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f6eae373 RGS |
1 | =head1 NAME |
2 | ||
3 | perldelta - what is new for perl v5.9.5 | |
4 | ||
5 | =head1 DESCRIPTION | |
6 | ||
7 | This document describes differences between the 5.9.4 and the 5.9.5 | |
8 | development releases. See L<perl590delta>, L<perl591delta>, | |
9 | L<perl592delta>, L<perl593delta> and L<perl594delta> for the differences | |
10 | between 5.8.0 and 5.9.4. | |
11 | ||
12 | =head1 Incompatible Changes | |
13 | ||
20ee07fb RGS |
14 | =head2 Tainting and printf |
15 | ||
16 | When perl is run under taint mode, C<printf()> and C<sprintf()> will now | |
3f10c77a | 17 | reject any tainted format argument. (Rafael Garcia-Suarez) |
20ee07fb | 18 | |
54a37cc6 RGS |
19 | =head2 undef and signal handlers |
20 | ||
21 | Undefining or deleting a signal handler via C<undef $SIG{FOO}> is now | |
97f820fb RGS |
22 | equivalent to setting it to C<'DEFAULT'>. (Rafael) |
23 | ||
24 | =head2 strictures and array/hash dereferencing in defined() | |
25 | ||
26 | C<defined @$foo> and C<defined %$bar> are now subject to C<strict 'refs'> | |
27 | (that is, C<$foo> and C<$bar> shall be proper references there.) | |
28 | (Nicholas Clark) | |
29 | ||
30 | (However, C<defined(@foo)> and C<defined(%bar)> are discouraged constructs | |
31 | anyway.) | |
54a37cc6 | 32 | |
74bb26f2 RGS |
33 | =head2 C<(?p{})> has been removed |
34 | ||
35 | The regular expression construct C<(?p{})>, which was deprecated in perl | |
36 | 5.8, has been removed. Use C<(??{})> instead. (Rafael) | |
37 | ||
73966613 RGS |
38 | =head2 Removal of the bytecode compiler and of perlcc |
39 | ||
40 | C<perlcc>, the byteloader and the supporting modules (B::C, B::CC, | |
41 | B::Bytecode, etc.) are no longer distributed with the perl sources. Those | |
42 | experimental tools have never worked reliably, and, due to the lack of | |
43 | volunteers to keep them in line with the perl interpreter developments, it | |
44 | was decided to remove them instead of shipping a broken version of those. | |
45 | The last version of those modules can be found with perl 5.9.4. | |
46 | ||
47 | However the B compiler framework stays supported in the perl core, as with | |
48 | the more useful modules it has permitted (among others, B::Deparse and | |
49 | B::Concise). | |
50 | ||
51 | =head2 Removal of the JPL | |
52 | ||
53 | The JPL (Java-Perl Linguo) has been removed from the perl sources tarball. | |
54 | ||
afa2ea4a RGS |
55 | =head2 Recursive inheritance detected earlier |
56 | ||
57 | Perl will now immediately throw an exception if you modify any package's | |
58 | C<@ISA> in such a way that it would cause recursive inheritance. | |
59 | ||
60 | Previously, the exception would not occur until Perl attempted to make | |
61 | use of the recursive inheritance while resolving a method or doing a | |
62 | C<$foo-E<gt>isa($bar)> lookup. | |
63 | ||
f6eae373 RGS |
64 | =head1 Core Enhancements |
65 | ||
072f65b4 RGS |
66 | =head2 Regular expressions |
67 | ||
68 | =over 4 | |
69 | ||
70 | =item Recursive Patterns | |
71 | ||
72 | It is now possible to write recursive patterns without using the C<(??{})> | |
73 | construct. This new way is more efficient, and in many cases easier to | |
74 | read. | |
75 | ||
76 | Each capturing parenthesis can now be treated as an independent pattern | |
77 | that can be entered by using the C<(?PARNO)> syntax (C<PARNO> standing for | |
78 | "parenthesis number"). For example, the following pattern will match | |
79 | nested balanced angle brackets: | |
80 | ||
81 | / | |
82 | ^ # start of line | |
83 | ( # start capture buffer 1 | |
84 | < # match an opening angle bracket | |
85 | (?: # match one of: | |
