Commit | Line | Data |
---|---|---|
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 | |
73966613 RGS |
33 | =head2 Removal of the bytecode compiler and of perlcc |
34 | ||
35 | C<perlcc>, the byteloader and the supporting modules (B::C, B::CC, | |
36 | B::Bytecode, etc.) are no longer distributed with the perl sources. Those | |
37 | experimental tools have never worked reliably, and, due to the lack of | |
38 | volunteers to keep them in line with the perl interpreter developments, it | |
39 | was decided to remove them instead of shipping a broken version of those. | |
40 | The last version of those modules can be found with perl 5.9.4. | |
41 | ||
42 | However the B compiler framework stays supported in the perl core, as with | |
43 | the more useful modules it has permitted (among others, B::Deparse and | |
44 | B::Concise). | |
45 | ||
46 | =head2 Removal of the JPL | |
47 | ||
48 | The JPL (Java-Perl Linguo) has been removed from the perl sources tarball. | |
49 | ||
f6eae373 RGS |
50 | =head1 Core Enhancements |
51 | ||
072f65b4 RGS |
52 | =head2 Regular expressions |
53 | ||
54 | =over 4 | |
55 | ||
56 | =item Recursive Patterns | |
57 | ||
58 | It is now possible to write recursive patterns without using the C<(??{})> | |
59 | construct. This new way is more efficient, and in many cases easier to | |
60 | read. | |
61 | ||
62 | Each capturing parenthesis can now be treated as an independent pattern | |
63 | that can be entered by using the C<(?PARNO)> syntax (C<PARNO> standing for | |
64 | "parenthesis number"). For example, the following pattern will match | |
65 | nested balanced angle brackets: | |
66 | ||
67 | / | |
68 | ^ # start of line | |
69 | ( # start capture buffer 1 | |
70 | < # match an opening angle bracket | |
71 | (?: # match one of: | |
72 | (?> # don't backtrack over the inside of this group | |
73 | [^<>]+ # one or more non angle brackets | |
74 | ) # end non backtracking group | |
75 | | # ... or ... | |
76 | (?1) # recurse to bracket 1 and try it again | |
77 | )* # 0 or more times. | |
78 | > # match a closing angle bracket | |
79 | ) # end capture buffer one | |
80 | $ # end of line | |
81 | /x | |
82 | ||
83 | Note, users experienced with PCRE will find that the Perl implementation | |
84 | of this feature differs from the PCRE one in that it is possible to | |
85 | backtrack into a recursed pattern, whereas in PCRE the recursion is | |
73966613 | 86 | atomic or "possessive" in nature. (Yves Orton) |
072f65b4 RGS |
87 | |
88 | =item Named Capture Buffers | |
89 | ||
90 | It is now possible to name capturing parenthesis in a pattern and refer to | |
91 | the captured contents by name. The naming syntax is C<< (?<NAME>....) >>. | |
92 | It's possible to backreference to a named buffer with the C<< \k<NAME> >> | |
97f820fb RGS |
93 | syntax. In code, the new magical hashes C<%+> and C<%-> can be used to |
94 | access the contents of the capture buffers. | |
072f65b4 RGS |
95 | |
96 | Thus, to replace all doubled chars, one could write | |
97 | ||
98 | s/(?<letter>.)\k<letter>/$+{letter}/g | |
99 | ||
97f820fb | 100 | Only buffers with defined contents will be "visible" in the C<%+> hash, so |
072f65b4 RGS |
101 | it's possible to do something like |
102 | ||
103 | foreach my $name (keys %+) { | |
104 | print "content of buffer '$name' is $+{$name}\n"; | |
105 | } | |
106 | ||
97f820fb RGS |
107 | The C<%-> hash is a bit more complete, since it will contain array refs |
108 | holding values from all capture buffers similarly named, if there should | |
109 | be many of them. | |
110 | ||
111 | C<%+> and C<%-> are implemented as tied hashes through the new module | |
112 | C<re::Tie::Hash::NamedCapture>. | |
113 | ||
072f65b4 RGS |
114 | Users exposed to the .NET regex engine will find that the perl |
115 | implementation differs in that the numerical ordering of the buffers | |
116 | is sequential, and not "unnamed first, then named". Thus in the pattern | |
