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1 =head1 NAME 2 3 perl595delta - 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 14 =head2 Tainting and printf 15 16 When perl is run under taint mode, C<printf()> and C<sprintf()> will now 17 reject any tainted format argument. (Rafael Garcia-Suarez) 18 19 =head2 undef and signal handlers 20 21 Undefining or deleting a signal handler via C<undef $SIG{FOO}> is now 22 equivalent to setting it to C<'DEFAULT'>. (Rafael) 23 24 =head2 strictures and array/hash dereferencing in defined() 25 26 C<defined @$foo> and C<defined %$bar> are now subject to C<strict 'refs'> 27 (that is, C<$foo> and C<$bar> shall be proper references there.) 28 (Nicholas Clark) 29 30 (However, C<defined(@foo)> and C<defined(%bar)> are discouraged constructs 31 anyway.) 32 33 =head2 C<(?p{})> has been removed 34 35 The regular expression construct C<(?p{})>, which was deprecated in perl 36 5.8, has been removed. Use C<(??{})> instead. (Rafael) 37 38 =head2 Pseudo-hashes have been removed 39 40 Support for pseudo-hashes has been removed from Perl 5.9. (The C<fields> 41 pragma remains here, but uses an alternate implementation.) 42 43 =head2 Removal of the bytecode compiler and of perlcc 44 45 C<perlcc>, the byteloader and the supporting modules (B::C, B::CC, 46 B::Bytecode, etc.) are no longer distributed with the perl sources. Those 47 experimental tools have never worked reliably, and, due to the lack of 48 volunteers to keep them in line with the perl interpreter developments, it 49 was decided to remove them instead of shipping a broken version of those. 50 The last version of those modules can be found with perl 5.9.4. 51 52 However the B compiler framework stays supported in the perl core, as with 53 the more useful modules it has permitted (among others, B::Deparse and 54 B::Concise). 55 56 =head2 Removal of the JPL 57 58 The JPL (Java-Perl Linguo) has been removed from the perl sources tarball. 59 60 =head2 Recursive inheritance detected earlier 61 62 Perl will now immediately throw an exception if you modify any package's 63 C<@ISA> in such a way that it would cause recursive inheritance. 64 65 Previously, the exception would not occur until Perl attempted to make 66 use of the recursive inheritance while resolving a method or doing a 67 C<$foo-E<gt>isa($bar)> lookup. 68 69 =head1 Core Enhancements 70 71 =head2 Regular expressions 72 73 =over 4 74 75 =item Recursive Patterns 76 77 It is now possible to write recursive patterns without using the C<(??{})> 78 construct. This new way is more efficient, and in many cases easier to 79 read. 80 81 Each capturing parenthesis can now be treated as an independent pattern 82 that can be entered by using the C<(?PARNO)> syntax (C<PARNO> standing for 83 "parenthesis number"). For example, the following pattern will match 84 nested balanced angle brackets: 85 86 / 87 ^ # start of line 88 ( # start capture buffer 1 89 < # match an opening angle bracket 90 (?: # match one of: 91 (?> # don't backtrack over the inside of this group 92 [^<>]+ # one or more non angle brackets 93 ) # end non backtracking group 94 | # ... or ... 95 (?1) # recurse to bracket 1 and try it again 96 )* # 0 or more times. 97 > # match a closing angle bracket 98 ) # end capture buffer one 99 $ # end of line 100 /x 101 102 Note, users experienced with PCRE will find that the Perl implementation 103 of this feature differs from the PCRE one in that it is possible to 104 backtrack into a recursed pattern, whereas in PCRE the recursion is 105 atomic or "possessive" in nature. (Yves Orton) 106 107 =item Named Capture Buffers 108 109 It is now possible to name capturing parenthesis in a pattern and refer to 110 the captured contents by name. The naming syntax is C<< (?<NAME>....) >>. 111 It's possible to backreference to a named buffer with the C<< \k<NAME> >> 112 syntax. In code, the new magical hashes C<%+> and C<%-> can be used to 113 access the contents of the capture buffers. 114 115 Thus, to replace all doubled chars, one could write 116 117 s/(?<letter>.)