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1 | =head1 NAME |
2 | ||
3 | perl5005delta - 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 | ||
9 | =head1 About the new versioning system | |
10 | ||
11 | Perl is now developed on two tracks: a maintenance track that makes | |
12 | small, safe updates to released production versions with emphasis on | |
13 | compatibility; and a development track that pursues more aggressive | |
14 | evolution. Maintenance releases (which should be considered production | |
15 | quality) have subversion numbers that run from C<1> to C<49>, and | |
16 | development releases (which should be considered "alpha" quality) run | |
17 | from C<50> to C<99>. | |
18 | ||
19 | Perl 5.005 is the combined product of the new dual-track development | |
20 | scheme. | |
21 | ||
22 | =head1 Incompatible Changes | |
23 | ||
24 | =head2 WARNING: This version is not binary compatible with Perl 5.004. | |
25 | ||
26 | Starting with Perl 5.004_50 there were many deep and far-reaching changes | |
27 | to the language internals. If you have dynamically loaded extensions | |
28 | that you built under perl 5.003 or 5.004, you can continue to use them | |
29 | with 5.004, but you will need to rebuild and reinstall those extensions | |
30 | to use them 5.005. See F<INSTALL> for detailed instructions on how to | |
31 | upgrade. | |
32 | ||
33 | =head2 Default installation structure has changed | |
34 | ||
35 | The new Configure defaults are designed to allow a smooth upgrade from | |
36 | 5.004 to 5.005, but you should read F<INSTALL> for a detailed | |
37 | discussion of the changes in order to adapt them to your system. | |
38 | ||
39 | =head2 Perl Source Compatibility | |
40 | ||
41 | When none of the experimental features are enabled, there should be | |
42 | very few user-visible Perl source compatibility issues. | |
43 | ||
44 | If threads are enabled, then some caveats apply. C<@_> and C<$_> become | |
45 | lexical variables. The effect of this should be largely transparent to | |
46 | the user, but there are some boundary conditions under which user will | |
47 | need to be aware of the issues. For example, C<local(@_)> results in | |
48 | a "Can't localize lexical variable @_ ..." message. This may be enabled | |
49 | in a future version. | |
50 | ||
51 | Some new keywords have been introduced. These are generally expected to | |
52 | have very little impact on compatibility. See L<New C<INIT> keyword>, | |
53 | L<New C<lock> keyword>, and L<New C<qrE<sol>E<sol>> operator>. | |
54 | ||
55 | Certain barewords are now reserved. Use of these will provoke a warning | |
56 | if you have asked for them with the C<-w> switch. | |
57 | See L<C<our> is now a reserved word>. | |
58 | ||
59 | =head2 C Source Compatibility | |
60 | ||
61 | There have been a large number of changes in the internals to support | |
62 | the new features in this release. | |
63 | ||
64 | =over 4 | |
65 | ||
66 | =item * | |
67 | ||
68 | Core sources now require ANSI C compiler | |
69 | ||
70 | An ANSI C compiler is now B<required> to build perl. See F<INSTALL>. | |
71 | ||
72 | =item * | |
73 | ||
74 | All Perl global variables must now be referenced with an explicit prefix | |
75 | ||
76 | All Perl global variables that are visible for use by extensions now | |
77 | have a C<PL_> prefix. New extensions should C<not> refer to perl globals | |
78 | by their unqualified names. To preserve sanity, we provide limited | |
79 | backward compatibility for globals that are being widely used like | |
80 | C<sv_undef> and C<na> (which should now be written as C<PL_sv_undef>, | |
81 | C<PL_na> etc.) | |
82 | ||
83 | If you find that your XS extension does not compile anymore because a | |
84 | perl global is not visible, try adding a C<PL_> prefix to the global | |
85 | and rebuild. | |
86 | ||
87 | It is strongly recommended that all functions in the Perl API that don't | |
88 | begin with C<perl> be referenced with a C<Perl_> prefix. The bare function | |
89 | names without the C<Perl_> prefix are supported with macros, but this | |
90 | support may cease in a future release. | |
91 | ||
92 | See L<perlapi>. | |
93 | ||
94 | =item * | |
95 | ||
96 | Enabling threads has source compatibility issues | |
97 | ||
98 | Perl built with threading enabled requires extensions to use the new | |
99 | C<dTHR> macro to initialize the handle to access per-thread data. | |
100 | If you see a compiler error that talks about the variable C<thr> not | |
101 | being declared (when building a module that has XS code), you need | |
102 | to add C<dTHR;> at the beginning of the block that elicited the error. | |
103 | ||
104 | The API function C<perl_get_sv("@",FALSE)> should be used instead of | |
105 | directly accessing perl globals as C<GvSV(errgv)>. The API call is | |
106 | backward compatible with existing perls and provides source compatibility | |
107 | with threading is enabled. | |
108 | ||
109 | See L<"C Source Compatibility"> for more information. | |
110 | ||
111 | =back | |
112 | ||
113 | =head2 Binary Compatibility | |
114 | ||
115 | This version is NOT binary compatible with older versions. All extensions | |
116 | will need to be recompiled. Further binaries built with threads enabled | |
117 | are incompatible with binaries built without. This should largely be | |
