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1 =head1 NAME 2 3 perl581delta - what is new for perl v5.8.1 4 5 =head1 DESCRIPTION 6 7 This document describes differences between the 5.8.0 release and 8 the 5.8.1 release. 9 10 If you are upgrading from an earlier release such as 5.6.1, first read 11 the L<perl58delta>, which describes differences between 5.6.0 and 12 5.8.0. 13 14 In case you are wondering about 5.6.1, it was bug-fix-wise rather 15 identical to the development release 5.7.1. Confused? This timeline 16 hopefully helps a bit: it lists the new major releases, their maintenance 17 releases, and the development releases. 18 19 New Maintenance Development 20 21 5.6.0 2000-Mar-22 22 5.7.0 2000-Sep-02 23 5.6.1 2001-Apr-08 24 5.7.1 2001-Apr-09 25 5.7.2 2001-Jul-13 26 5.7.3 2002-Mar-05 27 5.8.0 2002-Jul-18 28 5.8.1 2003-Sep-25 29 30 =head1 Incompatible Changes 31 32 =head2 Hash Randomisation 33 34 Mainly due to security reasons, the "random ordering" of hashes 35 has been made even more random. Previously while the order of hash 36 elements from keys(), values(), and each() was essentially random, 37 it was still repeatable. Now, however, the order varies between 38 different runs of Perl. 39 40 B<Perl has never guaranteed any ordering of the hash keys>, and the 41 ordering has already changed several times during the lifetime of 42 Perl 5. Also, the ordering of hash keys has always been, and 43 continues to be, affected by the insertion order. 44 45 The added randomness may affect applications. 46 47 One possible scenario is when output of an application has included 48 hash data. For example, if you have used the Data::Dumper module to 49 dump data into different files, and then compared the files to see 50 whether the data has changed, now you will have false positives since 51 the order in which hashes are dumped will vary. In general the cure 52 is to sort the keys (or the values); in particular for Data::Dumper to 53 use the C<Sortkeys> option. If some particular order is really 54 important, use tied hashes: for example the Tie::IxHash module 55 which by default preserves the order in which the hash elements 56 were added. 57 58 More subtle problem is reliance on the order of "global destruction". 59 That is what happens at the end of execution: Perl destroys all data 60 structures, including user data. If your destructors (the DESTROY 61 subroutines) have assumed any particular ordering to the global 62 destruction, there might be problems ahead. For example, in a 63 destructor of one object you cannot assume that objects of any other 64 class are still available, unless you hold a reference to them. 65 If the environment variable PERL_DESTRUCT_LEVEL is set to a non-zero 66 value, or if Perl is exiting a spawned thread, it will also destruct 67 the ordinary references and the symbol tables that are no longer in use. 68 You can't call a class method or an ordinary function on a class that 69 has been collected that way. 70 71 The hash randomisation is certain to reveal hidden assumptions about 72 some particular ordering of hash elements, and outright bugs: it 73 revealed a few bugs in the Perl core and core modules. 74 75 To disable the hash randomisation in runtime, set the environment 76 variable PERL_HASH_SEED to 0 (zero) before running Perl (for more 77 information see L<perlrun/PERL_HASH_SEED>), or to disable the feature 78 completely in compile time, compile with C<-DNO_HASH_SEED> (see F<INSTALL>). 79 80 See L<perlsec/"Algorithmic Complexity Attacks"> for the original 81 rationale behind this change. 82 83 =head2 UTF-8 On Filehandles No Longer Activated By Locale 84 85 In Perl 5.8.0 all filehandles, including the standard filehandles, 86 were implicitly set to be in Unicode UTF-8 if the locale settings 87 indicated the use of UTF-8. This feature caused too many problems, 88 so the feature was turned off and redesigned: see L</"Core Enhancements">. 89 90 =head2 Single-number v-strings are no longer v-strings before "=>" 91 92 The version strings or v-strings (see L<perldata/"Version Strings">) 93 feature introduced in Perl 5.6.0 has been a source of some confusion-- 94 especially when the user did not want to use it, but Perl thought it 95 knew better. Especially troublesome has been the feature that before 96 a "=>" a version string (a "v" followed by digits) has been interpreted 97 as a v-string instead of a string literal. In other words: 98 99 %h = ( v65 => 42 ); 100 101 has meant since Perl 5.6.0 102 103 %h = ( 'A' => 42 ); 104 105 (at least in platforms of ASCII progeny) Perl 5.8.1 restores the 106 more natural interpretation 107 108 %h = ( 'v65' => 42 ); 109 110 The multi-number v-strings like v65.66 and 65.66.67 still continue to 111 be v-strings in Perl 5.8. 112 113 =head2 (Win32) The -C Switch Has Been Repurposed 114 115 The -C switch has changed in an incompatible way. The old semantics 116 of this switch only made sense in Win32 and only in the "use utf8" 117 universe in 5.6.x releases, and do not make sense for the Unicode 118 implementation in 5.8.0. Since this switch could not have been used 119 by anyone, it has been repurposed. The behavior that this switch 120 enabled in 5.6.x releases may be supported in a transparent, 121 data-dependent fashion in a future release. 