\k<letter>/$+{letter}/g 118 119 Only buffers with defined contents will be "visible" in the C<%+> hash, so 120 it's possible to do something like 121 122 foreach my $name (keys %+) { 123 print "content of buffer '$name' is $+{$name}\n"; 124 } 125 126 The C<%-> hash is a bit more complete, since it will contain array refs 127 holding values from all capture buffers similarly named, if there should 128 be many of them. 129 130 C<%+> and C<%-> are implemented as tied hashes through the new module 131 C<Tie::Hash::NamedCapture>. 132 133 Users exposed to the .NET regex engine will find that the perl 134 implementation differs in that the numerical ordering of the buffers 135 is sequential, and not "unnamed first, then named". Thus in the pattern 136 137 /(A)(?<B>B)(C)(?<D>D)/ 138 139 $1 will be 'A', $2 will be 'B', $3 will be 'C' and $4 will be 'D' and not 140 $1 is 'A', $2 is 'C' and $3 is 'B' and $4 is 'D' that a .NET programmer 141 would expect. This is considered a feature. :-) (Yves Orton) 142 143 =item Possessive Quantifiers 144 145 Perl now supports the "possessive quantifier" syntax of the "atomic match" 146 pattern. Basically a possessive quantifier matches as much as it can and never 147 gives any back. Thus it can be used to control backtracking. The syntax is 148 similar to non-greedy matching, except instead of using a '?' as the modifier 149 the '+' is used. Thus C<?+>, C<*+>, C<++>, C<{min,max}+> are now legal 150 quantifiers. (Yves Orton) 151 152 =item Backtracking control verbs 153 154 The regex engine now supports a number of special-purpose backtrack 155 control verbs: (*THEN), (*PRUNE), (*MARK), (*SKIP), (*COMMIT), (*FAIL) 156 and (*ACCEPT). See L<perlre> for their descriptions. (Yves Orton) 157 158 =item Relative backreferences 159 160 A new syntax C<\g{N}> or C<\gN> where "N" is a decimal integer allows a 161 safer form of back-reference notation as well as allowing relative 162 backreferences. This should make it easier to generate and embed patterns 163 that contain backreferences. See L<perlre/"Capture buffers">. (Yves Orton) 164 165 =item C<\K> escape 166 167 The functionality of Jeff Pinyan's module Regexp::Keep has been added to 168 the core. You can now use in regular expressions the special escape C<\K> 169 as a way to do something like floating length positive lookbehind. It is 170 also useful in substitutions like: 171 172 s/(foo)bar/$1/g 173 174 that can now be converted to 175 176 s/foo\Kbar//g 177 178 which is much more efficient. (Yves Orton) 179 180 =item Vertical and horizontal whitespace, and linebreak 181 182 Regular expressions now recognize the C<\v> and C<\h> escapes, that match 183 vertical and horizontal whitespace, respectively. C<\V> and C<\H> 184 logically match their complements. 185 186 C<\R> matches a generic linebreak, that is, vertical whitespace, plus 187 the multi-character sequence C<"\x0D\x0A">. 188 189 =back 190 191 =head2 The C<_> prototype 192 193 A new prototype character has been added. C<_> is equivalent to C<$> (it 194 denotes a scalar), but defaults to C<$_> if the corresponding argument 195 isn't supplied. Due to the optional nature of the argument, you can only 196 use it at the end of a prototype, or before a semicolon. 197 198 This has a small incompatible consequence: the prototype() function has 199 been adjusted to return C<_> for some built-ins in appropriate cases (for 200 example, C<prototype('CORE::rmdir')>). (Rafael) 201 202 =head2 UNITCHECK blocks 203 204 C<UNITCHECK>, a new special code block has been introduced, in addition to 205 C<BEGIN>, C<CHECK>, C<INIT> and C<END>. 206 207 C<CHECK> and C<INIT> blocks, while useful for some specialized purposes, 208 are always executed at the transition between the compilation and the 209 execution of the main program, and thus are useless whenever code is 210 loaded at runtime. On the other hand, C<UNITCHECK> blocks are executed 211 just after the unit which defined them has been compiled. See L<perlmod> 212 for more information. (Alex Gough) 213 214 =head2 readpipe() is now overridable 215 216 The built-in function readpipe() is now overridable. Overriding it permits 217 also to override its operator counterpart, C<qx//> (a.k.a. C<``>). 