
2105
2106Send omissions or corrections to <F<perlbug@perl.com>>.
2107
2108=cut