86 | (?> # don't backtrack over the inside of this group | |
87 | [^<>]+ # one or more non angle brackets | |
88 | ) # end non backtracking group | |
89 | | # ... or ... | |
90 | (?1) # recurse to bracket 1 and try it again | |
91 | )* # 0 or more times. | |
92 | > # match a closing angle bracket | |
93 | ) # end capture buffer one | |
94 | $ # end of line | |
95 | /x | |
96 | ||
97 | Note, users experienced with PCRE will find that the Perl implementation | |
98 | of this feature differs from the PCRE one in that it is possible to | |
99 | backtrack into a recursed pattern, whereas in PCRE the recursion is | |
73966613 | 100 | atomic or "possessive" in nature. (Yves Orton) |
072f65b4 RGS |
101 | |
102 | =item Named Capture Buffers | |
103 | ||
104 | It is now possible to name capturing parenthesis in a pattern and refer to | |
105 | the captured contents by name. The naming syntax is C<< (?<NAME>....) >>. | |
106 | It's possible to backreference to a named buffer with the C<< \k<NAME> >> | |
97f820fb RGS |
107 | syntax. In code, the new magical hashes C<%+> and C<%-> can be used to |
108 | access the contents of the capture buffers. | |
072f65b4 RGS |
109 | |
110 | Thus, to replace all doubled chars, one could write | |
111 | ||
112 | s/(?<letter>.)\k<letter>/$+{letter}/g | |
113 | ||
97f820fb | 114 | Only buffers with defined contents will be "visible" in the C<%+> hash, so |
072f65b4 RGS |
115 | it's possible to do something like |
116 | ||
117 | foreach my $name (keys %+) { | |
118 | print "content of buffer '$name' is $+{$name}\n"; | |
119 | } | |
120 | ||
97f820fb RGS |
121 | The C<%-> hash is a bit more complete, since it will contain array refs |
122 | holding values from all capture buffers similarly named, if there should | |
123 | be many of them. | |
124 | ||
125 | C<%+> and C<%-> are implemented as tied hashes through the new module | |
80305961 | 126 | C<Tie::Hash::NamedCapture>. |
97f820fb | 127 | |
072f65b4 RGS |
128 | Users exposed to the .NET regex engine will find that the perl |
129 | implementation differs in that the numerical ordering of the buffers | |
130 | is sequential, and not "unnamed first, then named". Thus in the pattern | |
131 | ||
132 | /(A)(?<B>B)(C)(?<D>D)/ | |
133 | ||
134 | $1 will be 'A', $2 will be 'B', $3 will be 'C' and $4 will be 'D' and not | |
135 | $1 is 'A', $2 is 'C' and $3 is 'B' and $4 is 'D' that a .NET programmer | |
73966613 | 136 | would expect. This is considered a feature. :-) (Yves Orton) |
072f65b4 | 137 | |
b9b4dddf YO |
138 | =item Possessive Quantifiers |
139 | ||
ee9b8eae | 140 | Perl now supports the "possessive quantifier" syntax of the "atomic match" |
b9b4dddf | 141 | pattern. Basically a possessive quantifier matches as much as it can and never |
ee9b8eae | 142 | gives any back. Thus it can be used to control backtracking. The syntax is |
b9b4dddf YO |
143 | similar to non-greedy matching, except instead of using a '?' as the modifier |
144 | the '+' is used. Thus C<?+>, C<*+>, C<++>, C<{min,max}+> are now legal | |
73966613 | 145 | quantifiers. (Yves Orton) |
b9b4dddf | 146 | |
24b23f37 YO |
147 | =item Backtracking control verbs |
148 | ||
3f10c77a | 149 | The regex engine now supports a number of special-purpose backtrack |
5d458dd8 | 150 | control verbs: (*THEN), (*PRUNE), (*MARK), (*SKIP), (*COMMIT), (*FAIL) |
c74340f9 YO |
151 | and (*ACCEPT). See L<perlre> for their descriptions. (Yves Orton) |
152 | ||
153 | =item Relative backreferences | |
154 | ||
2bf803e2 YO |
155 | A new syntax C<\g{N}> or C<\gN> where "N" is a decimal integer allows a |
156 | safer form of back-reference notation as well as allowing relative | |
157 | backreferences. This should make it easier to generate and embed patterns | |
