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diff --git a/Master/tlpkg/tlperl.straw/lib/pods/perl58delta.pod b/Master/tlpkg/tlperl.straw/lib/pods/perl58delta.pod new file mode 100755 index 00000000000..6bfdfb670b9 --- /dev/null +++ b/Master/tlpkg/tlperl.straw/lib/pods/perl58delta.pod @@ -0,0 +1,3746 @@ +=head1 NAME + +perl58delta - what is new for perl v5.8.0 + +=head1 DESCRIPTION + +This document describes differences between the 5.6.0 release and +the 5.8.0 release. + +Many of the bug fixes in 5.8.0 were already seen in the 5.6.1 +maintenance release since the two releases were kept closely +coordinated (while 5.8.0 was still called 5.7.something). + +Changes that were integrated into the 5.6.1 release are marked C<[561]>. +Many of these changes have been further developed since 5.6.1 was released, +those are marked C<[561+]>. + +You can see the list of changes in the 5.6.1 release (both from the +5.005_03 release and the 5.6.0 release) by reading L<perl561delta>. + +=head1 Highlights In 5.8.0 + +=over 4 + +=item * + +Better Unicode support + +=item * + +New IO Implementation + +=item * + +New Thread Implementation + +=item * + +Better Numeric Accuracy + +=item * + +Safe Signals + +=item * + +Many New Modules + +=item * + +More Extensive Regression Testing + +=back + +=head1 Incompatible Changes + +=head2 Binary Incompatibility + +B<Perl 5.8 is not binary compatible with earlier releases of Perl.> + +B<You have to recompile your XS modules.> + +(Pure Perl modules should continue to work.) + +The major reason for the discontinuity is the new IO architecture +called PerlIO. PerlIO is the default configuration because without +it many new features of Perl 5.8 cannot be used. In other words: +you just have to recompile your modules containing XS code, sorry +about that. + +In future releases of Perl, non-PerlIO aware XS modules may become +completely unsupported. This shouldn't be too difficult for module +authors, however: PerlIO has been designed as a drop-in replacement +(at the source code level) for the stdio interface. + +Depending on your platform, there are also other reasons why +we decided to break binary compatibility, please read on. + +=head2 64-bit platforms and malloc + +If your pointers are 64 bits wide, the Perl malloc is no longer being +used because it does not work well with 8-byte pointers. Also, +usually the system mallocs on such platforms are much better optimized +for such large memory models than the Perl malloc. Some memory-hungry +Perl applications like the PDL don't work well with Perl's malloc. +Finally, other applications than Perl (such as mod_perl) tend to prefer +the system malloc. Such platforms include Alpha and 64-bit HPPA, +MIPS, PPC, and Sparc. + +=head2 AIX Dynaloading + +The AIX dynaloading now uses in AIX releases 4.3 and newer the native +dlopen interface of AIX instead of the old emulated interface. This +change will probably break backward compatibility with compiled +modules. The change was made to make Perl more compliant with other +applications like mod_perl which are using the AIX native interface. + +=head2 Attributes for C<my> variables now handled at run-time + +The C<my EXPR : ATTRS> syntax now applies variable attributes at +run-time. (Subroutine and C<our> variables still get attributes applied +at compile-time.) See L<attributes> for additional details. In particular, +however, this allows variable attributes to be useful for C<tie> interfaces, +which was a deficiency of earlier releases. Note that the new semantics +doesn't work with the Attribute::Handlers module (as of version 0.76). + +=head2 Socket Extension Dynamic in VMS + +The Socket extension is now dynamically loaded instead of being +statically built in. This may or may not be a problem with ancient +TCP/IP stacks of VMS: we do not know since we weren't able to test +Perl in such configurations. + +=head2 IEEE-format Floating Point Default on OpenVMS Alpha + +Perl now uses IEEE format (T_FLOAT) as the default internal floating +point format on OpenVMS Alpha, potentially breaking binary compatibility +with external libraries or existing data. G_FLOAT is still available as +a configuration option. The default on VAX (D_FLOAT) has not changed. + +=head2 New Unicode Semantics (no more C<use utf8>, almost) + +Previously in Perl 5.6 to use Unicode one would say "use utf8" and +then the operations (like string concatenation) were Unicode-aware +in that lexical scope. + +This was found to be an inconvenient interface, and in Perl 5.8 the +Unicode model has completely changed: now the "Unicodeness" is bound +to the data itself, and for most of the time "use utf8" is not needed +at all. The only remaining use of "use utf8" is when the Perl script +itself has been written in the UTF-8 encoding of Unicode. (UTF-8 has +not been made the default since there are many Perl scripts out there +that are using various national eight-bit character sets, which would +be illegal in UTF-8.) + +See L<perluniintro> for the explanation of the current model, +and L<utf8> for the current use of the utf8 pragma. + +=head2 New Unicode Properties + +Unicode I<scripts> are now supported. Scripts are similar to (and superior +to) Unicode I<blocks>. The difference between scripts and blocks is that +scripts are the glyphs used by a language or a group of languages, while +the blocks are more artificial groupings of (mostly) 256 characters based +on the Unicode numbering. + +In general, scripts are more inclusive, but not universally so. For +example, while the script C<Latin> includes all the Latin characters and +their various diacritic-adorned versions, it does not include the various +punctuation or digits (since they are not solely C<Latin>). + +A number of other properties are now supported, including C<\p{L&}>, +C<\p{Any}> C<\p{Assigned}>, C<\p{Unassigned}>, C<\p{Blank}> [561] and +C<\p{SpacePerl}> [561] (along with their C<\P{...