117 | ||
118 | /(A)(?<B>B)(C)(?<D>D)/ | |
119 | ||
120 | $1 will be 'A', $2 will be 'B', $3 will be 'C' and $4 will be 'D' and not | |
121 | $1 is 'A', $2 is 'C' and $3 is 'B' and $4 is 'D' that a .NET programmer | |
73966613 | 122 | would expect. This is considered a feature. :-) (Yves Orton) |
072f65b4 | 123 | |
b9b4dddf YO |
124 | =item Possessive Quantifiers |
125 | ||
ee9b8eae | 126 | Perl now supports the "possessive quantifier" syntax of the "atomic match" |
b9b4dddf | 127 | pattern. Basically a possessive quantifier matches as much as it can and never |
ee9b8eae | 128 | gives any back. Thus it can be used to control backtracking. The syntax is |
b9b4dddf YO |
129 | similar to non-greedy matching, except instead of using a '?' as the modifier |
130 | the '+' is used. Thus C<?+>, C<*+>, C<++>, C<{min,max}+> are now legal | |
73966613 | 131 | quantifiers. (Yves Orton) |
b9b4dddf | 132 | |
24b23f37 YO |
133 | =item Backtracking control verbs |
134 | ||
3f10c77a | 135 | The regex engine now supports a number of special-purpose backtrack |
5d458dd8 | 136 | control verbs: (*THEN), (*PRUNE), (*MARK), (*SKIP), (*COMMIT), (*FAIL) |
c74340f9 YO |
137 | and (*ACCEPT). See L<perlre> for their descriptions. (Yves Orton) |
138 | ||
139 | =item Relative backreferences | |
140 | ||
2bf803e2 YO |
141 | A new syntax C<\g{N}> or C<\gN> where "N" is a decimal integer allows a |
142 | safer form of back-reference notation as well as allowing relative | |
143 | backreferences. This should make it easier to generate and embed patterns | |
3f10c77a | 144 | that contain backreferences. See L<perlre/"Capture buffers">. (Yves Orton) |
24b23f37 | 145 | |
97f820fb | 146 | =item C<\K> escape |
ee9b8eae YO |
147 | |
148 | The functionality of Jeff Pinyan's module Regexp::Keep has been added to | |
149 | the core. You can now use in regular expressions the special escape C<\K> | |
150 | as a way to do something like floating length positive lookbehind. It is | |
151 | also useful in substitutions like: | |
152 | ||
153 | s/(foo)bar/$1/g | |
154 | ||
155 | that can now be converted to | |
156 | ||
157 | s/foo\Kbar//g | |
158 | ||
97f820fb | 159 | which is much more efficient. (Yves Orton) |
ee9b8eae | 160 | |
75c442e4 NC |
161 | =back |
162 | ||
d5494b07 RGS |
163 | =head2 The C<_> prototype |
164 | ||
165 | A new prototype character has been added. C<_> is equivalent to C<$> (it | |
166 | denotes a scalar), but defaults to C<$_> if the corresponding argument | |
167 | isn't supplied. Due to the optional nature of the argument, you can only | |
168 | use it at the end of a prototype, or before a semicolon. | |
169 | ||
73966613 RGS |
170 | This has a small incompatible consequence: the prototype() function has |
171 | been adjusted to return C<_> for some built-ins in appropriate cases (for | |
97f820fb | 172 | example, C<prototype('CORE::rmdir')>). (Rafael) |
73966613 | 173 | |
49f595a6 RGS |
174 | =head2 UNITCHECK blocks |
175 | ||
176 | C<UNITCHECK>, a new special code block has been introduced, in addition to | |
177 | C<BEGIN>, C<CHECK>, C<INIT> and C<END>. | |
178 | ||
179 | C<CHECK> and C<INIT> blocks, while useful for some specialized purposes, | |
180 | are always executed at the transition between the compilation and the | |
181 | execution of the main program, and thus are useless whenever code is | |
182 | loaded at runtime. On the other hand, C<UNITCHECK> blocks are executed | |
183 | just after the unit which defined them has been compiled. See L<perlmod> | |
184 | for more information. (Alex Gough) | |
185 | ||
5a093634 RGS |
186 | =head2 readpipe() is now overridable |
187 | ||
188 | The built-in function readpipe() is now overridable. Overriding it permits | |
97f820fb | 189 | also to override its operator counterpart, C<qx//> (a.k.a. C<``>). (Rafael) |
5a093634 | 190 | |
73966613 RGS |
191 | =head2 UCD 5.0.0 |
192 | ||
193 | The copy of the Unicode Character Database included in Perl 5.9 has | |