3f10c77a | 158 | that contain backreferences. See L<perlre/"Capture buffers">. (Yves Orton) |
24b23f37 | 159 | |
97f820fb | 160 | =item C<\K> escape |
ee9b8eae YO |
161 | |
162 | The functionality of Jeff Pinyan's module Regexp::Keep has been added to | |
163 | the core. You can now use in regular expressions the special escape C<\K> | |
164 | as a way to do something like floating length positive lookbehind. It is | |
165 | also useful in substitutions like: | |
166 | ||
167 | s/(foo)bar/$1/g | |
168 | ||
169 | that can now be converted to | |
170 | ||
171 | s/foo\Kbar//g | |
172 | ||
97f820fb | 173 | which is much more efficient. (Yves Orton) |
ee9b8eae | 174 | |
41b9272f RGS |
175 | =item Vertical and horizontal whitespace, and linebreak |
176 | ||
177 | Regular expressions now recognize the C<\v> and C<\h> escapes, that match | |
178 | vertical and horizontal whitespace, respectively. C<\V> and C<\H> | |
179 | logically match their complements. | |
180 | ||
329d35d1 | 181 | C<\R> matches a generic linebreak, that is, vertical whitespace, plus |
41b9272f RGS |
182 | the multi-character sequence C<"\x0D\x0A">. |
183 | ||
75c442e4 NC |
184 | =back |
185 | ||
d5494b07 RGS |
186 | =head2 The C<_> prototype |
187 | ||
188 | A new prototype character has been added. C<_> is equivalent to C<$> (it | |
189 | denotes a scalar), but defaults to C<$_> if the corresponding argument | |
190 | isn't supplied. Due to the optional nature of the argument, you can only | |
191 | use it at the end of a prototype, or before a semicolon. | |
192 | ||
73966613 RGS |
193 | This has a small incompatible consequence: the prototype() function has |
194 | been adjusted to return C<_> for some built-ins in appropriate cases (for | |
97f820fb | 195 | example, C<prototype('CORE::rmdir')>). (Rafael) |
73966613 | 196 | |
49f595a6 RGS |
197 | =head2 UNITCHECK blocks |
198 | ||
199 | C<UNITCHECK>, a new special code block has been introduced, in addition to | |
200 | C<BEGIN>, C<CHECK>, C<INIT> and C<END>. | |
201 | ||
202 | C<CHECK> and C<INIT> blocks, while useful for some specialized purposes, | |
203 | are always executed at the transition between the compilation and the | |
204 | execution of the main program, and thus are useless whenever code is | |
205 | loaded at runtime. On the other hand, C<UNITCHECK> blocks are executed | |
206 | just after the unit which defined them has been compiled. See L<perlmod> | |
207 | for more information. (Alex Gough) | |
208 | ||
5a093634 RGS |
209 | =head2 readpipe() is now overridable |
210 | ||
211 | The built-in function readpipe() is now overridable. Overriding it permits | |
74bb26f2 RGS |
212 | also to override its operator counterpart, C<qx//> (a.k.a. C<``>). |
213 | Moreover, it now defaults to C<$_> if no argument is provided. (Rafael) | |
214 | ||
215 | =head2 default argument for readline() | |
216 | ||
217 | readline() now defaults to C<*ARGV> if no argument is provided. (Rafael) | |
5a093634 | 218 | |
73966613 RGS |
219 | =head2 UCD 5.0.0 |
220 | ||
221 | The copy of the Unicode Character Database included in Perl 5.9 has | |
222 | been updated to version 5.0.0. | |
223 | ||
97f820fb RGS |
224 | =head2 Smart match |
225 | ||
226 | The smart match operator (C<~~>) is now available by default (you don't | |
227 | need to enable it with C<use feature> any longer). (Michael G Schwern) | |
228 | ||
74bb26f2 RGS |
229 | =head2 Implicit loading of C<feature> |
230 | ||
231 | The C<feature> pragma is now implicitly loaded when you require a minimal | |
232 | perl version (with the C<use VERSION> construct) greater than, or equal | |
233 | to, 5.9.5. | |
234 | ||
f6eae373 RGS |
235 | =head1 Modules and Pragmas |
236 | ||
74bb26f2 RGS |