118 | transparent to the user, as all binary incompatible configurations have | |
119 | their own unique architecture name, and extension binaries get installed at | |
120 | unique locations. This allows coexistence of several configurations in | |
121 | the same directory hierarchy. See F<INSTALL>. | |
122 | ||
123 | =head2 Security fixes may affect compatibility | |
124 | ||
125 | A few taint leaks and taint omissions have been corrected. This may lead | |
126 | to "failure" of scripts that used to work with older versions. Compiling | |
127 | with -DINCOMPLETE_TAINTS provides a perl with minimal amounts of changes | |
128 | to the tainting behavior. But note that the resulting perl will have | |
129 | known insecurities. | |
130 | ||
131 | Oneliners with the C<-e> switch do not create temporary files anymore. | |
132 | ||
133 | =head2 Relaxed new mandatory warnings introduced in 5.004 | |
134 | ||
135 | Many new warnings that were introduced in 5.004 have been made | |
136 | optional. Some of these warnings are still present, but perl's new | |
137 | features make them less often a problem. See L<New Diagnostics>. | |
138 | ||
139 | =head2 Licensing | |
140 | ||
141 | Perl has a new Social Contract for contributors. See F<Porting/Contract>. | |
142 | ||
143 | The license included in much of the Perl documentation has changed. | |
144 | Most of the Perl documentation was previously under the implicit GNU | |
145 | General Public License or the Artistic License (at the user's choice). | |
146 | Now much of the documentation unambiguously states the terms under which | |
147 | it may be distributed. Those terms are in general much less restrictive | |
148 | than the GNU GPL. See L<perl> and the individual perl manpages listed | |
149 | therein. | |
150 | ||
151 | =head1 Core Changes | |
152 | ||
153 | ||
154 | =head2 Threads | |
155 | ||
156 | WARNING: Threading is considered an B<experimental> feature. Details of the | |
157 | implementation may change without notice. There are known limitations | |
158 | and some bugs. These are expected to be fixed in future versions. | |
159 | ||
160 | See F<README.threads>. | |
161 | ||
162 | =head2 Compiler | |
163 | ||
164 | WARNING: The Compiler and related tools are considered B<experimental>. | |
165 | Features may change without notice, and there are known limitations | |
166 | and bugs. Since the compiler is fully external to perl, the default | |
167 | configuration will build and install it. | |
168 | ||
169 | The Compiler produces three different types of transformations of a | |
170 | perl program. The C backend generates C code that captures perl's state | |
171 | just before execution begins. It eliminates the compile-time overheads | |
172 | of the regular perl interpreter, but the run-time performance remains | |
173 | comparatively the same. The CC backend generates optimized C code | |
174 | equivalent to the code path at run-time. The CC backend has greater | |
175 | potential for big optimizations, but only a few optimizations are | |
176 | implemented currently. The Bytecode backend generates a platform | |
177 | independent bytecode representation of the interpreter's state | |
178 | just before execution. Thus, the Bytecode back end also eliminates | |
179 | much of the compilation overhead of the interpreter. | |
180 | ||
181 | The compiler comes with several valuable utilities. | |
182 | ||
183 | C<B::Lint> is an experimental module to detect and warn about suspicious | |
184 | code, especially the cases that the C<-w> switch does not detect. | |
185 | ||
186 | C<B::Deparse> can be used to demystify perl code, and understand | |
187 | how perl optimizes certain constructs. | |
188 | ||
189 | C<B::Xref> generates cross reference reports of all definition and use | |
190 | of variables, subroutines and formats in a program. | |
191 | ||
192 | C<B::Showlex> show the lexical variables used by a subroutine or file | |
193 | at a glance. | |
194 | ||
195 | C<perlcc> is a simple frontend for compiling perl. | |
196 | ||
197 | See C<ext/B/README>, L<B>, and the respective compiler modules. | |
198 | ||
199 | =head2 Regular Expressions | |
200 | ||
201 | Perl's regular expression engine has been seriously overhauled, and | |
202 | many new constructs are supported. Several bugs have been fixed. | |
203 | ||
204 | Here is an itemized summary: | |
205 | ||
206 | =over 4 | |
207 | ||
208 | =item Many new and improved optimizations | |
209 | ||
210 | Changes in the RE engine: | |
211 | ||
212 | Unneeded nodes removed; | |
213 | Substrings merged together; | |
214 | New types of nodes to process (SUBEXPR)* and similar expressions | |
215 | quickly, used if the SUBEXPR has no side effects and matches | |
216 | strings of the same length; | |
217 | Better optimizations by lookup for constant substrings; | |
218 | Better search for constants substrings anchored by $ ; | |
219 | ||
220 | Changes in Perl code using RE engine: | |
221 | ||
222 | More optimizations to s/longer/short/; | |
223 | study() was not working; | |
224 | /blah/ may be optimized to an analogue of index() if $& $` $' not seen; | |
225 | Unneeded copying of matched-against string removed; | |
226 | Only matched part of the string is copying if $` $' were not seen; | |
227 | ||
228 | =item Many bug fixes | |
229 | ||
230 | Note that only the major bug fixes are listed here. See F<Changes> for others. | |