}> versions, of course). +See L<perlunicode> for details, and more additions. + +The C<In> or C<Is> prefix to names used with the C<\p{...}> and C<\P{...}> +are now almost always optional. The only exception is that a C<In> prefix +is required to signify a Unicode block when a block name conflicts with a +script name. For example, C<\p{Tibetan}> refers to the script, while +C<\p{InTibetan}> refers to the block. When there is no name conflict, you +can omit the C<In> from the block name (e.g. C<\p{BraillePatterns}>), but +to be safe, it's probably best to always use the C<In>). + +=head2 REF(...) Instead Of SCALAR(...) + +A reference to a reference now stringifies as "REF(0x81485ec)" instead +of "SCALAR(0x81485ec)" in order to be more consistent with the return +value of ref(). + +=head2 pack/unpack D/F recycled + +The undocumented pack/unpack template letters D/F have been recycled +for better use: now they stand for long double (if supported by the +platform) and NV (Perl internal floating point type). (They used +to be aliases for d/f, but you never knew that.) + +=head2 glob() now returns filenames in alphabetical order + +The list of filenames from glob() (or <...>) is now by default sorted +alphabetically to be csh-compliant (which is what happened before +in most UNIX platforms). (bsd_glob() does still sort platform +natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.) [561] + +=head2 Deprecations + +=over 4 + +=item * + +The semantics of bless(REF, REF) were unclear and until someone proves +it to make some sense, it is forbidden. + +=item * + +The obsolete chat2 library that should never have been allowed +to escape the laboratory has been decommissioned. + +=item * + +Using chdir("") or chdir(undef) instead of explicit chdir() is +doubtful. A failure (think chdir(some_function()) can lead into +unintended chdir() to the home directory, therefore this behaviour +is deprecated. + +=item * + +The builtin dump() function has probably outlived most of its +usefulness. The core-dumping functionality will remain in future +available as an explicit call to C<CORE::dump()>, but in future +releases the behaviour of an unqualified C<dump()> call may change. + +=item * + +The very dusty examples in the eg/ directory have been removed. +Suggestions for new shiny examples welcome but the main issue is that +the examples need to be documented, tested and (most importantly) +maintained. + +=item * + +The (bogus) escape sequences \8 and \9 now give an optional warning +("Unrecognized escape passed through"). There is no need to \-escape +any C<\w> character. + +=item * + +The *glob{FILEHANDLE} is deprecated, use *glob{IO} instead. + +=item * + +The C<package;> syntax (C<package> without an argument) has been +deprecated. Its semantics were never that clear and its +implementation even less so. If you have used that feature to +disallow all but fully qualified variables, C<use strict;> instead. + +=item * + +The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still +recognised but now cause fatal errors. The previous behaviour of +ignoring them by default and warning if requested was unacceptable +since it, in a way, falsely promised that the features could be used. + +=item * + +In future releases, non-PerlIO aware XS modules may become completely +unsupported. Since PerlIO is a drop-in replacement for stdio at the +source code level, this shouldn't be that drastic a change. + +=item * + +Previous versions of perl and some readings of some sections of Camel +III implied that the C<:raw> "discipline" was the inverse of C<:crlf>. +Turning off "clrfness" is no longer enough to make a stream truly +binary. So the PerlIO C<:raw> layer (or "discipline", to use the Camel +book's older terminology) is now formally defined as being equivalent +to binmode(FH) - which is in turn defined as doing whatever is +necessary to pass each byte as-is without any translation. In +particular binmode(FH) - and hence C<:raw> - will now turn off both +CRLF and UTF-8 translation and remove other layers (e.g. :encoding()) +which would modify byte stream. + +=item * + +The current user-visible implementation of pseudo-hashes (the weird +use of the first array element) is deprecated starting from Perl 5.8.0 +and will be removed in Perl 5.10.0, and the feature will be +implemented differently. Not only is the current interface rather +ugly, but the current implementation slows down normal array and hash +use quite noticeably. The C<fields> pragma interface will remain +available. The I<restricted hashes> interface is expected to +be the replacement interface (see L<Hash::Util>). If your existing +programs depends on the underlying implementation, consider using +L<Class::PseudoHash> from CPAN. + +=item * + +The syntaxes C<< @a->[...] >> and C<< %h->{...