122 123 For the new life of this switch, see L<"UTF-8 no longer default under 124 UTF-8 locales">, and L<perlrun/-C>. 125 126 =head2 (Win32) The /d Switch Of cmd.exe 127 128 Perl 5.8.1 uses the /d switch when running the cmd.exe shell 129 internally for system(), backticks, and when opening pipes to external 130 programs. The extra switch disables the execution of AutoRun commands 131 from the registry, which is generally considered undesirable when 132 running external programs. If you wish to retain compatibility with 133 the older behavior, set PERL5SHELL in your environment to C<cmd /x/c>. 134 135 =head1 Core Enhancements 136 137 =head2 UTF-8 no longer default under UTF-8 locales 138 139 In Perl 5.8.0 many Unicode features were introduced. One of them 140 was found to be of more nuisance than benefit: the automagic 141 (and silent) "UTF-8-ification" of filehandles, including the 142 standard filehandles, if the user's locale settings indicated 143 use of UTF-8. 144 145 For example, if you had C<en_US.UTF-8> as your locale, your STDIN and 146 STDOUT were automatically "UTF-8", in other words an implicit 147 binmode(..., ":utf8") was made. This meant that trying to print, say, 148 chr(0xff), ended up printing the bytes 0xc3 0xbf. Hardly what 149 you had in mind unless you were aware of this feature of Perl 5.8.0. 150 The problem is that the vast majority of people weren't: for example 151 in RedHat releases 8 and 9 the B<default> locale setting is UTF-8, so 152 all RedHat users got UTF-8 filehandles, whether they wanted it or not. 153 The pain was intensified by the Unicode implementation of Perl 5.8.0 154 (still) having nasty bugs, especially related to the use of s/// and 155 tr///. (Bugs that have been fixed in 5.8.1) 156 157 Therefore a decision was made to backtrack the feature and change it 158 from implicit silent default to explicit conscious option. The new 159 Perl command line option C<-C> and its counterpart environment 160 variable PERL_UNICODE can now be used to control how Perl and Unicode 161 interact at interfaces like I/O and for example the command line 162 arguments. See L<perlrun/-C> and L<perlrun/PERL_UNICODE> for more 163 information. 164 165 =head2 Unsafe signals again available 166 167 In Perl 5.8.0 the so-called "safe signals" were introduced. This 168 means that Perl no longer handles signals immediately but instead 169 "between opcodes", when it is safe to do so. The earlier immediate 170 handling easily could corrupt the internal state of Perl, resulting 171 in mysterious crashes. 172 173 However, the new safer model has its problems too. Because now an 174 opcode, a basic unit of Perl execution, is never interrupted but 175 instead let to run to completion, certain operations that can take a 176 long time now really do take a long time. For example, certain 177 network operations have their own blocking and timeout mechanisms, and 178 being able to interrupt them immediately would be nice. 179 180 Therefore perl 5.8.1 introduces a "backdoor" to restore the pre-5.8.0 181 (pre-5.7.3, really) signal behaviour. Just set the environment variable 182 PERL_SIGNALS to C<unsafe>, and the old immediate (and unsafe) 183 signal handling behaviour returns. See L<perlrun/PERL_SIGNALS> 184 and L<perlipc/"Deferred Signals (Safe Signals)">. 185 186 In completely unrelated news, you can now use safe signals with 187 POSIX::SigAction. See L<POSIX/POSIX::SigAction>. 188 189 =head2 Tied Arrays with Negative Array Indices 190 191 Formerly, the indices passed to C<FETCH>, C<STORE>, C<EXISTS>, and 192 C<DELETE> methods in tied array class were always non-negative. If 193 the actual argument was negative, Perl would call FETCHSIZE implicitly 194 and add the result to the index before passing the result to the tied 195 array method. This behaviour is now optional. If the tied array class 196 contains a package variable named C<$NEGATIVE_INDICES> which is set to 197 a true value, negative values will be passed to C<FETCH>, C<STORE>, 198 C<EXISTS>, and C<DELETE> unchanged. 199 200 =head2 local ${$x} 201 202 The syntaxes 203 204 local ${$x} 205 local @{$x} 206 local %{$x} 207 208 now do localise variables, given that the $x is a valid variable name. 209 210 =head2 Unicode Character Database 4.0.0 211 212 The copy of the Unicode Character Database included in Perl 5.8 has 213 been updated to 4.0.0 from 3.2.0. This means for example that the 214 Unicode character properties are as in Unicode 4.0.0. 215 216 =head2 Deprecation Warnings 217 218 There is one new feature deprecation. Perl 5.8.0 forgot to add 219 some deprecation warnings, these warnings have now been added. 220 Finally, a reminder of an impending feature removal. 221 222 =head3 (Reminder) Pseudo-hashes are deprecated (really) 223 224 Pseudo-hashes were deprecated in Perl 5.8.0 and will be removed in 225 Perl 5.10.0, see L<perl58delta> for details. Each attempt to access 226 pseudo-hashes will trigger the warning C<Pseudo-hashes are deprecated>. 