231 | ||
232 | Backtracking might not restore start of $3. | |
233 | No feedback if max count for * or + on "complex" subexpression | |
234 | was reached, similarly (but at compile time) for {3,34567} | |
235 | Primitive restrictions on max count introduced to decrease a | |
236 | possibility of a segfault; | |
237 | (ZERO-LENGTH)* could segfault; | |
238 | (ZERO-LENGTH)* was prohibited; | |
239 | Long REs were not allowed; | |
240 | /RE/g could skip matches at the same position after a | |
241 | zero-length match; | |
242 | ||
243 | =item New regular expression constructs | |
244 | ||
245 | The following new syntax elements are supported: | |
246 | ||
247 | (?<=RE) | |
248 | (?<!RE) | |
249 | (?{ CODE }) | |
250 | (?i-x) | |
251 | (?i:RE) | |
252 | (?(COND)YES_RE|NO_RE) | |
253 | (?>RE) | |
254 | \z | |
255 | ||
256 | =item New operator for precompiled regular expressions | |
257 | ||
258 | See L<New C<qrE<sol>E<sol>> operator>. | |
259 | ||
260 | =item Other improvements | |
261 | ||
262 | Better debugging output (possibly with colors), | |
263 | even from non-debugging Perl; | |
264 | RE engine code now looks like C, not like assembler; | |
265 | Behaviour of RE modifiable by `use re' directive; | |
266 | Improved documentation; | |
267 | Test suite significantly extended; | |
268 | Syntax [:^upper:] etc., reserved inside character classes; | |
269 | ||
270 | =item Incompatible changes | |
271 | ||
272 | (?i) localized inside enclosing group; | |
273 | $( is not interpolated into RE any more; | |
274 | /RE/g may match at the same position (with non-zero length) | |
275 | after a zero-length match (bug fix). | |
276 | ||
277 | =back | |
278 | ||
279 | See L<perlre> and L<perlop>. | |
280 | ||
281 | =head2 Improved malloc() | |
282 | ||
283 | See banner at the beginning of C<malloc.c> for details. | |
284 | ||
285 | =head2 Quicksort is internally implemented | |
286 | ||
287 | Perl now contains its own highly optimized qsort() routine. The new qsort() | |
288 | is resistant to inconsistent comparison functions, so Perl's C<sort()> will | |
289 | not provoke coredumps any more when given poorly written sort subroutines. | |
290 | (Some C library C<qsort()>s that were being used before used to have this | |
291 | problem.) In our testing, the new C<qsort()> required the minimal number | |
292 | of pair-wise compares on average, among all known C<qsort()> implementations. | |
293 | ||
294 | See C<perlfunc/sort>. | |
295 | ||
296 | =head2 Reliable signals | |
297 | ||
298 | Perl's signal handling is susceptible to random crashes, because signals | |
299 | arrive asynchronously, and the Perl runtime is not reentrant at arbitrary | |
300 | times. | |
301 | ||
302 | However, one experimental implementation of reliable signals is available | |
303 | when threads are enabled. See C<Thread::Signal>. Also see F<INSTALL> for | |
304 | how to build a Perl capable of threads. | |
305 | ||
306 | =head2 Reliable stack pointers | |
307 | ||
308 | The internals now reallocate the perl stack only at predictable times. | |
309 | In particular, magic calls never trigger reallocations of the stack, | |
310 | because all reentrancy of the runtime is handled using a "stack of stacks". | |
311 | This should improve reliability of cached stack pointers in the internals | |
312 | and in XSUBs. | |
313 | ||
314 | =head2 More generous treatment of carriage returns | |
315 | ||
316 | Perl used to complain if it encountered literal carriage returns in | |
317 | scripts. Now they are mostly treated like whitespace within program text. | |
318 | Inside string literals and here documents, literal carriage returns are | |
319 | ignored if they occur paired with linefeeds, or get interpreted as whitespace | |
320 | if they stand alone. This behavior means that literal carriage returns | |
321 | in files should be avoided. You can get the older, more compatible (but | |
322 | less generous) behavior by defining the preprocessor symbol | |
323 | C<PERL_STRICT_CR> when building perl. Of course, all this has nothing | |
324 | whatever to do with how escapes like C<\r> are handled within strings. | |
325 | ||
326 | Note that this doesn't somehow magically allow you to keep all text files | |
327 | in DOS format. The generous treatment only applies to files that perl | |
328 | itself parses. If your C compiler doesn't allow carriage returns in | |
329 | files, you may still be unable to build modules that need a C compiler. | |
330 | ||
331 | =head2 Memory leaks | |
332 | ||
333 | C<substr>, C<pos> and C<vec> don't leak memory anymore when used in lvalue | |
334 | context. Many small leaks that impacted applications that embed multiple | |
335 | interpreters have been fixed. | |
336 | ||
337 | =head2 Better support for multiple interpreters | |
338 | ||
339 | The build-time option C<-DMULTIPLICITY> has had many of the details | |
340 | reworked. Some previously global variables that should have been | |
341 | per-interpreter now are. With care, this allows interpreters to call | |
342 | each other. See the C<PerlInterp> extension on CPAN. | |
343 | ||
344 | =head2 Behavior of local() on array and hash elements is now well-defined | |
345 | ||
346 | See L<perlsub/"Temporary Values via local()">. | |
347 | ||
348 | =head2 C<%!> is transparently tied to the L<Errno> module | |
349 | ||