194 | been updated to version 5.0.0. | |
195 | ||
97f820fb RGS |
196 | =head2 Smart match |
197 | ||
198 | The smart match operator (C<~~>) is now available by default (you don't | |
199 | need to enable it with C<use feature> any longer). (Michael G Schwern) | |
200 | ||
f6eae373 RGS |
201 | =head1 Modules and Pragmas |
202 | ||
203 | =head2 New Core Modules | |
204 | ||
73966613 RGS |
205 | =over 4 |
206 | ||
207 | =item * | |
208 | ||
209 | C<Locale::Maketext::Simple>, needed by CPANPLUS, is a simple wrapper around | |
210 | C<Locale::Maketext::Lexicon>. Note that C<Locale::Maketext::Lexicon> isn't | |
211 | included in the perl core; the behaviour of C<Locale::Maketext::Simple> | |
212 | gracefully degrades when the later isn't present. | |
213 | ||
214 | =item * | |
215 | ||
216 | C<Params::Check> implements a generic input parsing/checking mechanism. It | |
217 | is used by CPANPLUS. | |
218 | ||
5a093634 RGS |
219 | =item * |
220 | ||
221 | C<Term::UI> simplifies the task to ask questions at a terminal prompt. | |
222 | ||
223 | =item * | |
224 | ||
225 | C<Object::Accessor> provides an interface to create per-object accessors. | |
226 | ||
97f820fb RGS |
227 | =item * |
228 | ||
229 | C<Module::Pluggable> is a simple framework to create modules that accept | |
230 | pluggable sub-modules. | |
231 | ||
232 | =item * | |
233 | ||
234 | C<Module::Load::Conditional> provides simple ways to query and possibly | |
235 | load installed modules. | |
236 | ||
237 | =item * | |
238 | ||
239 | C<Time::Piece> provides an object oriented interface to time functions, | |
240 | overriding the built-ins localtime() and gmtime(). | |
241 | ||
242 | =item * | |
243 | ||
244 | C<IPC::Cmd> helps to find and run external commands, possibly | |
245 | interactively. | |
246 | ||
247 | =item * | |
248 | ||
249 | C<File::Fetch> provide a simple generic file fetching mechanism. | |
250 | ||
251 | =item * | |
252 | ||
253 | C<Archive::Extract> is a generic archive extraction mechanism | |
254 | for F<.tar> (plain, gziped or bzipped) or F<.zip> files. | |
255 | ||
73966613 RGS |
256 | =back |
257 | ||
d5494b07 RGS |
258 | =head2 Module changes |
259 | ||
260 | =over 4 | |
261 | ||
262 | =item C<base> | |
263 | ||
264 | The C<base> pragma now warns if a class tries to inherit from itself. | |
97f820fb | 265 | (Curtis "Ovid" Poe) |
d5494b07 | 266 | |
18857c0b RGS |
267 | =item C<warnings> |
268 | ||
269 | The C<warnings> pragma doesn't load C<Carp> anymore. That means that code | |
270 | that used C<Carp> routines without having loaded it at compile time might | |
271 | need to be adjusted; typically, the following (faulty) code won't work | |
272 | anymore, and will require parentheses to be added after the function name: | |
273 | ||
274 | use warnings; | |
275 | require Carp; | |
276 | Carp::confess "argh"; | |
277 | ||
97f820fb RGS |
278 | =item C<less> |
279 | ||
280 | C<less> now does something useful (or at least it tries to). In fact, it | |
281 | has been turned into a lexical pragma. So, in your modules, you can now | |
282 | test whether your users have requested to use less CPU, or less memory, | |
283 | less magic, or maybe even less fat. See L<less> for more. (Joshua ben | |
284 | Jore) | |
285 | ||
3f10c77a RGS |
286 | =item C<Attribute::Handlers> |
287 | ||
288 | C<Attribute::Handlers> can now report the caller's file and line number. | |
289 | (David Feldman) | |
290 | ||
97f820fb RGS |
291 | =item C<B::Lint> |
292 | ||
293 | C<B::Lint> is now based on C<Module::Pluggable>, and so can be extended | |
294 | with plugins. (Joshua ben Jore) | |
295 | ||
296 | =item C<B> | |
297 | ||
298 | It's now possible to access the lexical pragma hints (C<%^H>) by using the | |
299 | method B::COP::hints_hash(). It returns a C<B::RHE> object, which in turn | |
300 | can be used to get a hash reference via the method B::RHE::HASH(). (Joshua | |
301 | ben Jore) | |
302 | ||