} >> have now been deprecated. + +=item * + +After years of trying, suidperl is considered to be too complex to +ever be considered truly secure. The suidperl functionality is likely +to be removed in a future release. + +=item * + +The 5.005 threads model (module C<Thread>) is deprecated and expected +to be removed in Perl 5.10. Multithreaded code should be migrated to +the new ithreads model (see L<threads>, L<threads::shared> and +L<perlthrtut>). + +=item * + +The long deprecated uppercase aliases for the string comparison +operators (EQ, NE, LT, LE, GE, GT) have now been removed. + +=item * + +The tr///C and tr///U features have been removed and will not return; +the interface was a mistake. Sorry about that. For similar +functionality, see pack('U0', ...) and pack('C0', ...). [561] + +=item * + +Earlier Perls treated "sub foo (@bar)" as equivalent to "sub foo (@)". +The prototypes are now checked better at compile-time for invalid +syntax. An optional warning is generated ("Illegal character in +prototype...") but this may be upgraded to a fatal error in a future +release. + +=item * + +The C<exec LIST> and C<system LIST> operations now produce warnings on +tainted data and in some future release they will produce fatal errors. + +=item * + +The existing behaviour when localising tied arrays and hashes is wrong, +and will be changed in a future release, so do not rely on the existing +behaviour. See L<"Localising Tied Arrays and Hashes Is Broken">. + +=back + +=head1 Core Enhancements + +=head2 Unicode Overhaul + +Unicode in general should be now much more usable than in Perl 5.6.0 +(or even in 5.6.1). Unicode can be used in hash keys, Unicode in +regular expressions should work now, Unicode in tr/// should work now, +Unicode in I/O should work now. See L<perluniintro> for introduction +and L<perlunicode> for details. + +=over 4 + +=item * + +The Unicode Character Database coming with Perl has been upgraded +to Unicode 3.2.0. For more information, see http://www.unicode.org/ . +[561+] (5.6.1 has UCD 3.0.1.) + +=item * + +For developers interested in enhancing Perl's Unicode capabilities: +almost all the UCD files are included with the Perl distribution in +the F<lib/unicore> subdirectory. The most notable omission, for space +considerations, is the Unihan database. + +=item * + +The properties \p{Blank} and \p{SpacePerl} have been added. "Blank" is like +C isblank(), that is, it contains only "horizontal whitespace" (the space +character is, the newline isn't), and the "SpacePerl" is the Unicode +equivalent of C<\s> (\p{Space} isn't, since that includes the vertical +tabulator character, whereas C<\s> doesn't.) + +See "New Unicode Properties" earlier in this document for additional +information on changes with Unicode properties. + +=back + +=head2 PerlIO is Now The Default + +=over 4 + +=item * + +IO is now by default done via PerlIO rather than system's "stdio". +PerlIO allows "layers" to be "pushed" onto a file handle to alter the +handle's behaviour. Layers can be specified at open time via 3-arg +form of open: + + open($fh,'>:crlf :utf8', $path) || ... + +or on already opened handles via extended C<binmode>: + + binmode($fh,':encoding(iso-8859-7)'); + +The built-in layers are: unix (low level read/write), stdio (as in +previous Perls), perlio (re-implementation of stdio buffering in a +portable manner), crlf (does CRLF <=> "\n" translation as on Win32, +but available on any platform). A mmap layer may be available if +platform supports it (mostly UNIXes). + +Layers to be applied by default may be specified via the 'open' pragma. + +See L</"Installation and Configuration Improvements"> for the effects +of PerlIO on your architecture name. + +=item * + +If your platform supports fork(), you can use the list form of C<open> +for pipes. For example: + + open KID_PS, "-|", "ps", "aux" or die $!; + +forks the ps(1) command (without spawning a shell, as there are more +than three arguments to open()), and reads its standard output via the +C<KID_PS> filehandle. See L<perlipc>. + +=item * + +File handles can be marked as accepting Perl's internal encoding of Unicode +(UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" : + + open($fh,">:utf8","Uni.txt"); + +Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named +for you since it's not UTF-8 what you will be getting but instead +UTF-EBCDIC. See L<perlunicode>, L<utf8>, and +http://www.unicode.org/unicode/reports/tr16/ for more information. +In future releases this naming may change. See L<perluniintro> +for more information about UTF-8. + +=item * + +If your environment variables (LC_ALL, LC_CTYPE, LANG) look like you +want to use UTF-8 (any of the variables match C</utf-?8/i>), your +STDIN, STDOUT, STDERR handles and the default open layer (see L<open>) +are marked as UTF-8. (This feature, like other new features that +combine Unicode and I/O, work only if you are using PerlIO, but that's +the default.) + +Note that after this Perl really does assume that everything is UTF-8: +for example if some input handle is not, Perl will probably very soon +complain about the input data like this "Malformed UTF-8 ..." since +any old eight-bit data is not legal UTF-8. + +Note for code