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1 | =head1 NAME |
2 | |
3 | perldelta - what's new for perl5.005 |
4 | |
5 | =head1 DESCRIPTION |
6 | |
7 | This document describes differences between the 5.004 release and this one. |
8 | |
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9 | [XXX this needs more verbose summaries of the sub topics, instead of just |
10 | the "See L<foo>." Scheduled for a second iteration. GSAR] |
11 | |
12 | =head1 About the new versioning system |
13 | |
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14 | =head1 Incompatible Changes |
15 | |
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16 | =head2 WARNING: This version is not binary compatible with Perl 5.004. |
17 | |
18 | Starting with Perl 5.004_50 there were many deep and far-reaching changes |
19 | to the language internals. If you have dynamically loaded extensions |
20 | that you built under perl 5.003 or 5.004, you can continue to use them |
21 | with 5.004, but you will need to rebuild and reinstall those extensions |
22 | to use them 5.005. See L<INSTALL> for detailed instructions on how to |
23 | upgrade. |
24 | |
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25 | =head2 Default installation structure has changed |
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26 | |
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27 | The new Configure defaults are designed to allow a smooth upgrade from |
28 | 5.004 to 5.005, but you should read L<INSTALL> for a detailed |
29 | discussion of the changes in order to adapt them to your system. |
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30 | |
31 | =head2 Perl Source Compatibility |
32 | |
33 | When none of the experimental features are enabled, there should be |
34 | no user-visible Perl source compatibility issue. |
35 | |
36 | If threads are enabled, then some caveats apply. C<@_> and C<$_> become |
37 | lexical variables. The effect of this should be largely transparent to |
38 | the user, but there are some boundary conditions under which user will |
39 | need to be aware of the issues. [XXX Add e.g. here.] |
40 | |
41 | =head2 C Source Compatibility |
42 | |
43 | =item Core sources now require ANSI C compiler |
44 | |
45 | =item Enabling threads has source compatibility issues |
46 | |
47 | =head2 Binary Compatibility |
48 | |
49 | This version is NOT binary compatible with older versions. All extensions |
50 | will need to be recompiled. |
51 | |
52 | =head2 Security fixes may affect compatibility |
53 | |
54 | A few taint leaks and taint omissions have been corrected. This may lead |
55 | to "failure" of scripts that used to work with older versions. Compiling |
56 | with -DINCOMPLETE_TAINTS provides a perl with minimal amounts of changes |
57 | to the tainting behavior. But note that the resulting perl will have |
58 | known insecurities. |
59 | |
60 | Oneliners with the C<-e> switch do not create temporary files anymore. |
61 | |
62 | =head2 Relaxed new mandatory warnings introduced in 5.004 |
63 | |
64 | Many new warnings that were introduced in 5.004 have either been made |
65 | optional. Some of these warnings are still present, but perl's new |
66 | features make them less often a problem. See L<New Diagnostics>. |
67 | |
68 | =head2 Licensing |
69 | |
70 | Perl has a new Social Contract for contributors. |
71 | |
72 | Perl's documentation license has changed. |
73 | |
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74 | =head1 Core Changes |
75 | |
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76 | |
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77 | =head2 Threads |
78 | |
79 | WARNING: Threading is considered an experimental feature. Details of the |
80 | implementation may change without notice. There are known limitations |
81 | and bugs. |
82 | |
83 | See L<README.threads>. |
84 | |
85 | =head2 Compiler |
86 | |
87 | WARNING: The Compiler and related tools are considered experimental. |
88 | Features may change without notice, and there are known limitations |
89 | and bugs. |
90 | |
91 | B::Lint is an experimental module to detect and warn about suspicious |
92 | code, especially the cases that the -w switch does not detect. |