227 If you really want to continue using pseudo-hashes but not to see the 228 deprecation warnings, use: 229 230 no warnings 'deprecated'; 231 232 Or you can continue to use the L<fields> pragma, but please don't 233 expect the data structures to be pseudohashes any more. 234 235 =head3 (Reminder) 5.005-style threads are deprecated (really) 236 237 5.005-style threads (activated by C<use Thread;>) were deprecated in 238 Perl 5.8.0 and will be removed after Perl 5.8, see L<perl58delta> for 239 details. Each 5.005-style thread creation will trigger the warning 240 C<5.005 threads are deprecated>. If you really want to continue 241 using the 5.005 threads but not to see the deprecation warnings, use: 242 243 no warnings 'deprecated'; 244 245 =head3 (Reminder) The $* variable is deprecated (really) 246 247 The C<$*> variable controlling multi-line matching has been deprecated 248 and will be removed after 5.8. The variable has been deprecated for a 249 long time, and a deprecation warning C<Use of $* is deprecated> is given, 250 now the variable will just finally be removed. The functionality has 251 been supplanted by the C</s> and C</m> modifiers on pattern matching. 252 If you really want to continue using the C<$*>-variable but not to see 253 the deprecation warnings, use: 254 255 no warnings 'deprecated'; 256 257 =head2 Miscellaneous Enhancements 258 259 C<map> in void context is no longer expensive. C<map> is now context 260 aware, and will not construct a list if called in void context. 261 262 If a socket gets closed by the server while printing to it, the client 263 now gets a SIGPIPE. While this new feature was not planned, it fell 264 naturally out of PerlIO changes, and is to be considered an accidental 265 feature. 266 267 PerlIO::get_layers(FH) returns the names of the PerlIO layers 268 active on a filehandle. 269 270 PerlIO::via layers can now have an optional UTF8 method to 271 indicate whether the layer wants to "auto-:utf8" the stream. 272 273 utf8::is_utf8() has been added as a quick way to test whether 274 a scalar is encoded internally in UTF-8 (Unicode). 275 276 =head1 Modules and Pragmata 277 278 =head2 Updated Modules And Pragmata 279 280 The following modules and pragmata have been updated since Perl 5.8.0: 281 282 =over 4 283 284 =item base 285 286 =item B::Bytecode 287 288 In much better shape than it used to be. Still far from perfect, but 289 maybe worth a try. 290 291 =item B::Concise 292 293 =item B::Deparse 294 295 =item Benchmark 296 297 An optional feature, C<:hireswallclock>, now allows for high 298 resolution wall clock times (uses Time::HiRes). 299 300 =item ByteLoader 301 302 See B::Bytecode. 303 304 =item bytes 305 306 Now has bytes::substr. 307 308 =item CGI 309 310 =item charnames 311 312 One can now have custom character name aliases. 313 314 =item CPAN 315 316 There is now a simple command line frontend to the CPAN.pm 317 module called F<cpan>. 318 319 =item Data::Dumper 320 321 A new option, Pair, allows choosing the separator between hash keys 322 and values. 323 324 =item DB_File 325 326 =item Devel::PPPort 327 328 =item Digest::MD5 329 330 =item Encode 331 332 Significant updates on the encoding pragma functionality 333 (tr/// and the DATA filehandle, formats). 334 335 If a filehandle has been marked as to have an encoding, unmappable 336 characters are detected already during input, not later (when the 337 corrupted data is being used). 338 339 The ISO 8859-6 conversion table has been corrected (the 0x30..0x39 340 erroneously mapped to U+0660..U+0669, instead of U+0030..U+0039). The 341 GSM 03.38 conversion did not handle escape sequences correctly. The 342 UTF-7 encoding has been added (making Encode feature-complete with 343 Unicode::String). 344 345 =item fields 346 347 =item libnet 348 349 =item Math::BigInt 350 351 A lot of bugs have been fixed since v1.60, the version included in Perl 352 v5.8.0. Especially noteworthy are the bug in Calc that caused div and mod to 353 fail for some large values, and the fixes to the handling of bad inputs. 354 355 Some new features were added, e.g. the broot() method, you can now pass 356 parameters to config() to change some settings at runtime, and it is now 357 possible to trap the creation of NaN and infinity. 358 359 As usual, some optimizations took place and made the math overall a tad 360 faster. In some cases, quite a lot faster, actually. Especially alternative 361 libraries like Math::BigInt::GMP benefit from this. In addition, a lot of the 362 quite clunky routines like fsqrt() and flog() are now much much faster. 363 364 =item MIME::Base64 365 366 =item NEXT 367 368 Diamond inheritance now works. 369 370 =item Net::Ping 371 372 =item PerlIO::scalar 373 374 Reading from non-string scalars (like the special variables, see 375 L<perlvar>) now works. 376 377 =item podlators 378 379 =item Pod::LaTeX 380 381 =item PodParsers 382 383 =item Pod::Perldoc 384 385 Complete rewrite. As a side-effect, no longer refuses to startup when 386 run by root. 387 388 =item Scalar::Util 389 390 New utilities: refaddr, isvstring, looks_like_number, set_prototype. 391 392 =item Storable 393 394 Can now store code references (via B::Deparse, so not foolproof). 