237 | =head2 New Pragma, C<mro> |
238 | ||
239 | A new pragma, C<mro> (for Method Resolution Order) has been added. It | |
240 | permits to switch, on a per-class basis, the algorithm that perl uses to | |
241 | find inherited methods in case of a mutiple inheritance hierachy. The | |
242 | default MRO hasn't changed (DFS, for Depth First Search). Another MRO is | |
243 | available: the C3 algorithm. See L<mro> for more information. | |
244 | (Brandon Black) | |
245 | ||
3284ac36 RGS |
246 | =head2 bignum, bigint, bigrat |
247 | ||
248 | The three numeric pragmas C<bignum>, C<bigint> and C<bigrat> are now | |
249 | lexically scoped. (Tels) | |
250 | ||
f6eae373 RGS |
251 | =head2 New Core Modules |
252 | ||
73966613 RGS |
253 | =over 4 |
254 | ||
255 | =item * | |
256 | ||
257 | C<Locale::Maketext::Simple>, needed by CPANPLUS, is a simple wrapper around | |
258 | C<Locale::Maketext::Lexicon>. Note that C<Locale::Maketext::Lexicon> isn't | |
259 | included in the perl core; the behaviour of C<Locale::Maketext::Simple> | |
260 | gracefully degrades when the later isn't present. | |
261 | ||
262 | =item * | |
263 | ||
264 | C<Params::Check> implements a generic input parsing/checking mechanism. It | |
265 | is used by CPANPLUS. | |
266 | ||
5a093634 RGS |
267 | =item * |
268 | ||
269 | C<Term::UI> simplifies the task to ask questions at a terminal prompt. | |
270 | ||
271 | =item * | |
272 | ||
273 | C<Object::Accessor> provides an interface to create per-object accessors. | |
274 | ||
97f820fb RGS |
275 | =item * |
276 | ||
277 | C<Module::Pluggable> is a simple framework to create modules that accept | |
278 | pluggable sub-modules. | |
279 | ||
280 | =item * | |
281 | ||
282 | C<Module::Load::Conditional> provides simple ways to query and possibly | |
283 | load installed modules. | |
284 | ||
285 | =item * | |
286 | ||
287 | C<Time::Piece> provides an object oriented interface to time functions, | |
288 | overriding the built-ins localtime() and gmtime(). | |
289 | ||
290 | =item * | |
291 | ||
292 | C<IPC::Cmd> helps to find and run external commands, possibly | |
293 | interactively. | |
294 | ||
295 | =item * | |
296 | ||
297 | C<File::Fetch> provide a simple generic file fetching mechanism. | |
298 | ||
299 | =item * | |
300 | ||
301 | C<Archive::Extract> is a generic archive extraction mechanism | |
302 | for F<.tar> (plain, gziped or bzipped) or F<.zip> files. | |
303 | ||
74bb26f2 RGS |
304 | =item * |
305 | ||
306 | C<CPANPLUS> provides an API and a command-line tool to access the CPAN | |
307 | mirrors. | |
308 | ||
73966613 RGS |
309 | =back |
310 | ||
d5494b07 RGS |
311 | =head2 Module changes |
312 | ||
313 | =over 4 | |
314 | ||
ddf4dafe RGS |
315 | =item C<assertions> |
316 | ||
317 | The C<assertions> pragma, its submodules C<assertions::activate> and | |
318 | C<assertions::compat> and the B<-A> command-line switch have been removed. | |
319 | The interface was not judged mature enough for inclusion in a stable | |
320 | release. | |
321 | ||
d5494b07 RGS |
322 | =item C<base> |
323 | ||
324 | The C<base> pragma now warns if a class tries to inherit from itself. | |
97f820fb | 325 | (Curtis "Ovid" Poe) |
d5494b07 | 326 | |
74bb26f2 RGS |
327 | =item C<strict> and C<warnings> |
328 | ||
329 | C<strict> and C<warnings> will now complain loudly if they are loaded via | |
330 | incorrect casing (as in C<use Strict;>). (Johan Vromans) | |
331 | ||
18857c0b RGS |
332 | =item C<warnings> |
333 | ||
334 | The C<warnings> pragma doesn't load C<Carp> anymore. That means that code | |
335 | that used C<Carp> routines without having loaded it at compile time might | |
336 | need to be adjusted; typically, the following (faulty) code won't work | |