93 | |
94 | B::Deparse can be used to demystify perl code. |
95 | |
96 | See C<ext/B/README>. |
97 | |
98 | =head2 Regular Expressions |
99 | |
100 | See L<perlre> and L<perlop>. |
101 | |
102 | =head2 Improved malloc() |
103 | |
104 | See banner at the beginning of C<malloc.c> for details. |
105 | |
106 | =head2 Quicksort is internally implemented |
107 | |
108 | See C<perlfunc/sort>. |
109 | |
110 | =head2 Reliable signals |
111 | |
112 | Via Thread::Signal. |
113 | |
114 | Via switched runtime op loop. |
115 | |
116 | =head2 Reliable stack pointers |
117 | |
118 | The internals now reallocate the perl stack only at predicatable times. |
119 | In particular, magic calls never trigger reallocations of the stack, |
120 | because all reentrancy of the runtime is handled using a "stack of stacks". |
121 | This should improve reliability of cached stack pointers in XSUBs. |
122 | |
123 | =head2 Behavior of local() on composites is well-defined |
124 | |
125 | See L<perlfunc/local>. |
126 | |
127 | =head2 C<%!> is transparently tied to the L<Errno> module |
128 | |
129 | See L<perlvar>. |
130 | |
131 | =head2 Pseudo-hashes are supported |
132 | |
133 | See L<perlref>. |
134 | |
135 | =head2 C<EXPR foreach EXPR> is supported |
136 | |
137 | See L<perlsyn>. |
138 | |
139 | =head2 Slice notation on glob elements is supported |
140 | |
141 | [XXX See what?] |
142 | |
143 | =head2 Keywords can be globally overridden |
144 | |
145 | See L<perlsub>. |
146 | |
147 | =head2 C<$^E> is meaningful on Win32 |
148 | |
149 | See L<perlvar>. |
150 | |
151 | =head2 C<foreach (1..1000000)> optimized |
152 | |
153 | C<foreach (1..1000000)> is now optimized into a counting loop. It does |
154 | not try to allocate a 1000000-size list anymore. |
155 | |
156 | =head2 C<Foo::> can be used as implicitly quoted package name |
157 | |
158 | [XXX See what?] |
159 | |
160 | =head2 C<exists $Foo::{Bar::}> tests existence of a package |
161 | |
162 | [XXX See what?] |
163 | |
164 | =head2 Better locale support |
165 | |
166 | See L<perllocale>. |
167 | |
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168 | =head2 Experimental support for 64-bit platforms |
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169 | |
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170 | Perl5 has always had 64-bit support on systems with 64-bit longs. |
171 | Starting with 5.005, the beginnings of experimental support for systems |
172 | with 32-bit long and 64-bit 'long long' integers has been added. |
173 | If you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually |
174 | define it in perl.h) then perl will be built with 'long long' support. |
175 | There will be many compiler warnings, and the resultant perl may not |
176 | work on all systems. There are many other issues related to |
177 | third-party extensions and libraries. This option exists to allow |
178 | people to work on those issues. |
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179 | |
180 | =head2 prototype() returns useful results on builtins |
181 | |
182 | See L<perlfunc/prototype>. |
183 | |
184 | =head2 Re-blessing in DESTROY() supported for chaining DESTROY() methods |
185 | |
186 | See L<perlobj/Destructors>. |
187 | |
188 | =head2 All C<printf> format conversions are handled internally |
189 | |
190 | See L<perlfunc/printf>. |
191 | |
192 | =head2 New C<INIT> keyword |
193 | |
194 | C<INIT> subs are like C<BEGIN> and C<END>, but they get called just before |
195 | the perl runtime begins execution. |
196 | |
197 | [XXX Needs to be documented in perlsub or perlmod.] |
198 | |
199 | =head2 New C<lock> keyword |
200 | |
201 | To minimize impact on source compatibility this keyword is "weak", i.e., any |
202 | user-defined subroutine of the same name overrides it, unless a C<use Thread> |
203 | has been seen. |
204 | |
205 | =head2 Tied arrays are now fully supported |
206 | |
207 | See L<Tie::Array>. |
208 | |
209 | =head2 Tied handles support is better |
210 | |
211 | Several missing hooks have been added. There is also a new base class for |
212 | TIEARRAY implementations. See L<Tie::Array>. |
213 | |
214 | |
215 | =head1 Supported Platforms |
216 | |