395 396 =item strict 397 398 Earlier versions of the strict pragma did not check the parameters 399 implicitly passed to its "import" (use) and "unimport" (no) routine. 400 This caused the false idiom such as: 401 402 use strict qw(@ISA); 403 @ISA = qw(Foo); 404 405 This however (probably) raised the false expectation that the strict 406 refs, vars and subs were being enforced (and that @ISA was somehow 407 "declared"). But the strict refs, vars, and subs are B<not> enforced 408 when using this false idiom. 409 410 Starting from Perl 5.8.1, the above B<will> cause an error to be 411 raised. This may cause programs which used to execute seemingly 412 correctly without warnings and errors to fail when run under 5.8.1. 413 This happens because 414 415 use strict qw(@ISA); 416 417 will now fail with the error: 418 419 Unknown 'strict' tag(s) '@ISA' 420 421 The remedy to this problem is to replace this code with the correct idiom: 422 423 use strict; 424 use vars qw(@ISA); 425 @ISA = qw(Foo); 426 427 =item Term::ANSIcolor 428 429 =item Test::Harness 430 431 Now much more picky about extra or missing output from test scripts. 432 433 =item Test::More 434 435 =item Test::Simple 436 437 =item Text::Balanced 438 439 =item Time::HiRes 440 441 Use of nanosleep(), if available, allows mixing subsecond sleeps with 442 alarms. 443 444 =item threads 445 446 Several fixes, for example for join() problems and memory 447 leaks. In some platforms (like Linux) that use glibc the minimum memory 448 footprint of one ithread has been reduced by several hundred kilobytes. 449 450 =item threads::shared 451 452 Many memory leaks have been fixed. 453 454 =item Unicode::Collate 455 456 =item Unicode::Normalize 457 458 =item Win32::GetFolderPath 459 460 =item Win32::GetOSVersion 461 462 Now returns extra information. 463 464 =back 465 466 =head1 Utility Changes 467 468 The C<h2xs> utility now produces a more modern layout: 469 F<Foo-Bar/lib/Foo/Bar.pm> instead of F<Foo/Bar/Bar.pm>. 470 Also, the boilerplate test is now called F<t/Foo-Bar.t> 471 instead of F<t/1.t>. 472 473 The Perl debugger (F<lib/perl5db.pl>) has now been extensively 474 documented and bugs found while documenting have been fixed. 475 476 C<perldoc> has been rewritten from scratch to be more robust and 477 feature rich. 478 479 C<perlcc -B> works now at least somewhat better, while C<perlcc -c> 480 is rather more broken. (The Perl compiler suite as a whole continues 481 to be experimental.) 482 483 =head1 New Documentation 484 485 perl573delta has been added to list the differences between the 486 (now quite obsolete) development releases 5.7.2 and 5.7.3. 487 488 perl58delta has been added: it is the perldelta of 5.8.0, detailing 489 the differences between 5.6.0 and 5.8.0. 490 491 perlartistic has been added: it is the Artistic License in pod format, 492 making it easier for modules to refer to it. 493 494 perlcheat has been added: it is a Perl cheat sheet. 495 496 perlgpl has been added: it is the GNU General Public License in pod 497 format, making it easier for modules to refer to it. 498 499 perlmacosx has been added to tell about the installation and use 500 of Perl in Mac OS X. 501 502 perlos400 has been added to tell about the installation and use 503 of Perl in OS/400 PASE. 504 505 perlreref has been added: it is a regular expressions quick reference. 506 507 =head1 Installation and Configuration Improvements 508 509 The UNIX standard Perl location, F</usr/bin/perl>, is no longer 510 overwritten by default if it exists. This change was very prudent 511 because so many UNIX vendors already provide a F</usr/bin/perl>, 512 but simultaneously many system utilities may depend on that 513 exact version of Perl, so better not to overwrite it. 514 515 One can now specify installation directories for site and vendor man 516 and HTML pages, and site and vendor scripts. See F<INSTALL>. 517 518 One can now specify a destination directory for Perl installation 519 by specifying the DESTDIR variable for C<make install>. (This feature 520 is slightly different from the previous C<Configure -Dinstallprefix=...>.) 521 See F<INSTALL>. 522 523 gcc versions 3.x introduced a new warning that caused a lot of noise 524 during Perl compilation: C<gcc -Ialreadyknowndirectory (warning: 525 changing search order)>. This warning has now been avoided by 526 Configure weeding out such directories before the compilation. 527 528 One can now build subsets of Perl core modules by using the 529 Configure flags C<-Dnoextensions=...> and C<-Donlyextensions=...>, 530 see F<INSTALL>. 531 532 =head2 Platform-specific enhancements 533 534 In Cygwin Perl can now be built with threads (C<Configure -Duseithreads>). 535 This works with both Cygwin 1.3.22 and Cygwin 1.5.3. 536 537 In newer FreeBSD releases Perl 5.8.0 compilation failed because of 538 trying to use F<malloc.h>, which in FreeBSD is just a dummy file, and 539 a fatal error to even try to use. Now F<malloc.h> is not used. 540 541 Perl is now known to build also in Hitachi HI-UXMPP. 542 543 Perl is now known to build again in LynxOS. 544 545 Mac OS X now installs with Perl version number embedded in 546 installation directory names for easier upgrading of user-compiled 547 Perl, and the installation directories in general are more standard. 