218 Moreover, it now defaults to C<$_> if no argument is provided. (Rafael) 219 220 =head2 default argument for readline() 221 222 readline() now defaults to C<*ARGV> if no argument is provided. (Rafael) 223 224 =head2 UCD 5.0.0 225 226 The copy of the Unicode Character Database included in Perl 5.9 has 227 been updated to version 5.0.0. 228 229 =head2 Smart match 230 231 The smart match operator (C<~~>) is now available by default (you don't 232 need to enable it with C<use feature> any longer). (Michael G Schwern) 233 234 =head2 Implicit loading of C<feature> 235 236 The C<feature> pragma is now implicitly loaded when you require a minimal 237 perl version (with the C<use VERSION> construct) greater than, or equal 238 to, 5.9.5. 239 240 =head1 Modules and Pragmas 241 242 =head2 New Pragma, C<mro> 243 244 A new pragma, C<mro> (for Method Resolution Order) has been added. It 245 permits to switch, on a per-class basis, the algorithm that perl uses to 246 find inherited methods in case of a multiple inheritance hierarchy. The 247 default MRO hasn't changed (DFS, for Depth First Search). Another MRO is 248 available: the C3 algorithm. See L<mro> for more information. 249 (Brandon Black) 250 251 Note that, due to changes in the implementation of class hierarchy search, 252 code that used to undef the C<*ISA> glob will most probably break. Anyway, 253 undef'ing C<*ISA> had the side-effect of removing the magic on the @ISA 254 array and should not have been done in the first place. 255 256 =head2 bignum, bigint, bigrat 257 258 The three numeric pragmas C<bignum>, C<bigint> and C<bigrat> are now 259 lexically scoped. (Tels) 260 261 =head2 Math::BigInt/Math::BigFloat 262 263 Many bugs have been fixed; noteworthy are comparisons with NaN, which 264 no longer warn about undef values. 265 266 The following things are new: 267 268 =over 4 269 270 =item config() 271 272 The config() method now also supports the calling-style 273 C<< config('lib') >> in addition to C<< config()->{'lib'} >>. 274 275 =item import() 276 277 Upon import, using C<< lib => 'Foo' >> now warns if the low-level library 278 cannot be found. To suppress the warning, you can use C<< try => 'Foo' >> 279 instead. To convert the warning into a die, use C<< only => 'Foo' >> 280 instead. 281 282 =item roundmode common 283 284 A rounding mode of C<common> is now supported. 285 286 =back 287 288 Also, support for the following methods has been added: 289 290 =over 4 291 292 =item bpi(), bcos(), bsin(), batan(), batan2() 293 294 =item bmuladd() 295 296 =item bexp(), bnok() 297 298 =item from_hex(), from_oct(), and from_bin() 299 300 =item as_oct() 301 302 =back 303 304 In addition, the default math-backend (Calc (Perl) and FastCalc (XS)) now 305 support storing numbers in parts with 9 digits instead of 7 on Perls with 306 either 64bit integer or long double support. This means math operations 307 scale better and are thus faster for really big numbers. 308 309 =head2 New Core Modules 310 311 =over 4 312 313 =item * 314 315 C<Locale::Maketext::Simple>, needed by CPANPLUS, is a simple wrapper around 316 C<Locale::Maketext::Lexicon>. Note that C<Locale::Maketext::Lexicon> isn't 317 included in the perl core; the behaviour of C<Locale::Maketext::Simple> 318 gracefully degrades when the later isn't present. 319 320 =item * 321 322 C<Params::Check> implements a generic input parsing/checking mechanism. It 323 is used by CPANPLUS. 324 325 =item * 326 327 C<Term::UI> simplifies the task to ask questions at a terminal prompt. 328 329 =item * 330 331 C<Object::Accessor> provides an interface to create per-object accessors. 332 333 =item * 334 335 C<Module::Pluggable> is a simple framework to create modules that accept 336 pluggable sub-modules. 337 338 =item * 339 340 C<Module::Load::Conditional> provides simple ways to query and possibly 341 load installed modules. 342 343 =item * 344 345 C<Time::Piece> provides an object oriented interface to time functions, 346 overriding the built-ins localtime() and gmtime(). 