350 | See L<perlvar>, and L<Errno>. | |
351 | ||
352 | =head2 Pseudo-hashes are supported | |
353 | ||
354 | See L<perlref>. | |
355 | ||
356 | =head2 C<EXPR foreach EXPR> is supported | |
357 | ||
358 | See L<perlsyn>. | |
359 | ||
360 | =head2 Keywords can be globally overridden | |
361 | ||
362 | See L<perlsub>. | |
363 | ||
364 | =head2 C<$^E> is meaningful on Win32 | |
365 | ||
366 | See L<perlvar>. | |
367 | ||
368 | =head2 C<foreach (1..1000000)> optimized | |
369 | ||
370 | C<foreach (1..1000000)> is now optimized into a counting loop. It does | |
371 | not try to allocate a 1000000-size list anymore. | |
372 | ||
373 | =head2 C<Foo::> can be used as implicitly quoted package name | |
374 | ||
375 | Barewords caused unintuitive behavior when a subroutine with the same | |
376 | name as a package happened to be defined. Thus, C<new Foo @args>, | |
377 | use the result of the call to C<Foo()> instead of C<Foo> being treated | |
378 | as a literal. The recommended way to write barewords in the indirect | |
379 | object slot is C<new Foo:: @args>. Note that the method C<new()> is | |
380 | called with a first argument of C<Foo>, not C<Foo::> when you do that. | |
381 | ||
382 | =head2 C<exists $Foo::{Bar::}> tests existence of a package | |
383 | ||
384 | It was impossible to test for the existence of a package without | |
385 | actually creating it before. Now C<exists $Foo::{Bar::}> can be | |
386 | used to test if the C<Foo::Bar> namespace has been created. | |
387 | ||
388 | =head2 Better locale support | |
389 | ||
390 | See L<perllocale>. | |
391 | ||
392 | =head2 Experimental support for 64-bit platforms | |
393 | ||
394 | Perl5 has always had 64-bit support on systems with 64-bit longs. | |
395 | Starting with 5.005, the beginnings of experimental support for systems | |
396 | with 32-bit long and 64-bit 'long long' integers has been added. | |
397 | If you add -DUSE_LONG_LONG to your ccflags in config.sh (or manually | |
398 | define it in perl.h) then perl will be built with 'long long' support. | |
399 | There will be many compiler warnings, and the resultant perl may not | |
400 | work on all systems. There are many other issues related to | |
401 | third-party extensions and libraries. This option exists to allow | |
402 | people to work on those issues. | |
403 | ||
404 | =head2 prototype() returns useful results on builtins | |
405 | ||
406 | See L<perlfunc/prototype>. | |
407 | ||
408 | =head2 Extended support for exception handling | |
409 | ||
410 | C<die()> now accepts a reference value, and C<$@> gets set to that | |
411 | value in exception traps. This makes it possible to propagate | |
412 | exception objects. This is an undocumented B<experimental> feature. | |
413 | ||
414 | =head2 Re-blessing in DESTROY() supported for chaining DESTROY() methods | |
415 | ||
416 | See L<perlobj/Destructors>. | |
417 | ||
418 | =head2 All C<printf> format conversions are handled internally | |
419 | ||
420 | See L<perlfunc/printf>. | |
421 | ||
422 | =head2 New C<INIT> keyword | |
423 | ||
424 | C<INIT> subs are like C<BEGIN> and C<END>, but they get run just before | |
425 | the perl runtime begins execution. e.g., the Perl Compiler makes use of | |
426 | C<INIT> blocks to initialize and resolve pointers to XSUBs. | |
427 | ||
428 | =head2 New C<lock> keyword | |
429 | ||
430 | The C<lock> keyword is the fundamental synchronization primitive | |
431 | in threaded perl. When threads are not enabled, it is currently a noop. | |
432 | ||
433 | To minimize impact on source compatibility this keyword is "weak", i.e., any | |
434 | user-defined subroutine of the same name overrides it, unless a C<use Thread> | |
435 | has been seen. | |
436 | ||
437 | =head2 New C<qr//> operator | |
438 | ||
439 | The C<qr//> operator, which is syntactically similar to the other quote-like | |
440 | operators, is used to create precompiled regular expressions. This compiled | |
441 | form can now be explicitly passed around in variables, and interpolated in | |
442 | other regular expressions. See L<perlop>. | |
443 | ||
444 | =head2 C<our> is now a reserved word | |
445 | ||
446 | Calling a subroutine with the name C<our> will now provoke a warning when | |
447 | using the C<-w> switch. | |
448 | ||
449 | =head2 Tied arrays are now fully supported | |
450 | ||
451 | See L<Tie::Array>. | |
452 | ||
453 | =head2 Tied handles support is better | |
454 | ||
455 | Several missing hooks have been added. There is also a new base class for | |
456 | TIEARRAY implementations. See L<Tie::Array>. | |
457 | ||
458 | =head2 4th argument to substr | |
459 | ||
460 | substr() can now both return and replace in one operation. The optional | |
461 | 4th argument is the replacement string. See L<perlfunc/substr>. | |
462 | ||
463 | =head2 Negative LENGTH argument to splice | |
464 | ||
465 | splice() with a negative LENGTH argument now work similar to what the | |
466 | LENGTH did for substr(). Previously a negative LENGTH was treated as | |
467 | 0. See L<perlfunc/splice>. | |
468 | ||
469 | =head2 Magic lvalues are now more magical | |
470 | ||
471 | When you say something like C<substr($x, 5) = "hi">, the scalar returned | |
472 | by substr() is special, in that any modifications to it affect $x. | |
473 | (This is called a 'magic lvalue' because an 'lvalue' is something on | |