548 In other words, the default installation no longer breaks the 549 Apple-provided Perl. On the other hand, with C<Configure -Dprefix=/usr> 550 you can now really replace the Apple-supplied Perl (B<please be careful>). 551 552 Mac OS X now builds Perl statically by default. This change was done 553 mainly for faster startup times. The Apple-provided Perl is still 554 dynamically linked and shared, and you can enable the sharedness for 555 your own Perl builds by C<Configure -Duseshrplib>. 556 557 Perl has been ported to IBM's OS/400 PASE environment. The best way 558 to build a Perl for PASE is to use an AIX host as a cross-compilation 559 environment. See README.os400. 560 561 Yet another cross-compilation option has been added: now Perl builds 562 on OpenZaurus, an Linux distribution based on Mandrake + Embedix for 563 the Sharp Zaurus PDA. See the Cross/README file. 564 565 Tru64 when using gcc 3 drops the optimisation for F<toke.c> to C<-O2> 566 because of gigantic memory use with the default C<-O3>. 567 568 Tru64 can now build Perl with the newer Berkeley DBs. 569 570 Building Perl on WinCE has been much enhanced, see F<README.ce> 571 and F<README.perlce>. 572 573 =head1 Selected Bug Fixes 574 575 =head2 Closures, eval and lexicals 576 577 There have been many fixes in the area of anonymous subs, lexicals and 578 closures. Although this means that Perl is now more "correct", it is 579 possible that some existing code will break that happens to rely on 580 the faulty behaviour. In practice this is unlikely unless your code 581 contains a very complex nesting of anonymous subs, evals and lexicals. 582 583 =head2 Generic fixes 584 585 If an input filehandle is marked C<:utf8> and Perl sees illegal UTF-8 586 coming in when doing C<< <FH> >>, if warnings are enabled a warning is 587 immediately given - instead of being silent about it and Perl being 588 unhappy about the broken data later. (The C<:encoding(utf8)> layer 589 also works the same way.) 590 591 binmode(SOCKET, ":utf8") only worked on the input side, not on the 592 output side of the socket. Now it works both ways. 593 594 For threaded Perls certain system database functions like getpwent() 595 and getgrent() now grow their result buffer dynamically, instead of 596 failing. This means that at sites with lots of users and groups the 597 functions no longer fail by returning only partial results. 598 599 Perl 5.8.0 had accidentally broken the capability for users 600 to define their own uppercase<->lowercase Unicode mappings 601 (as advertised by the Camel). This feature has been fixed and 602 is also documented better. 603 604 In 5.8.0 this 605 606 $some_unicode .= <FH>; 607 608 didn't work correctly but instead corrupted the data. This has now 609 been fixed. 610 611 Tied methods like FETCH etc. may now safely access tied values, i.e. 612 resulting in a recursive call to FETCH etc. Remember to break the 613 recursion, though. 614 615 At startup Perl blocks the SIGFPE signal away since there isn't much 616 Perl can do about it. Previously this blocking was in effect also for 617 programs executed from within Perl. Now Perl restores the original 618 SIGFPE handling routine, whatever it was, before running external 619 programs. 620 621 Linenumbers in Perl scripts may now be greater than 65536, or 2**16. 622 (Perl scripts have always been able to be larger than that, it's just 623 that the linenumber for reported errors and warnings have "wrapped 624 around".) While scripts that large usually indicate a need to rethink 625 your code a bit, such Perl scripts do exist, for example as results 626 from generated code. Now linenumbers can go all the way to 627 4294967296, or 2**32. 628 629 =head2 Platform-specific fixes 630 631 Linux 632 633 =over 4 634 635 =item * 636 637 Setting $0 works again (with certain limitations that 638 Perl cannot do much about: see L<perlvar/$0>) 639 640 =back 641 642 HP-UX 643 644 =over 4 645 646 =item * 647 648 Setting $0 now works. 649 650 =back 651 652 VMS 653 654 =over 4 655 656 =item * 657 658 Configuration now tests for the presence of C<poll()>, and IO::Poll 659 now uses the vendor-supplied function if detected. 660 661 =item * 662 663 A rare access violation at Perl start-up could occur if the Perl image was 664 installed with privileges or if there was an identifier with the 665 subsystem attribute set in the process's rightslist. Either of these 666 circumstances triggered tainting code that contained a pointer bug. 667 The faulty pointer arithmetic has been fixed. 668 669 =item * 670 671 The length limit on values (not keys) in the %ENV hash has been raised 672 from 255 bytes to 32640 bytes (except when the PERL_ENV_TABLES setting 673 overrides the default use of logical names for %ENV). If it is 674 necessary to access these long values from outside Perl, be aware that 675 they are implemented using search list logical names that store the 676 value in pieces, each 255-byte piece (up to 128 of them) being an 677 element in the search list. When doing a lookup in %ENV from within 678 Perl, the elements are combined into a single value. The existing 679 VMS-specific ability to access individual elements of a search list 680 logical name via the $ENV{'foo;N'} syntax (where N is the search list 681 index) is unimpaired. 