303 | =for p5p XXX document this in B.pm too | |
304 | ||
d5494b07 RGS |
305 | =back |
306 | ||
f6eae373 RGS |
307 | =head1 Utility Changes |
308 | ||
309 | =head1 Documentation | |
310 | ||
311 | =head1 Performance Enhancements | |
312 | ||
313 | =head1 Installation and Configuration Improvements | |
314 | ||
73966613 RGS |
315 | =head2 C++ compatibility |
316 | ||
317 | Efforts have been made to make perl and the core XS modules compilable | |
318 | with various C++ compilers (although the situation is not perfect with | |
319 | some of the compilers on some of the platforms tested.) | |
320 | ||
3f10c77a RGS |
321 | =head2 Static build on Win32 |
322 | ||
323 | It's now possible to build a C<perl-static.exe> that doesn't depend | |
324 | on C<perl59.dll> on Win32. See the Win32 makefiles for details. | |
e3c82801 | 325 | (Vadim Konovalov) |
3f10c77a | 326 | |
73966613 RGS |
327 | =head2 Ports |
328 | ||
329 | Perl has been reported to work on MidnightBSD. | |
330 | ||
f6eae373 RGS |
331 | =head1 Selected Bug Fixes |
332 | ||
49f595a6 RGS |
333 | PerlIO::scalar will now prevent writing to read-only scalars. Moreover, |
334 | seek() is now supported with PerlIO::scalar-based filehandles, the | |
97f820fb | 335 | underlying string being zero-filled as needed. (Rafael, Jarkko Hietaniemi) |
73966613 RGS |
336 | |
337 | study() never worked for UTF-8 strings, but could lead to false results. | |
338 | It's now a no-op on UTF-8 data. (Yves Orton) | |
339 | ||
49f595a6 RGS |
340 | The signals SIGILL, SIGBUS and SIGSEGV are now always delivered in an |
341 | "unsafe" manner (contrary to other signals, that are deferred until the | |
342 | perl interpreter reaches a reasonably stable state; see | |
97f820fb | 343 | L<perlipc/"Deferred Signals (Safe Signals)">). (Rafael) |
49f595a6 | 344 | |
5a093634 RGS |
345 | When a module or a file is loaded through an @INC-hook, and when this hook |
346 | has set a filename entry in %INC, __FILE__ is now set for this module | |
97f820fb RGS |
347 | accordingly to the contents of that %INC entry. (Rafael) |
348 | ||
349 | The C<-w> and C<-t> switches can now be used together without messing | |
350 | up what categories of warnings are activated or not. (Rafael) | |
5a093634 | 351 | |
f6eae373 RGS |
352 | =head1 New or Changed Diagnostics |
353 | ||
354 | =head1 Changed Internals | |
355 | ||
73966613 RGS |
356 | The anonymous hash and array constructors now take 1 op in the optree |
357 | instead of 3, now that pp_anonhash and pp_anonlist return a reference to | |
358 | an hash/array when the op is flagged with OPf_SPECIAL (Nicholas Clark). | |
359 | ||
97f820fb RGS |
360 | =for p5p XXX have we some docs on how to create regexp engine plugins, since that's now possible ? (perlreguts) |
361 | ||
362 | =for p5p XXX new BIND SV type, #29544, #29642 | |
363 | ||
f6eae373 RGS |
364 | =head1 Known Problems |
365 | ||
366 | =head2 Platform Specific Problems | |
367 | ||
368 | =head1 Reporting Bugs | |
369 | ||
370 | If you find what you think is a bug, you might check the articles | |
371 | recently posted to the comp.lang.perl.misc newsgroup and the perl | |
372 | bug database at http://rt.perl.org/rt3/ . There may also be | |
373 | information at http://www.perl.org/ , the Perl Home Page. | |
374 | ||
375 | If you believe you have an unreported bug, please run the B<perlbug> | |
376 | program included with your release. Be sure to trim your bug down | |
377 | to a tiny but sufficient test case. Your bug report, along with the | |
378 | output of C<perl -V>, will be sent off to perlbug@perl.org to be | |
379 | analysed by the Perl porting team. | |
380 | ||
381 | =head1 SEE ALSO | |
382 | ||
383 | The F<Changes> file for exhaustive details on what changed. | |
384 | ||
385 | The F<INSTALL> file for how to build Perl. | |
386 | ||
387 | The F<README> file for general stuff. | |
388 | ||
389 | The F<Artistic> and F<Copying> files for copyright information. | |
390 | ||
391 | =cut |