474 | the left side of an assignment.) Normally, this is exactly what you | |
475 | would expect to happen, but Perl uses the same magic if you use substr(), | |
476 | pos(), or vec() in a context where they might be modified, like taking | |
477 | a reference with C<\> or as an argument to a sub that modifies C<@_>. | |
478 | In previous versions, this 'magic' only went one way, but now changes | |
479 | to the scalar the magic refers to ($x in the above example) affect the | |
480 | magic lvalue too. For instance, this code now acts differently: | |
481 | ||
482 | $x = "hello"; | |
483 | sub printit { | |
484 | $x = "g'bye"; | |
485 | print $_[0], "\n"; | |
486 | } | |
487 | printit(substr($x, 0, 5)); | |
488 | ||
489 | In previous versions, this would print "hello", but it now prints "g'bye". | |
490 | ||
491 | =head2 <> now reads in records | |
492 | ||
493 | If C<$/> is a reference to an integer, or a scalar that holds an integer, | |
494 | <> will read in records instead of lines. For more info, see | |
495 | L<perlvar/$E<sol>>. | |
496 | ||
497 | =head1 Supported Platforms | |
498 | ||
499 | Configure has many incremental improvements. Site-wide policy for building | |
500 | perl can now be made persistent, via Policy.sh. Configure also records | |
501 | the command-line arguments used in F<config.sh>. | |
502 | ||
503 | =head2 New Platforms | |
504 | ||
505 | BeOS is now supported. See F<README.beos>. | |
506 | ||
507 | DOS is now supported under the DJGPP tools. See F<README.dos> (installed | |
508 | as L<perldos> on some systems). | |
509 | ||
510 | MiNT is now supported. See F<README.mint>. | |
511 | ||
512 | MPE/iX is now supported. See F<README.mpeix>. | |
513 | ||
514 | MVS (aka OS390, aka Open Edition) is now supported. See F<README.os390> | |
515 | (installed as L<perlos390> on some systems). | |
516 | ||
517 | Stratus VOS is now supported. See F<README.vos>. | |
518 | ||
519 | =head2 Changes in existing support | |
520 | ||
521 | Win32 support has been vastly enhanced. Support for Perl Object, a C++ | |
522 | encapsulation of Perl. GCC and EGCS are now supported on Win32. | |
523 | See F<README.win32>, aka L<perlwin32>. | |
524 | ||
525 | VMS configuration system has been rewritten. See F<README.vms> (installed | |
526 | as L<README_vms> on some systems). | |
527 | ||
528 | The hints files for most Unix platforms have seen incremental improvements. | |
529 | ||
530 | =head1 Modules and Pragmata | |
531 | ||
532 | =head2 New Modules | |
533 | ||
534 | =over 4 | |
535 | ||
536 | =item B | |
537 | ||
538 | Perl compiler and tools. See L<B>. | |
539 | ||
540 | =item Data::Dumper | |
541 | ||
542 | A module to pretty print Perl data. See L<Data::Dumper>. | |
543 | ||
544 | =item Dumpvalue | |
545 | ||
546 | A module to dump perl values to the screen. See L<Dumpvalue>. | |
547 | ||
548 | =item Errno | |
549 | ||
550 | A module to look up errors more conveniently. See L<Errno>. | |
551 | ||
552 | =item File::Spec | |
553 | ||
554 | A portable API for file operations. | |
555 | ||
556 | =item ExtUtils::Installed | |
557 | ||
558 | Query and manage installed modules. | |
559 | ||
560 | =item ExtUtils::Packlist | |
561 | ||
562 | Manipulate .packlist files. | |
563 | ||
564 | =item Fatal | |
565 | ||
566 | Make functions/builtins succeed or die. | |
567 | ||
568 | =item IPC::SysV | |
569 | ||
570 | Constants and other support infrastructure for System V IPC operations | |
571 | in perl. | |
572 | ||
573 | =item Test | |
574 | ||
575 | A framework for writing testsuites. | |
576 | ||
577 | =item Tie::Array | |
578 | ||
579 | Base class for tied arrays. | |
580 | ||
581 | =item Tie::Handle | |
582 | ||
583 | Base class for tied handles. | |
584 | ||
585 | =item Thread | |
586 | ||
587 | Perl thread creation, manipulation, and support. | |
588 | ||
589 | =item attrs | |
590 | ||
591 | Set subroutine attributes. | |
592 | ||
593 | =item fields | |
594 | ||
595 | Compile-time class fields. | |
596 | ||
597 | =item re | |
598 | ||
599 | Various pragmata to control behavior of regular expressions. | |
600 | ||
601 | =back | |
602 | ||
603 | =head2 Changes in existing modules | |
604 | ||
605 | =over 4 | |
606 | ||
607 | =item Benchmark | |
608 | ||
609 | You can now run tests for I<x> seconds instead of guessing the right | |
610 | number of tests to run. | |
611 | ||
612 | Keeps better time. | |
613 | ||
614 | =item Carp | |
615 | ||
616 | Carp has a new function cluck(). cluck() warns, like carp(), but also adds | |
617 | a stack backtrace to the error message, like confess(). | |
618 | ||
619 | =item CGI | |
620 | ||
621 | CGI has been updated to version 2.42. | |
622 | ||
623 | =item Fcntl | |
624 | ||
625 | More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for | |
626 | large (more than 4G) file access (the 64-bit support is not yet | |
627 | working, though, so no need to get overly excited), Free/Net/OpenBSD | |
628 | locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and | |
629 | O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR. | |
630 | ||
631 | =item Math::Complex | |
632 | ||
633 | The accessors methods Re, Im, arg, abs, rho, theta, methods can | |
634 | ($z->Re()) now also act as mutators ($z->Re(3)). | |
635 | ||
636 | =item Math::Trig | |
637 | ||
638 | A little bit of radial trigonometry (cylindrical and spherical) added, | |
639 | for example the great circle distance. | |