682 683 =item * 684 685 The piping implementation now uses local rather than global DCL 686 symbols for inter-process communication. 687 688 =item * 689 690 File::Find could become confused when navigating to a relative 691 directory whose name collided with a logical name. This problem has 692 been corrected by adding directory syntax to relative path names, thus 693 preventing logical name translation. 694 695 =back 696 697 Win32 698 699 =over 4 700 701 =item * 702 703 A memory leak in the fork() emulation has been fixed. 704 705 =item * 706 707 The return value of the ioctl() built-in function was accidentally 708 broken in 5.8.0. This has been corrected. 709 710 =item * 711 712 The internal message loop executed by perl during blocking operations 713 sometimes interfered with messages that were external to Perl. 714 This often resulted in blocking operations terminating prematurely or 715 returning incorrect results, when Perl was executing under environments 716 that could generate Windows messages. This has been corrected. 717 718 =item * 719 720 Pipes and sockets are now automatically in binary mode. 721 722 =item * 723 724 The four-argument form of select() did not preserve $! (errno) properly 725 when there were errors in the underlying call. This is now fixed. 726 727 =item * 728 729 The "CR CR LF" problem of has been fixed, binmode(FH, ":crlf") 730 is now effectively a no-op. 731 732 =back 733 734 =head1 New or Changed Diagnostics 735 736 All the warnings related to pack() and unpack() were made more 737 informative and consistent. 738 739 =head2 Changed "A thread exited while %d threads were running" 740 741 The old version 742 743 A thread exited while %d other threads were still running 744 745 was misleading because the "other" included also the thread giving 746 the warning. 747 748 =head2 Removed "Attempt to clear a restricted hash" 749 750 It is not illegal to clear a restricted hash, so the warning 751 was removed. 752 753 =head2 New "Illegal declaration of anonymous subroutine" 754 755 You must specify the block of code for C<sub>. 756 757 =head2 Changed "Invalid range "%s" in transliteration operator" 758 759 The old version 760 761 Invalid [] range "%s" in transliteration operator 762 763 was simply wrong because there are no "[] ranges" in tr///. 764 765 =head2 New "Missing control char name in \c" 766 767 Self-explanatory. 768 769 =head2 New "Newline in left-justified string for %s" 770 771 The padding spaces would appear after the newline, which is 772 probably not what you had in mind. 773 774 =head2 New "Possible precedence problem on bitwise %c operator" 775 776 If you think this 777 778 $x & $y == 0 779 780 tests whether the bitwise AND of $x and $y is zero, 781 you will like this warning. 782 783 =head2 New "Pseudo-hashes are deprecated" 784 785 This warning should have been already in 5.8.0, since they are. 786 787 =head2 New "read() on %s filehandle %s" 788 789 You cannot read() (or sysread()) from a closed or unopened filehandle. 790 791 =head2 New "5.005 threads are deprecated" 792 793 This warning should have been already in 5.8.0, since they are. 794 795 =head2 New "Tied variable freed while still in use" 796 797 Something pulled the plug on a live tied variable, Perl plays 798 safe by bailing out. 799 800 =head2 New "To%s: illegal mapping '%s'" 801 802 An illegal user-defined Unicode casemapping was specified. 803 804 =head2 New "Use of freed value in iteration" 805 806 Something modified the values being iterated over. This is not good. 807 808 =head1 Changed Internals 809 810 These news matter to you only if you either write XS code or like to 811 know about or hack Perl internals (using Devel::Peek or any of the 812 C<B::> modules counts), or like to run Perl with the C<-D> option. 813 814 The embedding examples of L<perlembed> have been reviewed to be 815 up to date and consistent: for example, the correct use of 816 PERL_SYS_INIT3() and PERL_SYS_TERM(). 817 818 Extensive reworking of the pad code (the code responsible 819 for lexical variables) has been conducted by Dave Mitchell. 820 821 Extensive work on the v-strings by John Peacock. 822 823 UTF-8 length and position cache: to speed up the handling of Unicode 824 (UTF-8) scalars, a cache was introduced. Potential problems exist if 825 an extension bypasses the official APIs and directly modifies the PV 826 of an SV: the UTF-8 cache does not get cleared as it should. 827 828 APIs obsoleted in Perl 5.8.0, like sv_2pv, sv_catpvn, sv_catsv, 829 sv_setsv, are again available. 830 831 Certain Perl core C APIs like cxinc and regatom are no longer 832 available at all to code outside the Perl core of the Perl core 833 extensions. This is intentional. They never should have been 834 available with the shorter names, and if you application depends on 835 them, you should (be ashamed and) contact perl5-porters to discuss 836 what are the proper APIs. 837 838 Certain Perl core C APIs like C<Perl_list> are no longer available 839 without their C<Perl_> prefix. If your XS module stops working 840 because some functions cannot be found, in many cases a simple fix is 841 to add the C<Perl_> prefix to the function and the thread context 842 C<aTHX_> as the first argument of the function call. This is also how 843 it should always have been done: letting the Perl_-less forms to leak 844 from the core was an accident. For cleaner embedding you can also 845 force this for all APIs by defining at compile time the cpp define 846 PERL_NO_SHORT_NAMES. 