217 | Configure has many incremental improvements. Site-wide policy for building |
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218 | perl can now be made perlsistent, via Policy.sh. Configure also records |
219 | the command-line arguments used in F<config.sh>. |
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220 | |
221 | =head2 New Platforms |
222 | |
223 | BeOS is now supported. See L<README.beos>. |
224 | |
225 | DOS is now supported under the DJGPP tools. See L<README.dos>. |
226 | |
227 | =head2 Changes in existing support |
228 | |
229 | Win32 support has been vastly enhanced. Support for Perl Object, a C++ |
230 | encapsulation of Perl. GCC and EGCS are now supported on Win32. |
231 | [XXX Perl Object needs a big explanation elsewhere, and a pointer to |
232 | that location here.] |
233 | |
234 | VMS configuration system has been rewritten. See L<README.vms>. |
235 | |
236 | OpenBSD better supported. [XXX what others?] |
237 | |
238 | =head1 Modules and Pragmata |
239 | |
240 | =head2 New Modules |
241 | |
242 | =over |
243 | |
244 | =item B |
245 | |
246 | Perl compiler and tools. See [XXX what?]. |
247 | |
248 | =item Data::Dumper |
249 | |
250 | A module to pretty print Perl data. See L<Data::Dumper>. |
251 | |
252 | =item Errno |
253 | |
254 | A module to look up errors more conveniently. See L<Errno>. |
255 | |
256 | =item File::Spec |
257 | |
258 | A portable API for file operations. |
259 | |
260 | =item ExtUtils::Installed |
261 | |
262 | Query and manage installed modules. |
263 | |
264 | =item ExtUtils::Packlist |
265 | |
266 | Manipulate .packlist files. |
267 | |
268 | =item Fatal |
269 | |
270 | Make functions/builtins succeed or die. |
271 | |
272 | =item IPC::SysV |
273 | |
274 | Constants and other support infrastructure for System V IPC operations |
275 | in perl. |
276 | |
277 | =item Test |
278 | |
279 | A framework for writing testsuites. |
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280 | |
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281 | =item Tie::Array |
282 | |
283 | Base class for tied arrays. |
284 | |
285 | =item Tie::Handle |
286 | |
287 | Base class for tied handles. |
288 | |
289 | =item Thread |
290 | |
291 | Perl thread creation, manipulation, and support. |
292 | |
293 | =item attrs |
294 | |
295 | Set subroutine attributes. |
296 | |
297 | =item fields |
298 | |
299 | Compile-time class fields. |
300 | |
301 | =item re |
302 | |
303 | Various pragmata to control behavior of regular expressions. |
304 | |
305 | =back |
306 | |
307 | =head2 Changes in existing modules |
308 | |
309 | =over |
310 | |
311 | =item CGI |
312 | |
313 | CGI has been updated to version 2.42. |
314 | |
315 | =item POSIX |
316 | |
317 | POSIX now has its own platform-specific hints files. |
318 | |
319 | =item DB_File |
320 | |
321 | DB_File supports version 2.x of Berkeley DB. See C<ext/DB_File/Changes>. |
322 | |
323 | =item MakeMaker |
324 | |
325 | MakeMaker now supports writing empty makefiles, provides a way to |
326 | specify that site umask() policy should be honored. There is also |
327 | better support for manipulation of .packlist files, and getting |
328 | information about installed modules. |
329 | |
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330 | Extensions that have both architecture-dependent and |
331 | architecture-independent files are now always installed completely in |
332 | the architecture-dependent locations. Previously, the shareable parts |
333 | were shared both across architectures and across perl versions and were |
334 | therefore liable to be overwritten with newer versions that might have |
335 | subtle incompatibilities. |
336 | |
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337 | =item CPAN |
338 | |
339 | [XXX What?] |
340 | |
341 | =item Cwd |
342 | |
343 | Cwd::cwd is faster on most platforms. |
344 | |
345 | =item Benchmark |
346 | |
347 | Keeps better time. |
348 | |
349 | =back |
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350 | |
351 | =head1 Utility Changes |
352 | |
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353 | h2ph and related utilities have been vastly overhauled. |
354 | |