640 | ||
641 | =item POSIX | |
642 | ||
643 | POSIX now has its own platform-specific hints files. | |
644 | ||
645 | =item DB_File | |
646 | ||
647 | DB_File supports version 2.x of Berkeley DB. See C<ext/DB_File/Changes>. | |
648 | ||
649 | =item MakeMaker | |
650 | ||
651 | MakeMaker now supports writing empty makefiles, provides a way to | |
652 | specify that site umask() policy should be honored. There is also | |
653 | better support for manipulation of .packlist files, and getting | |
654 | information about installed modules. | |
655 | ||
656 | Extensions that have both architecture-dependent and | |
657 | architecture-independent files are now always installed completely in | |
658 | the architecture-dependent locations. Previously, the shareable parts | |
659 | were shared both across architectures and across perl versions and were | |
660 | therefore liable to be overwritten with newer versions that might have | |
661 | subtle incompatibilities. | |
662 | ||
663 | =item CPAN | |
664 | ||
665 | See L<perlmodinstall> and L<CPAN>. | |
666 | ||
667 | =item Cwd | |
668 | ||
669 | Cwd::cwd is faster on most platforms. | |
670 | ||
671 | =back | |
672 | ||
673 | =head1 Utility Changes | |
674 | ||
675 | C<h2ph> and related utilities have been vastly overhauled. | |
676 | ||
677 | C<perlcc>, a new experimental front end for the compiler is available. | |
678 | ||
679 | The crude GNU C<configure> emulator is now called C<configure.gnu> to | |
680 | avoid trampling on C<Configure> under case-insensitive filesystems. | |
681 | ||
682 | C<perldoc> used to be rather slow. The slower features are now optional. | |
683 | In particular, case-insensitive searches need the C<-i> switch, and | |
684 | recursive searches need C<-r>. You can set these switches in the | |
685 | C<PERLDOC> environment variable to get the old behavior. | |
686 | ||
687 | =head1 Documentation Changes | |
688 | ||
689 | Config.pm now has a glossary of variables. | |
690 | ||
691 | F<Porting/patching.pod> has detailed instructions on how to create and | |
692 | submit patches for perl. | |
693 | ||
694 | L<perlport> specifies guidelines on how to write portably. | |
695 | ||
696 | L<perlmodinstall> describes how to fetch and install modules from C<CPAN> | |
697 | sites. | |
698 | ||
699 | Some more Perl traps are documented now. See L<perltrap>. | |
700 | ||
701 | L<perlopentut> gives a tutorial on using open(). | |
702 | ||
703 | L<perlreftut> gives a tutorial on references. | |
704 | ||
705 | L<perlthrtut> gives a tutorial on threads. | |
706 | ||
707 | =head1 New Diagnostics | |
708 | ||
709 | =over 4 | |
710 | ||
711 | =item Ambiguous call resolved as CORE::%s(), qualify as such or use & | |
712 | ||
713 | (W) A subroutine you have declared has the same name as a Perl keyword, | |
714 | and you have used the name without qualification for calling one or the | |
715 | other. Perl decided to call the builtin because the subroutine is | |
716 | not imported. | |
717 | ||
718 | To force interpretation as a subroutine call, either put an ampersand | |
719 | before the subroutine name, or qualify the name with its package. | |
720 | Alternatively, you can import the subroutine (or pretend that it's | |
721 | imported with the C<use subs> pragma). | |
722 | ||
723 | To silently interpret it as the Perl operator, use the C<CORE::> prefix | |
724 | on the operator (e.g. C<CORE::log($x)>) or by declaring the subroutine | |
725 | to be an object method (see L<attrs>). | |
726 | ||
727 | =item Bad index while coercing array into hash | |
728 | ||
729 | (F) The index looked up in the hash found as the 0'th element of a | |
730 | pseudo-hash is not legal. Index values must be at 1 or greater. | |
731 | See L<perlref>. | |
732 | ||
733 | =item Bareword "%s" refers to nonexistent package | |
734 | ||
735 | (W) You used a qualified bareword of the form C<Foo::>, but | |
736 | the compiler saw no other uses of that namespace before that point. | |
737 | Perhaps you need to predeclare a package? | |
738 | ||
739 | =item Can't call method "%s" on an undefined value | |
740 | ||
741 | (F) You used the syntax of a method call, but the slot filled by the | |
742 | object reference or package name contains an undefined value. | |
743 | Something like this will reproduce the error: | |
744 | ||
745 | $BADREF = 42; | |
746 | process $BADREF 1,2,3; | |
747 | $BADREF->process(1,2,3); | |
748 | ||
749 | =item Can't check filesystem of script "%s" for nosuid | |
750 | ||
751 | (P) For some reason you can't check the filesystem of the script for nosuid. | |
752 | ||
753 | =item Can't coerce array into hash | |
754 | ||
755 | (F) You used an array where a hash was expected, but the array has no | |
756 | information on how to map from keys to array indices. You can do that | |
757 | only with arrays that have a hash reference at index 0. | |
758 | ||
759 | =item Can't goto subroutine from an eval-string | |
760 | ||
761 | (F) The "goto subroutine" call can't be used to jump out of an eval "string". | |
762 | (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.) | |
763 | ||
764 | =item Can't localize pseudo-hash element | |
765 | ||
766 | (F) You said something like C<< local $ar->{'key'} >>, where $ar is | |
767 | a reference to a pseudo-hash. That hasn't been implemented yet, but | |