337 | anymore, and will require parentheses to be added after the function name: | |
338 | ||
339 | use warnings; | |
340 | require Carp; | |
341 | Carp::confess "argh"; | |
342 | ||
97f820fb RGS |
343 | =item C<less> |
344 | ||
345 | C<less> now does something useful (or at least it tries to). In fact, it | |
346 | has been turned into a lexical pragma. So, in your modules, you can now | |
347 | test whether your users have requested to use less CPU, or less memory, | |
348 | less magic, or maybe even less fat. See L<less> for more. (Joshua ben | |
349 | Jore) | |
350 | ||
3f10c77a RGS |
351 | =item C<Attribute::Handlers> |
352 | ||
353 | C<Attribute::Handlers> can now report the caller's file and line number. | |
354 | (David Feldman) | |
355 | ||
97f820fb RGS |
356 | =item C<B::Lint> |
357 | ||
358 | C<B::Lint> is now based on C<Module::Pluggable>, and so can be extended | |
359 | with plugins. (Joshua ben Jore) | |
360 | ||
361 | =item C<B> | |
362 | ||
363 | It's now possible to access the lexical pragma hints (C<%^H>) by using the | |
364 | method B::COP::hints_hash(). It returns a C<B::RHE> object, which in turn | |
365 | can be used to get a hash reference via the method B::RHE::HASH(). (Joshua | |
366 | ben Jore) | |
367 | ||
368 | =for p5p XXX document this in B.pm too | |
369 | ||
ab4e6221 RGS |
370 | =item C<Thread> |
371 | ||
372 | As the old 5005thread threading model has been removed, in favor of the | |
373 | ithreads scheme, the C<Thread> module is now a compatibility wrapper, to | |
374 | be used in old code only. | |
375 | ||
d5494b07 RGS |
376 | =back |
377 | ||
f6eae373 RGS |
378 | =head1 Utility Changes |
379 | ||
74bb26f2 RGS |
380 | =head2 C<cpanp> |
381 | ||
382 | C<cpanp>, the CPANPLUS shell, has been added. (C<cpanp-run-perl>, an | |
383 | helper for CPANPLUS operation, has been added too, but isn't intended for | |
384 | direct use). | |
385 | ||
8a499140 RGS |
386 | =head2 C<cpan2dist> |
387 | ||
388 | C<cpan2dist> is a new utility, that comes with CPANPLUS. It's a tool to | |
389 | create distributions (or packages) from CPAN modules. | |
390 | ||
74bb26f2 RGS |
391 | =head2 C<pod2html> |
392 | ||
393 | The output of C<pod2html> has been enhanced to be more customizable via | |
394 | CSS. Some formatting problems were also corrected. (Jari Aalto) | |
395 | ||
f6eae373 RGS |
396 | =head1 Documentation |
397 | ||
74bb26f2 RGS |
398 | =head2 New manpage, perlunifaq |
399 | ||
400 | A new manual page, L<perlunifaq> (the Perl Unicode FAQ), has been added | |
401 | (Juerd Waalboer). | |
402 | ||
f6eae373 RGS |
403 | =head1 Performance Enhancements |
404 | ||
405 | =head1 Installation and Configuration Improvements | |
406 | ||
73966613 RGS |
407 | =head2 C++ compatibility |
408 | ||
409 | Efforts have been made to make perl and the core XS modules compilable | |
410 | with various C++ compilers (although the situation is not perfect with | |
411 | some of the compilers on some of the platforms tested.) | |
412 | ||
ab4e6221 RGS |
413 | =head2 Visual C++ |
414 | ||
415 | Perl now can be compiled with Microsoft Visual C++ 2005. | |
416 | ||
3f10c77a RGS |
417 | =head2 Static build on Win32 |
418 | ||
419 | It's now possible to build a C<perl-static.exe> that doesn't depend | |
420 | on C<perl59.dll> on Win32. See the Win32 makefiles for details. | |
e3c82801 | 421 | (Vadim Konovalov) |
3f10c77a | 422 | |
ab4e6221 RGS |
423 | =head2 C<d_pseudofork> |
424 | ||
425 | A new configuration variable, available as C<$Config{d_pseudofork}> in | |
426 | the L<Config> module, has been added, to distinguish real fork() support | |
427 | from fake pseudofork used on Windows platforms. | |
428 | ||
73966613 RGS |
429 | =head2 Ports |
430 | ||