347 348 =item * 349 350 C<IPC::Cmd> helps to find and run external commands, possibly 351 interactively. 352 353 =item * 354 355 C<File::Fetch> provide a simple generic file fetching mechanism. 356 357 =item * 358 359 C<Log::Message> and C<Log::Message::Simple> are used by the log facility 360 of C<CPANPLUS>. 361 362 =item * 363 364 C<Archive::Extract> is a generic archive extraction mechanism 365 for F<.tar> (plain, gziped or bzipped) or F<.zip> files. 366 367 =item * 368 369 C<CPANPLUS> provides an API and a command-line tool to access the CPAN 370 mirrors. 371 372 =back 373 374 =head2 Module changes 375 376 =over 4 377 378 =item C<assertions> 379 380 The C<assertions> pragma, its submodules C<assertions::activate> and 381 C<assertions::compat> and the B<-A> command-line switch have been removed. 382 The interface was not judged mature enough for inclusion in a stable 383 release. 384 385 =item C<base> 386 387 The C<base> pragma now warns if a class tries to inherit from itself. 388 (Curtis "Ovid" Poe) 389 390 =item C<strict> and C<warnings> 391 392 C<strict> and C<warnings> will now complain loudly if they are loaded via 393 incorrect casing (as in C<use Strict;>). (Johan Vromans) 394 395 =item C<warnings> 396 397 The C<warnings> pragma doesn't load C<Carp> anymore. That means that code 398 that used C<Carp> routines without having loaded it at compile time might 399 need to be adjusted; typically, the following (faulty) code won't work 400 anymore, and will require parentheses to be added after the function name: 401 402 use warnings; 403 require Carp; 404 Carp::confess "argh"; 405 406 =item C<less> 407 408 C<less> now does something useful (or at least it tries to). In fact, it 409 has been turned into a lexical pragma. So, in your modules, you can now 410 test whether your users have requested to use less CPU, or less memory, 411 less magic, or maybe even less fat. See L<less> for more. (Joshua ben 412 Jore) 413 414 =item C<Attribute::Handlers> 415 416 C<Attribute::Handlers> can now report the caller's file and line number. 417 (David Feldman) 418 419 =item C<B::Lint> 420 421 C<B::Lint> is now based on C<Module::Pluggable>, and so can be extended 422 with plugins. (Joshua ben Jore) 423 424 =item C<B> 425 426 It's now possible to access the lexical pragma hints (C<%^H>) by using the 427 method B::COP::hints_hash(). It returns a C<B::RHE> object, which in turn 428 can be used to get a hash reference via the method B::RHE::HASH(). (Joshua 429 ben Jore) 430 431 =for p5p XXX document this in B.pm too 432 433 =item C<Thread> 434 435 As the old 5005thread threading model has been removed, in favor of the 436 ithreads scheme, the C<Thread> module is now a compatibility wrapper, to 437 be used in old code only. It has been removed from the default list of 438 dynamic extensions. 439 440 =back 441 442 =head1 Utility Changes 443 444 =head2 C<cpanp> 445 446 C<cpanp>, the CPANPLUS shell, has been added. (C<cpanp-run-perl>, an 447 helper for CPANPLUS operation, has been added too, but isn't intended for 448 direct use). 449 450 =head2 C<cpan2dist> 451 452 C<cpan2dist> is a new utility, that comes with CPANPLUS. It's a tool to 453 create distributions (or packages) from CPAN modules. 454 455 =head2 C<pod2html> 456 457 The output of C<pod2html> has been enhanced to be more customizable via 458 CSS. Some formatting problems were also corrected. (Jari Aalto) 459 460 =head1 Documentation 461 462 =head2 New manpage, perlunifaq 463 464 A new manual page, L<perlunifaq> (the Perl Unicode FAQ), has been added 465 (Juerd Waalboer). 466 467 =head1 Performance Enhancements 468 469 =head1 Installation and Configuration Improvements 470 471 =head2 C++ compatibility 472 473 Efforts have been made to make perl and the core XS modules compilable 474 with various C++ compilers (although the situation is not perfect with 475 some of the compilers on some of the platforms tested.) 476 477 =head2 Visual C++ 478 479 Perl now can be compiled with Microsoft Visual C++ 2005. 480 481 =head2 Static build on Win32 482 483 It's now possible to build a C<perl-static.exe> that doesn't depend 484 on C<perl59.dll> on Win32. See the Win32 makefiles for details. 