768 | you can get a similar effect by localizing the corresponding array | |
769 | element directly -- C<< local $ar->[$ar->[0]{'key'}] >>. | |
770 | ||
771 | =item Can't use %%! because Errno.pm is not available | |
772 | ||
773 | (F) The first time the %! hash is used, perl automatically loads the | |
774 | Errno.pm module. The Errno module is expected to tie the %! hash to | |
775 | provide symbolic names for C<$!> errno values. | |
776 | ||
777 | =item Cannot find an opnumber for "%s" | |
778 | ||
779 | (F) A string of a form C<CORE::word> was given to prototype(), but | |
780 | there is no builtin with the name C<word>. | |
781 | ||
782 | =item Character class syntax [. .] is reserved for future extensions | |
783 | ||
784 | (W) Within regular expression character classes ([]) the syntax beginning | |
785 | with "[." and ending with ".]" is reserved for future extensions. | |
786 | If you need to represent those character sequences inside a regular | |
787 | expression character class, just quote the square brackets with the | |
788 | backslash: "\[." and ".\]". | |
789 | ||
790 | =item Character class syntax [: :] is reserved for future extensions | |
791 | ||
792 | (W) Within regular expression character classes ([]) the syntax beginning | |
793 | with "[:" and ending with ":]" is reserved for future extensions. | |
794 | If you need to represent those character sequences inside a regular | |
795 | expression character class, just quote the square brackets with the | |
796 | backslash: "\[:" and ":\]". | |
797 | ||
798 | =item Character class syntax [= =] is reserved for future extensions | |
799 | ||
800 | (W) Within regular expression character classes ([]) the syntax | |
801 | beginning with "[=" and ending with "=]" is reserved for future extensions. | |
802 | If you need to represent those character sequences inside a regular | |
803 | expression character class, just quote the square brackets with the | |
804 | backslash: "\[=" and "=\]". | |
805 | ||
806 | =item %s: Eval-group in insecure regular expression | |
807 | ||
808 | (F) Perl detected tainted data when trying to compile a regular expression | |
809 | that contains the C<(?{ ... })> zero-width assertion, which is unsafe. | |
810 | See L<perlre/(?{ code })>, and L<perlsec>. | |
811 | ||
812 | =item %s: Eval-group not allowed, use re 'eval' | |
813 | ||
814 | (F) A regular expression contained the C<(?{ ... })> zero-width assertion, | |
815 | but that construct is only allowed when the C<use re 'eval'> pragma is | |
816 | in effect. See L<perlre/(?{ code })>. | |
817 | ||
818 | =item %s: Eval-group not allowed at run time | |
819 | ||
820 | (F) Perl tried to compile a regular expression containing the C<(?{ ... })> | |
821 | zero-width assertion at run time, as it would when the pattern contains | |
822 | interpolated values. Since that is a security risk, it is not allowed. | |
823 | If you insist, you may still do this by explicitly building the pattern | |
824 | from an interpolated string at run time and using that in an eval(). | |
825 | See L<perlre/(?{ code })>. | |
826 | ||
827 | =item Explicit blessing to '' (assuming package main) | |
828 | ||
829 | (W) You are blessing a reference to a zero length string. This has | |
830 | the effect of blessing the reference into the package main. This is | |
831 | usually not what you want. Consider providing a default target | |
832 | package, e.g. bless($ref, $p || 'MyPackage'); | |
833 | ||
834 | =item Illegal hex digit ignored | |
835 | ||
836 | (W) You may have tried to use a character other than 0 - 9 or A - F in a | |
837 | hexadecimal number. Interpretation of the hexadecimal number stopped | |
838 | before the illegal character. | |
839 | ||
840 | =item No such array field | |
841 | ||
842 | (F) You tried to access an array as a hash, but the field name used is | |
843 | not defined. The hash at index 0 should map all valid field names to | |
844 | array indices for that to work. | |
845 | ||
846 | =item No such field "%s" in variable %s of type %s | |
847 | ||
848 | (F) You tried to access a field of a typed variable where the type | |
849 | does not know about the field name. The field names are looked up in | |
850 | the %FIELDS hash in the type package at compile time. The %FIELDS hash | |
851 | is usually set up with the 'fields' pragma. | |
852 | ||
853 | =item Out of memory during ridiculously large request | |
854 | ||
855 | (F) You can't allocate more than 2^31+"small amount" bytes. This error | |
856 | is most likely to be caused by a typo in the Perl program. e.g., C<$arr[time]> | |
857 | instead of C<$arr[$time]>. | |
858 | ||
859 | =item Range iterator outside integer range | |
860 | ||
861 | (F) One (or both) of the numeric arguments to the range operator ".." | |
862 | are outside the range which can be represented by integers internally. | |
863 | One possible workaround is to force Perl to use magical string | |
864 | increment by prepending "0" to your numbers. | |
865 | ||
866 | =item Recursive inheritance detected while looking for method '%s' %s | |
867 | ||
868 | (F) More than 100 levels of inheritance were encountered while invoking a | |
869 | method. Probably indicates an unintended loop in your inheritance hierarchy. | |
870 | ||
871 | =item Reference found where even-sized list expected | |
872 | ||
873 | (W) You gave a single reference where Perl was expecting a list with | |