authors: if you want to enable your users to use UTF-8 +as their default encoding but in your code still have eight-bit I/O streams +(such as images or zip files), you need to explicitly open() or binmode() +with C<:bytes> (see L<perlfunc/open> and L<perlfunc/binmode>), or you +can just use C<binmode(FH)> (nice for pre-5.8.0 backward compatibility). + +=item * + +File handles can translate character encodings from/to Perl's internal +Unicode form on read/write via the ":encoding()" layer. + +=item * + +File handles can be opened to "in memory" files held in Perl scalars via: + + open($fh,'>', \$variable) || ... + +=item * + +Anonymous temporary files are available without need to +'use FileHandle' or other module via + + open($fh,"+>", undef) || ... + +That is a literal undef, not an undefined value. + +=back + +=head2 ithreads + +The new interpreter threads ("ithreads" for short) implementation of +multithreading, by Arthur Bergman, replaces the old "5.005 threads" +implementation. In the ithreads model any data sharing between +threads must be explicit, as opposed to the model where data sharing +was implicit. See L<threads> and L<threads::shared>, and +L<perlthrtut>. + +As a part of the ithreads implementation Perl will also use +any necessary and detectable reentrant libc interfaces. + +=head2 Restricted Hashes + +A restricted hash is restricted to a certain set of keys, no keys +outside the set can be added. Also individual keys can be restricted +so that the key cannot be deleted and the value cannot be changed. +No new syntax is involved: the Hash::Util module is the interface. + +=head2 Safe Signals + +Perl used to be fragile in that signals arriving at inopportune moments +could corrupt Perl's internal state. Now Perl postpones handling of +signals until it's safe (between opcodes). + +This change may have surprising side effects because signals no longer +interrupt Perl instantly. Perl will now first finish whatever it was +doing, like finishing an internal operation (like sort()) or an +external operation (like an I/O operation), and only then look at any +arrived signals (and before starting the next operation). No more corrupt +internal state since the current operation is always finished first, +but the signal may take more time to get heard. Note that breaking +out from potentially blocking operations should still work, though. + +=head2 Understanding of Numbers + +In general a lot of fixing has happened in the area of Perl's +understanding of numbers, both integer and floating point. Since in +many systems the standard number parsing functions like C<strtoul()> +and C<atof()> seem to have bugs, Perl tries to work around their +deficiencies. This results hopefully in more accurate numbers. + +Perl now tries internally to use integer values in numeric conversions +and basic arithmetics (+ - * /) if the arguments are integers, and +tries also to keep the results stored internally as integers. +This change leads to often slightly faster and always less lossy +arithmetics. (Previously Perl always preferred floating point numbers +in its math.) + +=head2 Arrays now always interpolate into double-quoted strings [561] + +In double-quoted strings, arrays now interpolate, no matter what. The +behavior in earlier versions of perl 5 was that arrays would interpolate +into strings if the array had been mentioned before the string was +compiled, and otherwise Perl would raise a fatal compile-time error. +In versions 5.000 through 5.003, the error was + + Literal @example now requires backslash + +In versions 5.004_01 through 5.6.0, the error was + + In string, @example now must be written as \@example + +The idea here was to get people into the habit of writing +C<"fred\@example.com"> when they wanted a literal C<@> sign, just as +they have always written C<"Give me back my \$5"> when they wanted a +literal C<$> sign. + +Starting with 5.6.1, when Perl now sees an C<@> sign in a +double-quoted string, it I<always> attempts to interpolate an array, +regardless of whether or not the array has been used or declared +already. The fatal error has been downgraded to an optional warning: + + Possible unintended interpolation of @example in string + +This warns you that C<"fred@example.com"> is going to turn into +C<fred.com> if you don't backslash the C<@>. +See http://www.plover.com/~mjd/perl/at-error.html for more details +about the history here. + +=head2 Miscellaneous Changes + +=over 4 + +=item * + +AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute +to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value. + +=item * + +The $Config{byteorder} (and corresponding BYTEORDER in config.h) was +previously wrong in platforms if sizeof(long) was 4, but sizeof(IV) +was 8. The byteorder was only sizeof(long) bytes long (1234 or 4321), +but now it is correctly sizeof(IV) bytes long, (12345678 or 87654321). +(This problem didn't affect Windows platforms.) + +Also, $Config{byteorder} is now computed dynamically--this is more +robust with "fat binaries" where an executable image contains binaries +for more than one binary platform, and when cross-compiling. + +=item * + +C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass +in multiple arguments.) + +=item * + +C<do> followed by a bareword now ensures that this bareword isn't +a keyword (to avoid a bug where C<do q(foo.pl)> tried to call a +subroutine called C<q>). This means that for example instead of +C<do format()> you must write C<do &format()>. + +=item * + +The builtin dump() now gives an optional warning +C<dump() better written as CORE::dump()>, +meaning that by default C<dump(...)