355 | perlcc, a new experimental front end for the compiler is available. |
356 | |
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357 | The crude GNU configure emulator is now called configure.gnu. |
358 | |
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359 | =head1 API Changes |
360 | |
361 | =head2 Incompatible Changes |
362 | |
363 | =head2 Deprecations, Extensions |
364 | |
365 | =head2 C++ Support |
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366 | |
367 | =head1 Documentation Changes |
368 | |
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369 | Config.pm now has a glossary of variables. |
370 | |
371 | Porting/patching.pod has detailed instructions on how to create and |
372 | submit patches for perl. |
373 | |
374 | =head1 New Diagnostics |
375 | |
376 | =over |
377 | |
378 | =item Ambiguous call resolved as CORE::%s(), qualify as such or use & |
379 | |
380 | (W) A subroutine you have declared has the same name as a Perl keyword, |
381 | and you have used the name without qualification for calling one or the |
382 | other. Perl decided to call the builtin because the subroutine is |
383 | not imported. |
384 | |
385 | To force interpretation as a subroutine call, either put an ampersand |
386 | before the subroutine name, or qualify the name with its package. |
387 | Alternatively, you can import the subroutine (or pretend that it's |
388 | imported with the C<use subs> pragma). |
389 | |
390 | To silently interpret it as the Perl operator, use the C<CORE::> prefix |
391 | on the operator (e.g. C<CORE::log($x)>) or by declaring the subroutine |
392 | to be an object method (see L<attrs>). |
393 | |
394 | =item Bad index while coercing array into hash |
395 | |
396 | (F) The index looked up in the hash found as the 0'th element of a |
397 | pseudo-hash is not legal. Index values must be at 1 or greater. |
398 | See L<perlref>. |
399 | |
400 | =item Bareword "%s" refers to nonexistent package |
401 | |
402 | (W) You used a qualified bareword of the form C<Foo::>, but |
403 | the compiler saw no other uses of that namespace before that point. |
404 | Perhaps you need to predeclare a package? |
405 | |
406 | =item Can't call method "%s" on an undefined value |
407 | |
408 | (F) You used the syntax of a method call, but the slot filled by the |
409 | object reference or package name contains an undefined value. |
410 | Something like this will reproduce the error: |
411 | |
412 | $BADREF = 42; |
413 | process $BADREF 1,2,3; |
414 | $BADREF->process(1,2,3); |
415 | |
416 | =item Can't coerce array into hash |
417 | |
418 | (F) You used an array where a hash was expected, but the array has no |
419 | information on how to map from keys to array indices. You can do that |
420 | only with arrays that have a hash reference at index 0. |
421 | |
422 | =item Can't goto subroutine from an eval-string |
423 | |
424 | (F) The "goto subroutine" call can't be used to jump out of an eval "string". |
425 | (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.) |
426 | |
427 | =item Can't use %%! because Errno.pm is not available |
428 | |
429 | (F) The first time the %! hash is used, perl automatically loads the |
430 | Errno.pm module. The Errno module is expected to tie the %! hash to |
431 | provide symbolic names for C<$!> errno values. |
432 | |
433 | =item Can't use %%! because Errno.pm is not available |
434 | |
435 | (F) The first time the %! hash is used, perl automatically loads the |
436 | Errno.pm module. The Errno module is expected to tie the %! hash to |
437 | provide symbolic names for C<$!> errno values. |
438 | |
439 | =item Cannot find an opnumber for "%s" |
440 | |
441 | (F) A string of a form C<CORE::word> was given to prototype(), but |
442 | there is no builtin with the name C<word>. |
443 | |
444 | =item Character class syntax [. .] is reserved for future extensions |
445 | |
446 | (W) Within regular expression character classes ([]) the syntax beginning |
447 | with "[." and ending with ".]" is reserved for future extensions. |
448 | If you need to represent those character sequences inside a regular |
449 | expression character class, just quote the square brackets with the |