431 | Perl has been reported to work on MidnightBSD. | |
432 | ||
f6eae373 RGS |
433 | =head1 Selected Bug Fixes |
434 | ||
49f595a6 RGS |
435 | PerlIO::scalar will now prevent writing to read-only scalars. Moreover, |
436 | seek() is now supported with PerlIO::scalar-based filehandles, the | |
97f820fb | 437 | underlying string being zero-filled as needed. (Rafael, Jarkko Hietaniemi) |
73966613 RGS |
438 | |
439 | study() never worked for UTF-8 strings, but could lead to false results. | |
440 | It's now a no-op on UTF-8 data. (Yves Orton) | |
441 | ||
49f595a6 RGS |
442 | The signals SIGILL, SIGBUS and SIGSEGV are now always delivered in an |
443 | "unsafe" manner (contrary to other signals, that are deferred until the | |
444 | perl interpreter reaches a reasonably stable state; see | |
97f820fb | 445 | L<perlipc/"Deferred Signals (Safe Signals)">). (Rafael) |
49f595a6 | 446 | |
5a093634 RGS |
447 | When a module or a file is loaded through an @INC-hook, and when this hook |
448 | has set a filename entry in %INC, __FILE__ is now set for this module | |
97f820fb RGS |
449 | accordingly to the contents of that %INC entry. (Rafael) |
450 | ||
451 | The C<-w> and C<-t> switches can now be used together without messing | |
452 | up what categories of warnings are activated or not. (Rafael) | |
5a093634 | 453 | |
74bb26f2 RGS |
454 | Duping a filehandle which has the C<:utf8> PerlIO layer set will now |
455 | properly carry that layer on the duped filehandle. (Rafael) | |
456 | ||
37a7450d | 457 | Localizing an hash element whose key was given as a variable didn't work |
21e0a455 RGS |
458 | correctly if the variable was changed while the local() was in effect (as |
459 | in C<local $h{$x}; ++$x>). (Bo Lindbergh) | |
37a7450d | 460 | |
f6eae373 RGS |
461 | =head1 New or Changed Diagnostics |
462 | ||
74bb26f2 RGS |
463 | =head2 Deprecations |
464 | ||
465 | Two deprecation warnings have been added: (Rafael) | |
466 | ||
467 | Opening dirhandle %s also as a file | |
468 | Opening filehandle %s also as a directory | |
469 | ||
f6eae373 RGS |
470 | =head1 Changed Internals |
471 | ||
73966613 RGS |
472 | The anonymous hash and array constructors now take 1 op in the optree |
473 | instead of 3, now that pp_anonhash and pp_anonlist return a reference to | |
474 | an hash/array when the op is flagged with OPf_SPECIAL (Nicholas Clark). | |
475 | ||
97f820fb RGS |
476 | =for p5p XXX have we some docs on how to create regexp engine plugins, since that's now possible ? (perlreguts) |
477 | ||
478 | =for p5p XXX new BIND SV type, #29544, #29642 | |
479 | ||
f6eae373 RGS |
480 | =head1 Known Problems |
481 | ||
482 | =head2 Platform Specific Problems | |
483 | ||
484 | =head1 Reporting Bugs | |
485 | ||
486 | If you find what you think is a bug, you might check the articles | |
487 | recently posted to the comp.lang.perl.misc newsgroup and the perl | |
488 | bug database at http://rt.perl.org/rt3/ . There may also be | |
489 | information at http://www.perl.org/ , the Perl Home Page. | |
490 | ||
491 | If you believe you have an unreported bug, please run the B<perlbug> | |
492 | program included with your release. Be sure to trim your bug down | |
493 | to a tiny but sufficient test case. Your bug report, along with the | |
494 | output of C<perl -V>, will be sent off to perlbug@perl.org to be | |
495 | analysed by the Perl porting team. | |
496 | ||
497 | =head1 SEE ALSO | |
498 | ||
499 | The F<Changes> file for exhaustive details on what changed. | |
500 | ||
501 | The F<INSTALL> file for how to build Perl. | |
502 | ||
503 | The F<README> file for general stuff. | |
504 | ||
505 | The F<Artistic> and F<Copying> files for copyright information. | |
506 | ||
507 | =cut |