> is resolved as the builtin +dump() which dumps core and aborts, not as (possibly) user-defined +C<sub dump>. To call the latter, qualify the call as C<&dump(...)>. +(The whole dump() feature is to considered deprecated, and possibly +removed/changed in future releases.) + +=item * + +chomp() and chop() are now overridable. Note, however, that their +prototype (as given by C<prototype("CORE::chomp")> is undefined, +because it cannot be expressed and therefore one cannot really write +replacements to override these builtins. + +=item * + +END blocks are now run even if you exit/die in a BEGIN block. +Internally, the execution of END blocks is now controlled by +PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new +behaviour for Perl embedders. This will default in 5.10. See +L<perlembed>. + +=item * + +Formats now support zero-padded decimal fields. + +=item * + +Although "you shouldn't do that", it was possible to write code that +depends on Perl's hashed key order (Data::Dumper does this). The new +algorithm "One-at-a-Time" produces a different hashed key order. +More details are in L</"Performance Enhancements">. + +=item * + +lstat(FILEHANDLE) now gives a warning because the operation makes no sense. +In future releases this may become a fatal error. + +=item * + +Spurious syntax errors generated in certain situations, when glob() +caused File::Glob to be loaded for the first time, have been fixed. [561] + +=item * + +Lvalue subroutines can now return C<undef> in list context. However, +the lvalue subroutine feature still remains experimental. [561+] + +=item * + +A lost warning "Can't declare ... dereference in my" has been +restored (Perl had it earlier but it became lost in later releases.) + +=item * + +A new special regular expression variable has been introduced: +C<$^N>, which contains the most-recently closed group (submatch). + +=item * + +C<no Module;> does not produce an error even if Module does not have an +unimport() method. This parallels the behavior of C<use> vis-a-vis +C<import>. [561] + +=item * + +The numerical comparison operators return C<undef> if either operand +is a NaN. Previously the behaviour was unspecified. + +=item * + +C<our> can now have an experimental optional attribute C<unique> that +affects how global variables are shared among multiple interpreters, +see L<perlfunc/our>. + +=item * + +The following builtin functions are now overridable: each(), keys(), +pop(), push(), shift(), splice(), unshift(). [561] + +=item * + +C<pack() / unpack()> can now group template letters with C<()> and then +apply repetition/count modifiers on the groups. + +=item * + +C<pack() / unpack()> can now process the Perl internal numeric types: +IVs, UVs, NVs-- and also long doubles, if supported by the platform. +The template letters are C<j>, C<J>, C<F>, and C<D>. + +=item * + +C<pack('U0a*', ...)> can now be used to force a string to UTF-8. + +=item * + +my __PACKAGE__ $obj now works. [561] + +=item * + +POSIX::sleep() now returns the number of I<unslept> seconds +(as the POSIX standard says), as opposed to CORE::sleep() which +returns the number of slept seconds. + +=item * + +printf() and sprintf() now support parameter reordering using the +C<%\d+\$> and C<*\d+\$> syntaxes. For example + + printf "%2\$s %1\$s\n", "foo", "bar"; + +will print "bar foo\n". This feature helps in writing +internationalised software, and in general when the order +of the parameters can vary. + +=item * + +The (\&) prototype now works properly. [561] + +=item * + +prototype(\[$@%&]) is now available to implicitly create references +(useful for example if you want to emulate the tie() interface). + +=item * + +A new command-line option, C<-t> is available. It is the +little brother of C<-T>: instead of dying on taint violations, +lexical warnings are given. B<This is only meant as a temporary +debugging aid while securing the code of old legacy applications. +This is not a substitute for -T.> + +=item * + +In other taint news, the C<exec LIST> and C<system LIST> have now been +considered too risky (think C<exec @ARGV>: it can start any program +with any arguments), and now the said forms cause a warning under +lexical warnings. You should carefully launder the arguments to +guarantee their validity. In future releases of Perl the forms will +become fatal errors so consider starting laundering now. + +=item * + +Tied hash interfaces are now required to have the EXISTS and DELETE +methods (either own or inherited). + +=item * + +If tr/// is just counting characters, it doesn't attempt to +modify its target. + +=item * + +untie() will now call an UNTIE() hook if it exists. See L<perltie> +for details. [561] + +=item * + +L<utime> now supports C<utime undef, undef, @files> to change the +file timestamps to the current time. + +=item * + +The rules for allowing underscores (underbars) in numeric constants +have been relaxed and simplified: now you can have an underscore +simply B<between digits>. + +=item * + +Rather