450 | backslash: "\[." and ".\]". |
451 | |
452 | =item Character class syntax [: :] is reserved for future extensions |
453 | |
454 | (W) Within regular expression character classes ([]) the syntax beginning |
455 | with "[:" and ending with ":]" is reserved for future extensions. |
456 | If you need to represent those character sequences inside a regular |
457 | expression character class, just quote the square brackets with the |
458 | backslash: "\[:" and ":\]". |
459 | |
460 | =item Character class syntax [= =] is reserved for future extensions |
461 | |
462 | (W) Within regular expression character classes ([]) the syntax |
463 | beginning with "[=" and ending with "=]" is reserved for future extensions. |
464 | If you need to represent those character sequences inside a regular |
465 | expression character class, just quote the square brackets with the |
466 | backslash: "\[=" and "=\]". |
467 | |
468 | =item %s: Eval-group in insecure regular expression |
469 | |
470 | (F) Perl detected tainted data when trying to compile a regular expression |
471 | that contains the C<(?{ ... })> zero-width assertion, which is unsafe. |
472 | See L<perlre/(?{ code })>, and L<perlsec>. |
473 | |
474 | =item %s: Eval-group not allowed, use re 'eval' |
475 | |
476 | (F) A regular expression contained the C<(?{ ... })> zero-width assertion, |
477 | but that construct is only allowed when the C<use re 'eval'> pragma is |
478 | in effect. See L<perlre/(?{ code })>. |
479 | |
480 | =item %s: Eval-group not allowed at run time |
481 | |
482 | (F) Perl tried to compile a regular expression containing the C<(?{ ... })> |
483 | zero-width assertion at run time, as it would when the pattern contains |
484 | interpolated values. Since that is a security risk, it is not allowed. |
485 | If you insist, you may still do this by explicitly building the pattern |
486 | from an interpolated string at run time and using that in an eval(). |
487 | See L<perlre/(?{ code })>. |
488 | |
489 | =item Explicit blessing to '' (assuming package main) |
490 | |
491 | (W) You are blessing a reference to a zero length string. This has |
492 | the effect of blessing the reference into the package main. This is |
493 | usually not what you want. Consider providing a default target |
494 | package, e.g. bless($ref, $p or 'MyPackage'); |
495 | |
496 | =item Illegal hex digit ignored |
497 | |
498 | (W) You may have tried to use a character other than 0 - 9 or A - F in a |
499 | hexadecimal number. Interpretation of the hexadecimal number stopped |
500 | before the illegal character. |
501 | |
502 | =item No such array field |
503 | |
504 | (F) You tried to access an array as a hash, but the field name used is |
505 | not defined. The hash at index 0 should map all valid field names to |
506 | array indices for that to work. |
507 | |
508 | =item No such field "%s" in variable %s of type %s |
509 | |
510 | (F) You tried to access a field of a typed variable where the type |
511 | does not know about the field name. The field names are looked up in |
512 | the %FIELDS hash in the type package at compile time. The %FIELDS hash |
513 | is usually set up with the 'fields' pragma. |
514 | |
515 | =item Out of memory during ridiculously large request |
516 | |
517 | (F) You can't allocate more than 2^31+"small amount" bytes. This error |
518 | is most likely to be caused by a typo in the Perl program. e.g., C<$arr[time]> |
519 | instead of C<$arr[$time]>. |
520 | |
521 | =item Range iterator outside integer range |
522 | |
523 | (F) One (or both) of the numeric arguments to the range operator ".." |
524 | are outside the range which can be represented by integers internally. |
525 | One possible workaround is to force Perl to use magical string |
526 | increment by prepending "0" to your numbers. |
527 | |
528 | =item Recursive inheritance detected while looking for method '%s' in package '%s' |
529 | |
530 | (F) More than 100 levels of inheritance were encountered while invoking a |
531 | method. Probably indicates an unintended loop in your inheritance hierarchy. |
532 | |
533 | =item Reference found where even-sized list expected |
534 | |
535 | (W) You gave a single reference where Perl was expecting a list with |