485 (Vadim Konovalov) 486 487 =head2 win32 builds 488 489 All win32 builds (MS-Win, WinCE) have been merged and cleaned up. 490 491 =head2 C<d_pseudofork> and C<d_printf_format_null> 492 493 A new configuration variable, available as C<$Config{d_pseudofork}> in 494 the L<Config> module, has been added, to distinguish real fork() support 495 from fake pseudofork used on Windows platforms. 496 497 A new configuration variable, C<d_printf_format_null>, has been added, 498 to see if printf-like formats are allowed to be NULL. 499 500 =head2 Help 501 502 C<Configure -h> has been extended with the most used option. 503 504 Much less 'Whoa there' messages. 505 506 =head2 64bit systems 507 508 Better detection of 64bit(only) systems, and setting all the (library) 509 paths accordingly. 510 511 =head2 Ports 512 513 Perl has been reported to work on MidnightBSD. 514 515 Support for Cray XT4 Catamount/Qk has been added. 516 517 Vendor patches have been merged for RedHat and GenToo. 518 519 =head1 Selected Bug Fixes 520 521 PerlIO::scalar will now prevent writing to read-only scalars. Moreover, 522 seek() is now supported with PerlIO::scalar-based filehandles, the 523 underlying string being zero-filled as needed. (Rafael, Jarkko Hietaniemi) 524 525 study() never worked for UTF-8 strings, but could lead to false results. 526 It's now a no-op on UTF-8 data. (Yves Orton) 527 528 The signals SIGILL, SIGBUS and SIGSEGV are now always delivered in an 529 "unsafe" manner (contrary to other signals, that are deferred until the 530 perl interpreter reaches a reasonably stable state; see 531 L<perlipc/"Deferred Signals (Safe Signals)">). (Rafael) 532 533 When a module or a file is loaded through an @INC-hook, and when this hook 534 has set a filename entry in %INC, __FILE__ is now set for this module 535 accordingly to the contents of that %INC entry. (Rafael) 536 537 The C<-w> and C<-t> switches can now be used together without messing 538 up what categories of warnings are activated or not. (Rafael) 539 540 Duping a filehandle which has the C<:utf8> PerlIO layer set will now 541 properly carry that layer on the duped filehandle. (Rafael) 542 543 Localizing an hash element whose key was given as a variable didn't work 544 correctly if the variable was changed while the local() was in effect (as 545 in C<local $h{$x}; ++$x>). (Bo Lindbergh) 546 547 =head1 New or Changed Diagnostics 548 549 =head2 Deprecations 550 551 Two deprecation warnings have been added: (Rafael) 552 553 Opening dirhandle %s also as a file 554 Opening filehandle %s also as a directory 555 556 =head1 Changed Internals 557 558 The anonymous hash and array constructors now take 1 op in the optree 559 instead of 3, now that pp_anonhash and pp_anonlist return a reference to 560 an hash/array when the op is flagged with OPf_SPECIAL (Nicholas Clark). 561 562 =for p5p XXX have we some docs on how to create regexp engine plugins, since that's now possible ? (perlreguts) 563 564 =for p5p XXX new BIND SV type, #29544, #29642 565 566 =head1 Known Problems 567 568 =head2 Platform Specific Problems 569 570 =head1 Reporting Bugs 571 572 If you find what you think is a bug, you might check the articles 573 recently posted to the comp.lang.perl.misc newsgroup and the perl 574 bug database at http://rt.perl.org/rt3/ . There may also be 575 information at http://www.perl.org/ , the Perl Home Page. 576 577 If you believe you have an unreported bug, please run the B<perlbug> 578 program included with your release. Be sure to trim your bug down 579 to a tiny but sufficient test case. Your bug report, along with the 580 output of C<perl -V>, will be sent off to perlbug@perl.org to be 581 analysed by the Perl porting team. 582 583 =head1 SEE ALSO 584 585 The F<Changes> file for exhaustive details on what changed. 586 587 The F<INSTALL> file for how to build Perl. 588 589 The F<README> file for general stuff. 590 591 The F<Artistic> and F<Copying> files for copyright information. 592 593 =cut
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