847 848 Perl_save_bool() has been added. 849 850 Regexp objects (those created with C<qr>) now have S-magic rather than 851 R-magic. This fixed regexps of the form /...(??{...;$x})/ to no 852 longer ignore changes made to $x. The S-magic avoids dropping 853 the caching optimization and making (??{...}) constructs obscenely 854 slow (and consequently useless). See also L<perlguts/"Magic Variables">. 855 Regexp::Copy was affected by this change. 856 857 The Perl internal debugging macros DEBUG() and DEB() have been renamed 858 to PERL_DEBUG() and PERL_DEB() to avoid namespace conflicts. 859 860 C<-DL> removed (the leaktest had been broken and unsupported for years, 861 use alternative debugging mallocs or tools like valgrind and Purify). 862 863 Verbose modifier C<v> added for C<-DXv> and C<-Dsv>, see L<perlrun>. 864 865 =head1 New Tests 866 867 In Perl 5.8.0 there were about 69000 separate tests in about 700 test files, 868 in Perl 5.8.1 there are about 77000 separate tests in about 780 test files. 869 The exact numbers depend on the Perl configuration and on the operating 870 system platform. 871 872 =head1 Known Problems 873 874 The hash randomisation mentioned in L</Incompatible Changes> is definitely 875 problematic: it will wake dormant bugs and shake out bad assumptions. 876 877 If you want to use mod_perl 2.x with Perl 5.8.1, you will need 878 mod_perl-1.99_10 or higher. Earlier versions of mod_perl 2.x 879 do not work with the randomised hashes. (mod_perl 1.x works fine.) 880 You will also need Apache::Test 1.04 or higher. 881 882 Many of the rarer platforms that worked 100% or pretty close to it 883 with perl 5.8.0 have been left a little bit untended since their 884 maintainers have been otherwise busy lately, and therefore there will 885 be more failures on those platforms. Such platforms include Mac OS 886 Classic, IBM z/OS (and other EBCDIC platforms), and NetWare. The most 887 common Perl platforms (Unix and Unix-like, Microsoft platforms, and 888 VMS) have large enough testing and expert population that they are 889 doing well. 890 891 =head2 Tied hashes in scalar context 892 893 Tied hashes do not currently return anything useful in scalar context, 894 for example when used as boolean tests: 895 896 if (%tied_hash) { ... } 897 898 The current nonsensical behaviour is always to return false, 899 regardless of whether the hash is empty or has elements. 900 901 The root cause is that there is no interface for the implementors of 902 tied hashes to implement the behaviour of a hash in scalar context. 903 904 =head2 Net::Ping 450_service and 510_ping_udp failures 905 906 The subtests 9 and 18 of lib/Net/Ping/t/450_service.t, and the 907 subtest 2 of lib/Net/Ping/t/510_ping_udp.t might fail if you have 908 an unusual networking setup. For example in the latter case the 909 test is trying to send a UDP ping to the IP address 127.0.0.1. 910 911 =head2 B::C 912 913 The C-generating compiler backend B::C (the frontend being 914 C<perlcc -c>) is even more broken than it used to be because of 915 the extensive lexical variable changes. (The good news is that 916 B::Bytecode and ByteLoader are better than they used to be.) 917 918 =head1 Platform Specific Problems 919 920 =head2 EBCDIC Platforms 921 922 IBM z/OS and other EBCDIC platforms continue to be problematic 923 regarding Unicode support. Many Unicode tests are skipped when 924 they really should be fixed. 925 926 =head2 Cygwin 1.5 problems 927 928 In Cygwin 1.5 the F<io/tell> and F<op/sysio> tests have failures for 929 some yet unknown reason. In 1.5.5 the threads tests stress_cv, 930 stress_re, and stress_string are failing unless the environment 931 variable PERLIO is set to "perlio" (which makes also the io/tell 932 failure go away). 933 934 Perl 5.8.1 does build and work well with Cygwin 1.3: with (uname -a) 935 C<CYGWIN_NT-5.0 ... 1.3.22(0.78/3/2) 2003-03-18 09:20 i686 ...> 936 a 100% "make test" was achieved with C<Configure -des -Duseithreads>. 937 938 =head2 HP-UX: HP cc warnings about sendfile and sendpath 939 940 With certain HP C compiler releases (e.g. B.11.11.02) you will 941 get many warnings like this (lines wrapped for easier reading): 942 943 cc: "/usr/include/sys/socket.h", line 504: warning 562: 944 Redeclaration of "sendfile" with a different storage class specifier: 945 "sendfile" will have internal linkage. 946 cc: "/usr/include/sys/socket.h", line 505: warning 562: 947 Redeclaration of "sendpath" with a different storage class specifier: 948 "sendpath" will have internal linkage. 949 950 The warnings show up both during the build of Perl and during certain 951 lib/ExtUtils tests that invoke the C compiler. The warning, however, 952 is not serious and can be ignored. 