536 | an even number of elements (for assignment to a hash). This |
537 | usually means that you used the anon hash constructor when you meant |
538 | to use parens. In any case, a hash requires key/value B<pairs>. |
539 | |
540 | %hash = { one => 1, two => 2, }; # WRONG |
541 | %hash = [ qw/ an anon array / ]; # WRONG |
542 | %hash = ( one => 1, two => 2, ); # right |
543 | %hash = qw( one 1 two 2 ); # also fine |
544 | |
545 | =item Undefined value assigned to typeglob |
546 | |
547 | (W) An undefined value was assigned to a typeglob, a la C<*foo = undef>. |
548 | This does nothing. It's possible that you really mean C<undef *foo>. |
549 | |
550 | =item Use of reserved word "%s" is deprecated |
551 | |
552 | (D) The indicated bareword is a reserved word. Future versions of perl |
553 | may use it as a keyword, so you're better off either explicitly quoting |
554 | the word in a manner appropriate for its context of use, or using a |
555 | different name altogether. The warning can be suppressed for subroutine |
556 | names by either adding a C<&> prefix, or using a package qualifier, |
557 | e.g. C<&our()>, or C<Foo::our()>. |
558 | |
559 | =item perl: warning: Setting locale failed. |
560 | |
561 | (S) The whole warning message will look something like: |
562 | |
563 | perl: warning: Setting locale failed. |
564 | perl: warning: Please check that your locale settings: |
565 | LC_ALL = "En_US", |
566 | LANG = (unset) |
567 | are supported and installed on your system. |
568 | perl: warning: Falling back to the standard locale ("C"). |
569 | |
570 | Exactly what were the failed locale settings varies. In the above the |
571 | settings were that the LC_ALL was "En_US" and the LANG had no value. |
572 | This error means that Perl detected that you and/or your system |
573 | administrator have set up the so-called variable system but Perl could |
574 | not use those settings. This was not dead serious, fortunately: there |
575 | is a "default locale" called "C" that Perl can and will use, the |
576 | script will be run. Before you really fix the problem, however, you |
577 | will get the same error message each time you run Perl. How to really |
578 | fix the problem can be found in L<perllocale> section B<LOCALE PROBLEMS>. |
579 | |
580 | =back |
581 | |
582 | |
583 | =head1 Obsolete Diagnostics |
584 | |
585 | =over |
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586 | |
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587 | =item Can't mktemp() |
588 | |
589 | (F) The mktemp() routine failed for some reason while trying to process |
590 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. |
591 | |
592 | =item Can't write to temp file for B<-e>: %s |
593 | |
594 | (F) The write routine failed for some reason while trying to process |
595 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. |
596 | |
597 | =item Cannot open temporary file |
598 | |
599 | (F) The create routine failed for some reason while trying to process |
600 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. |
601 | |
602 | |
603 | =back |
604 | |
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605 | =head1 BUGS |
606 | |
607 | If you find what you think is a bug, you might check the headers of |
608 | recently posted articles in the comp.lang.perl.misc newsgroup. |
609 | There may also be information at http://www.perl.com/perl/, the Perl |
610 | Home Page. |
611 | |
612 | If you believe you have an unreported bug, please run the B<perlbug> |
613 | program included with your release. Make sure you trim your bug down |
614 | to a tiny but sufficient test case. Your bug report, along with the |
615 | output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be |
616 | analysed by the Perl porting team. |
617 | |
618 | =head1 SEE ALSO |
619 | |
620 | The F<Changes> file for exhaustive details on what changed. |
621 | |
622 | The F<INSTALL> file for how to build Perl. |
623 | |
624 | The F<README> file for general stuff. |
625 | |
626 | The F<Artistic> and F<Copying> files for copyright information. |
627 | |
628 | =head1 HISTORY |
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629 | |
630 | =cut |