874 | an even number of elements (for assignment to a hash). This | |
875 | usually means that you used the anon hash constructor when you meant | |
876 | to use parens. In any case, a hash requires key/value B<pairs>. | |
877 | ||
878 | %hash = { one => 1, two => 2, }; # WRONG | |
879 | %hash = [ qw/ an anon array / ]; # WRONG | |
880 | %hash = ( one => 1, two => 2, ); # right | |
881 | %hash = qw( one 1 two 2 ); # also fine | |
882 | ||
883 | =item Undefined value assigned to typeglob | |
884 | ||
885 | (W) An undefined value was assigned to a typeglob, a la C<*foo = undef>. | |
886 | This does nothing. It's possible that you really mean C<undef *foo>. | |
887 | ||
888 | =item Use of reserved word "%s" is deprecated | |
889 | ||
890 | (D) The indicated bareword is a reserved word. Future versions of perl | |
891 | may use it as a keyword, so you're better off either explicitly quoting | |
892 | the word in a manner appropriate for its context of use, or using a | |
893 | different name altogether. The warning can be suppressed for subroutine | |
894 | names by either adding a C<&> prefix, or using a package qualifier, | |
895 | e.g. C<&our()>, or C<Foo::our()>. | |
896 | ||
897 | =item perl: warning: Setting locale failed. | |
898 | ||
899 | (S) The whole warning message will look something like: | |
900 | ||
901 | perl: warning: Setting locale failed. | |
902 | perl: warning: Please check that your locale settings: | |
903 | LC_ALL = "En_US", | |
904 | LANG = (unset) | |
905 | are supported and installed on your system. | |
906 | perl: warning: Falling back to the standard locale ("C"). | |
907 | ||
908 | Exactly what were the failed locale settings varies. In the above the | |
909 | settings were that the LC_ALL was "En_US" and the LANG had no value. | |
910 | This error means that Perl detected that you and/or your system | |
911 | administrator have set up the so-called variable system but Perl could | |
912 | not use those settings. This was not dead serious, fortunately: there | |
913 | is a "default locale" called "C" that Perl can and will use, the | |
914 | script will be run. Before you really fix the problem, however, you | |
915 | will get the same error message each time you run Perl. How to really | |
916 | fix the problem can be found in L<perllocale/"LOCALE PROBLEMS">. | |
917 | ||
918 | =back | |
919 | ||
920 | ||
921 | =head1 Obsolete Diagnostics | |
922 | ||
923 | =over 4 | |
924 | ||
925 | =item Can't mktemp() | |
926 | ||
927 | (F) The mktemp() routine failed for some reason while trying to process | |
928 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. | |
929 | ||
930 | Removed because B<-e> doesn't use temporary files any more. | |
931 | ||
932 | =item Can't write to temp file for B<-e>: %s | |
933 | ||
934 | (F) The write routine failed for some reason while trying to process | |
935 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. | |
936 | ||
937 | Removed because B<-e> doesn't use temporary files any more. | |
938 | ||
939 | =item Cannot open temporary file | |
940 | ||
941 | (F) The create routine failed for some reason while trying to process | |
942 | a B<-e> switch. Maybe your /tmp partition is full, or clobbered. | |
943 | ||
944 | Removed because B<-e> doesn't use temporary files any more. | |
945 | ||
946 | =item regexp too big | |
947 | ||
948 | (F) The current implementation of regular expressions uses shorts as | |
949 | address offsets within a string. Unfortunately this means that if | |
950 | the regular expression compiles to longer than 32767, it'll blow up. | |
951 | Usually when you want a regular expression this big, there is a better | |
952 | way to do it with multiple statements. See L<perlre>. | |
953 | ||
954 | =back | |
955 | ||
956 | =head1 Configuration Changes | |
957 | ||
958 | You can use "Configure -Uinstallusrbinperl" which causes installperl | |
959 | to skip installing perl also as /usr/bin/perl. This is useful if you | |
960 | prefer not to modify /usr/bin for some reason or another but harmful | |
961 | because many scripts assume to find Perl in /usr/bin/perl. | |
962 | ||
963 | =head1 BUGS | |
964 | ||
965 | If you find what you think is a bug, you might check the headers of | |
966 | recently posted articles in the comp.lang.perl.misc newsgroup. | |
967 | There may also be information at http://www.perl.com/perl/ , the Perl | |
968 | Home Page. | |
969 | ||
970 | If you believe you have an unreported bug, please run the B<perlbug> | |
971 | program included with your release. Make sure you trim your bug down | |
972 | to a tiny but sufficient test case. Your bug report, along with the | |
973 | output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be | |
974 | analysed by the Perl porting team. | |
975 | ||
976 | =head1 SEE ALSO | |
977 | ||
978 | The F<Changes> file for exhaustive details on what changed. | |
979 | ||
980 | The F<INSTALL> file for how to build Perl. | |
981 | ||
982 | The F<README> file for general stuff. | |
983 | ||
984 | The F<Artistic> and F<Copying> files for copyright information. | |
985 | ||
986 | =head1 HISTORY | |
987 | ||
988 | Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many contributions | |
989 | from The Perl Porters. | |
990 | ||
991 | Send omissions or corrections to <F<perlbug@perl.com>>. | |
992 | ||
993 | =cut |