953 954 =head2 IRIX: t/uni/tr_7jis.t falsely failing 955 956 The test t/uni/tr_7jis.t is known to report failure under 'make test' 957 or the test harness with certain releases of IRIX (at least IRIX 6.5 958 and MIPSpro Compilers Version 7.3.1.1m), but if run manually the test 959 fully passes. 960 961 =head2 Mac OS X: no usemymalloc 962 963 The Perl malloc (C<-Dusemymalloc>) does not work at all in Mac OS X. 964 This is not that serious, though, since the native malloc works just 965 fine. 966 967 =head2 Tru64: No threaded builds with GNU cc (gcc) 968 969 In the latest Tru64 releases (e.g. v5.1B or later) gcc cannot be used 970 to compile a threaded Perl (-Duseithreads) because the system 971 C<< <pthread.h> >> file doesn't know about gcc. 972 973 =head2 Win32: sysopen, sysread, syswrite 974 975 As of the 5.8.0 release, sysopen()/sysread()/syswrite() do not behave 976 like they used to in 5.6.1 and earlier with respect to "text" mode. 977 These built-ins now always operate in "binary" mode (even if sysopen() 978 was passed the O_TEXT flag, or if binmode() was used on the file 979 handle). Note that this issue should only make a difference for disk 980 files, as sockets and pipes have always been in "binary" mode in the 981 Windows port. As this behavior is currently considered a bug, 982 compatible behavior may be re-introduced in a future release. Until 983 then, the use of sysopen(), sysread() and syswrite() is not supported 984 for "text" mode operations. 985 986 =head1 Future Directions 987 988 The following things B<might> happen in future. The first publicly 989 available releases having these characteristics will be the developer 990 releases Perl 5.9.x, culminating in the Perl 5.10.0 release. These 991 are our best guesses at the moment: we reserve the right to rethink. 992 993 =over 4 994 995 =item * 996 997 PerlIO will become The Default. Currently (in Perl 5.8.x) the stdio 998 library is still used if Perl thinks it can use certain tricks to 999 make stdio go B<really> fast. For future releases our goal is to 1000 make PerlIO go even faster. 1001 1002 =item * 1003 1004 A new feature called I<assertions> will be available. This means that 1005 one can have code called assertions sprinkled in the code: usually 1006 they are optimised away, but they can be enabled with the C<-A> option. 1007 1008 =item * 1009 1010 A new operator C<//> (defined-or) will be available. This means that 1011 one will be able to say 1012 1013 $a // $b 1014 1015 instead of 1016 1017 defined $a ? $a : $b 1018 1019 and 1020 1021 $c //= $d; 1022 1023 instead of 1024 1025 $c = $d unless defined $c; 1026 1027 The operator will have the same precedence and associativity as C<||>. 1028 A source code patch against the Perl 5.8.1 sources will be available 1029 in CPAN as F<authors/id/H/HM/HMBRAND/dor-5.8.1.diff>. 1030 1031 =item * 1032 1033 C<unpack()> will default to unpacking the C<$_>. 1034 1035 =item * 1036 1037 Various Copy-On-Write techniques will be investigated in hopes 1038 of speeding up Perl. 1039 1040 =item * 1041 1042 CPANPLUS, Inline, and Module::Build will become core modules. 1043 1044 =item * 1045 1046 The ability to write true lexically scoped pragmas will be introduced. 1047 1048 =item * 1049 1050 Work will continue on the bytecompiler and byteloader. 1051 1052 =item * 1053 1054 v-strings as they currently exist are scheduled to be deprecated. The 1055 v-less form (1.2.3) will become a "version object" when used with C<use>, 1056 C<require>, and C<$VERSION>. $^V will also be a "version object" so the 1057 printf("%vd",...) construct will no longer be needed. The v-ful version 1058 (v1.2.3) will become obsolete. The equivalence of strings and v-strings (e.g. 1059 that currently 5.8.0 is equal to "\5\8\0") will go away. B<There may be no 1060 deprecation warning for v-strings>, though: it is quite hard to detect when 1061 v-strings are being used safely, and when they are not. 1062 1063 =item * 1064 1065 5.005 Threads Will Be Removed 1066 1067 =item * 1068 1069 The C<$*> Variable Will Be Removed 1070 (it was deprecated a long time ago) 1071 1072 =item * 1073 1074 Pseudohashes Will Be Removed 1075 1076 =back 1077 1078 =head1 Reporting Bugs 1079 1080 If you find what you think is a bug, you might check the articles 1081 recently posted to the comp.lang.perl.misc newsgroup and the perl 1082 bug database at http://bugs.perl.org/ . There may also be 1083 information at http://www.perl.com/ , the Perl Home Page. 1084 1085 If you believe you have an unreported bug, please run the B<perlbug> 1086 program included with your release. Be sure to trim your bug down 1087 to a tiny but sufficient test case. Your bug report, along with the 1088 output of C<perl -V>, will be sent off to perlbug@perl.org to be 1089 analysed by the Perl porting team. You can browse and search 1090 the Perl 5 bugs at http://bugs.perl.org/ 1091 1092 =head1 SEE ALSO 1093 1094 The F<Changes> file for exhaustive details on what changed. 1095 1096 The F<INSTALL> file for how to build Perl. 1097 1098 The F<README> file for general stuff. 1099 1100 The F<Artistic> and F<Copying> files for copyright information. 1101 1102 =cut
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