than relying on C's argv[0] (which may not contain a full pathname) +where possible $^X is now set by asking the operating system. +(eg by reading F</proc/self/exe> on Linux, F</proc/curproc/file> on FreeBSD) + +=item * + +A new variable, C<${^TAINT}>, indicates whether taint mode is enabled. + +=item * + +You can now override the readline() builtin, and this overrides also +the <FILEHANDLE> angle bracket operator. + +=item * + +The command-line options -s and -F are now recognized on the shebang +(#!) line. + +=item * + +Use of the C</c> match modifier without an accompanying C</g> modifier +elicits a new warning: C<Use of /c modifier is meaningless without /g>. + +Use of C</c> in substitutions, even with C</g>, elicits +C<Use of /c modifier is meaningless in s///>. + +Use of C</g> with C<split> elicits C<Use of /g modifier is meaningless +in split>. + +=item * + +Support for the C<CLONE> special subroutine had been added. +With ithreads, when a new thread is created, all Perl data is cloned, +however non-Perl data cannot be cloned automatically. In C<CLONE> you +can do whatever you need to do, like for example handle the cloning of +non-Perl data, if necessary. C<CLONE> will be executed once for every +package that has it defined or inherited. It will be called in the +context of the new thread, so all modifications are made in the new area. + +See L<perlmod> + +=back + +=head1 Modules and Pragmata + +=head2 New Modules and Pragmata + +=over 4 + +=item * + +C<Attribute::Handlers>, originally by Damian Conway and now maintained +by Arthur Bergman, allows a class to define attribute handlers. + + package MyPack; + use Attribute::Handlers; + sub Wolf :ATTR(SCALAR) { print "howl!\n" } + + # later, in some package using or inheriting from MyPack... + + my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called + +Both variables and routines can have attribute handlers. Handlers can +be specific to type (SCALAR, ARRAY, HASH, or CODE), or specific to the +exact compilation phase (BEGIN, CHECK, INIT, or END). +See L<Attribute::Handlers>. + +=item * + +C<B::Concise>, by Stephen McCamant, is a new compiler backend for +walking the Perl syntax tree, printing concise info about ops. +The output is highly customisable. See L<B::Concise>. [561+] + +=item * + +The new bignum, bigint, and bigrat pragmas, by Tels, implement +transparent bignum support (using the Math::BigInt, Math::BigFloat, +and Math::BigRat backends). + +=item * + +C<Class::ISA>, by Sean Burke, is a module for reporting the search +path for a class's ISA tree. See L<Class::ISA>. + +=item * + +C<Cwd> now has a split personality: if possible, an XS extension is +used, (this will hopefully be faster, more secure, and more robust) +but if not possible, the familiar Perl implementation is used. + +=item * + +C<Devel::PPPort>, originally by Kenneth Albanowski and now +maintained by Paul Marquess, has been added. It is primarily used +by C<h2xs> to enhance portability of XS modules between different +versions of Perl. See L<Devel::PPPort>. + +=item * + +C<Digest>, frontend module for calculating digests (checksums), from +Gisle Aas, has been added. See L<Digest>. + +=item * + +C<Digest::MD5> for calculating MD5 digests (checksums) as defined in +RFC 1321, from Gisle Aas, has been added. See L<Digest::MD5>. + + use Digest::MD5 'md5_hex'; + + $digest = md5_hex("Thirsty Camel"); + + print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1 + +NOTE: the C<MD5> backward compatibility module is deliberately not +included since its further use is discouraged. + +See also L<PerlIO::via::QuotedPrint>. + +=item * + +C<Encode>, originally by Nick Ing-Simmons and now maintained by Dan +Kogai, provides a mechanism to translate between different character +encodings. Support for Unicode, ISO-8859-1, and ASCII are compiled in +to the module. Several other encodings (like the rest of the +ISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC, Chinese, +Japanese, and Korean encodings) are included and can be loaded at +runtime. (For space considerations, the largest Chinese encodings +have been separated into their own CPAN module, Encode::HanExtra, +which Encode will use if available). See L<Encode>. + +Any encoding supported by Encode module is also available to the +":encoding()" layer if PerlIO is used. + +=item * + +C<Hash::Util> is the interface to the new I<restricted hashes> +feature. (Implemented by Jeffrey Friedl, Nick Ing-Simmons, and +Michael Schwern.) See L<Hash::Util>. + +=item * + +C<I18N::Langinfo> can be used to query locale information. +See L<I18N::Langinfo>. + +=item * + +C<I18N::LangTags>, by Sean Burke, has functions for dealing with +RFC3066-style language tags. See L<I18N::LangTags>. + +=item * + +C<ExtUtils::Constant>, by Nicholas Clark, is a new tool for extension +writers for generating XS code to import C header constants. +See L<ExtUtils::Constant>. + +=item * + +C<Filter::Simple>, by Damian Conway, is an easy-to-use frontend to +Filter::Util::Call. See L<Filter::Simple>. + + # in MyFilter.pm: + + package MyFilter; + + use Filter::Simple sub { + while (my ($from, $to) = splice @_, 0, 2) { + s/$from/$to/g; + } + }; + + 1; + + # in user's code: + + use MyFilter qr/red/ => 'green'; + + print "red\n"; # this code is filtered, will print "green\n" + print "bored\n"; # this code is filtered, will print "bogreen\n" + + no MyFilter; + + print "red\n"; # this code is not filtered, will print "red\n" + +=item * + +C<File::Temp>, by Tim Jenness, allows one to create temporary files +and directories in an easy, portable, and secure way. See L<File::Temp>. +[561+] + +=item * + +C<Filter::Util::Call>, by Paul Marquess, provides you with the +framework to write I<source filters> in Perl. For most uses, the +frontend Filter::Simple is to be preferred. See L<Filter::Util::Call>. + +=item * + +C<if>, by Ilya Zakharevich, is a new pragma for conditional inclusion +of modules. + +=item * + +L<libnet>, by Graham Barr, is a collection of perl5 modules related +to network programming. See L<Net::FTP>, L<Net::NNTP>, L<Net::Ping> +(not part of libnet, but related), L<Net::POP3>, L<Net::SMTP>, +and L<Net::Time>. + +Perl installation leaves libnet unconfigured; use F<libnetcfg> +to configure it. + +=item * + +C<List::Util>, by Graham Barr, is a selection of general-utility +list subroutines, such as sum(), min(), first(), and shuffle(). +See L<List::Util>. + +=item * + +C<Locale::Constants>, C<Locale::Country>, C<Locale::Currency> +C<Locale::Language>, and L<Locale::Script>, by Neil Bowers, have +been added. They provide the codes for various locale standards, such +as "fr" for France, "usd" for US Dollar, and "ja" for Japanese. + + use Locale::Country; + + $country = code2country('jp'); # $country gets 'Japan' + $code = country2code('Norway'); # $code gets 'no' + +See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>, +and L<Locale::Language>. + +=item * + +C<Locale::Maketext>, by Sean Burke, is a localization framework. See +L<Locale::Maketext>, and L<Locale::Maketext::TPJ13>. The latter is an +article about software localization, originally published in The Perl +Journal #13, and republished here with kind permission. + +=item * + +C<Math::BigRat> for big rational numbers, to accompany Math::BigInt and +Math::BigFloat, from Tels. See L<Math::BigRat>. + +=item * + +C<Memoize> can make your functions faster by trading space for time, +from Mark-Jason Dominus. See L<Memoize>. + +=item * + +C<MIME::Base64>, by Gisle Aas, allows you to encode data in base64, +as defined in RFC 2045 - I<MIME (Multipurpose Internet Mail +Extensions)>. + + use MIME::Base64; + + $encoded = encode_base64('Aladdin:open sesame'); + $decoded = decode_base64($encoded); + + print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ==" + +See L<MIME::Base64>. + +=item * + +C<MIME::QuotedPrint>, by Gisle Aas, allows you to encode data +in quoted-printable encoding, as defined in RFC 2045 - I<MIME +(Multipurpose Internet Mail Extensions)>. + + use MIME::QuotedPrint; + + $encoded = encode_qp("\xDE\xAD\xBE\xEF"); + $decoded = decode_qp($encoded); + + print $encoded, "\n"; # "=DE=AD=BE=EF\n" + print $decoded, "\n"; # "\xDE\xAD\xBE\xEF\n" + +See also L<PerlIO::via::QuotedPrint>. + +=item * + +C<NEXT>, by Damian Conway, is a pseudo-class for method redispatch. +See L<NEXT>. + +=item * + +C<open> is a new pragma for setting the default I/O layers +for open(). + +=item * + +C<PerlIO::scalar>, by Nick Ing-Simmons, provides the implementation +of IO to "in memory" Perl scalars as discussed above. It also serves +as an example of a loadable PerlIO layer. Other future possibilities +include PerlIO::Array and PerlIO::Code. See L<PerlIO::scalar>. + +=item * + +C<PerlIO::via>, by Nick Ing-Simmons, acts as a PerlIO layer and wraps +PerlIO layer functionality provided by a class (typically implemented +in Perl code). + +=item * + +C<PerlIO::via::QuotedPrint>, by Elizabeth Mattijsen, is an example +of a C<PerlIO::via> class: + + use PerlIO::via::QuotedPrint; + open($fh,">:via(QuotedPrint)",$path); + +This will automatically convert everything output to C<$fh> to +Quoted-Printable. See L<PerlIO::via> and L<PerlIO::via::QuotedPrint>. + +=item * + +C<Pod::ParseLink>, by Russ Allbery, has been added, +to parse LZ<><> links in pods as described in the new +perlpodspec. + +=item * + +C<Pod::Text::Overstrike>, by Joe Smith, has been added. +It converts POD data to formatted overstrike text. +See L<Pod::Text::Overstrike>. [561+] + +=item * + +C<Scalar::Util> is a selection of general-utility scalar subroutines, +such as blessed(), reftype(), and tainted(). See L<Scalar::Util>. + +=item * + +C<sort> is a new pragma for controlling the behaviour of sort(). + +=item * + +C<Storable> gives persistence to Perl data structures by allowing the +storage and retrieval of Perl data to and from files in a fast and +compact binary format. Because in effect Storable does serialisation +of Perl data structures, with it you can also clone deep, hierarchical +datastructures. Storable was originally created by Raphael Manfredi, +but it is now maintained by Abhijit Menon-Sen. Storable has been +enhanced to understand the two new hash features, Unicode keys and +restricted hashes. See L<Storable>. + +=item * + +C<Switch>, by Damian Conway, has been added. Just by saying + + use Switch; + +you have C<switch> and C<case> available in Perl. + + use Switch; + + switch ($val) { + + case 1 { print "number 1" } + case "a" { print "string a" } + case [1..10,42] { print "number in list" } + case (@array) { print "number in list" } + case /\w+/ { print "pattern" } + case qr/\w+/ { print "pattern" } + case (%hash) { print "entry in hash" } + case (\%hash) { print "entry in hash" } + case (\&sub) { print "arg to subroutine" } + else { print "previous case not true" } + } + +See L<Switch>. + +=item * + +C<Test::More>, by Michael Schwern, is yet another framework for writing +test scripts, more extensive than Test::Simple. See L<Test::More>. + +=item * + +C<Test::Simple>, by Michael Schwern, has basic utilities for writing +tests. See L<Test::Simple>. + +=item * + +C<Text::Balanced>, by Damian Conway, has been added, for extracting +delimited text sequences from strings. + + use Text::Balanced 'extract_delimited'; + + ($a, $b) = extract_delimited("'never say never', he never said", "'", ''); + +$a will be "'never say never'", $b will be ', he never said'. + +In addition to extract_delimited(), there are also extract_bracketed(), +extract_quotelike(), extract_codeblock(), extract_variable(), +extract_tagged(), extract_multiple(), gen_delimited_pat(), and +gen_extract_tagged(). With these, you can implement rather advanced +parsing algorithms. See L<Text::Balanced>. + +=item * + +C<threads>, by Arthur Bergman, is an interface to interpreter threads. +Interpreter threads (ithreads) is the new thread model introduced in +Perl 5.6 but only available as an internal interface for extension +writers (and for Win32 Perl for C<fork()> emulation). See L<threads>, +L<threads::shared>, and L<perlthrtut>. + +=item * + +C<threads::shared>, by Arthur Bergman, allows data sharing for +interpreter threads. See L<threads::shared>. + +=item * + +C<Tie::File>, by Mark-Jason Dominus, associates a Perl array with the +lines of a file. See L<Tie::File>. + +=item * + +C<Tie::Memoize>, by Ilya Zakharevich, provides on-demand loaded hashes. +See L<Tie::Memoize>. + +=item * + +C<Tie::RefHash::Nestable>, by Edward Avis, allows storing hash +references (unlike the standard Tie::RefHash) The module is contained +within Tie::RefHash. See L<Tie::RefHash>. + +=item * + +C<Time::HiRes>, by Douglas E. Wegscheid, provides high resolution +timing (ualarm, usleep, and gettimeofday). See L<Time::HiRes>. + +=item * + +C<Unicode::UCD> offers a querying interface to the Unicode Character +Database. See L<Unicode::UCD>. + +=item * + +C<Unicode::Collate>, by SADAHIRO Tomoyuki, implements the UCA +(Unicode Collation Algorithm) for sorting Unicode strings. +See L<Unicode::Collate>. + +=item * + +C<Unicode::Normalize>, by SADAHIRO Tomoyuki, implements the various +Unicode normalization forms. See L<Unicode::Normalize>. + +=item * + +C<XS::APItest>, by Tim Jenness, is a test extension that exercises XS +APIs. Currently only C<printf()> is tested: how to output various +basic data types from XS. + +=item * + +C<XS::Typemap>, by Tim Jenness, is a test extension that exercises +XS typemaps. Nothing gets installed, but the code is worth studying +for extension writers. + +=back + +=head2 Updated And Improved Modules and Pragmata + +=over 4 + +=item * + +The following independently supported modules have been updated to the +newest versions from CPAN: CGI, CPAN, DB_File, File::Spec, File::Temp, +Getopt::Long, Math::BigFloat, Math::BigInt, the podlators bundle +(Pod::Man, Pod::Text), Pod::LaTeX [561+], Pod::Parser, Storable, +Term::ANSIColor, Test, Text-Tabs+Wrap. + +=item * + +attributes::reftype() now works on tied arguments. + +=item * + +AutoLoader can now be disabled with C<no AutoLoader;>. + +=item * + +B::Deparse has been significantly enhanced by Robin Houston. It can +now deparse almost all of the standard test suite (so that the tests +still succeed). There is a make target "test.deparse" for trying this +out. + +=item * + +Carp now has better interface documentation, and the @CARP_NOT +interface has been added to get optional control over where errors +are reported independently of @ISA, by Ben Tilly. + +=item * + +Class::Struct can now define the classes in compile time. + +=item * + +Class::Struct now assigns the array/hash element if the accessor +is called with an array/hash element as the B<sole> argument. + +=item * + +The return value of Cwd::fastcwd() is now tainted. + +=item * + +Data::Dumper now has an option to sort hashes. + +=item * + +Data::Dumper now has an option to dump code references +using B::Deparse. + +=item * + +DB_File now supports newer Berkeley DB versions, among +other improvements. + +=item * + +Devel::Peek now has an interface for the Perl memory statistics +(this works only if you are using perl's malloc, and if you have +compiled with debugging). + +=item * + +The English module can now be used without the infamous performance +hit by saying + + use English '-no_match_vars'; + +(Assuming, of course, that you don't need the troublesome variables +C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and +C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>. + +=item * + +ExtUtils::MakeMaker has been significantly cleaned up and fixed. +The enhanced version has also been backported to earlier releases +of Perl and submitted to CPAN so that the earlier releases can +enjoy the fixes. + +=item * + +The arguments of WriteMakefile() in Makefile.PL are now checked +for sanity much more carefully than before. This may cause new +warnings when modules are being installed. See L<ExtUtils::MakeMaker> +for more details. + +=item * + +ExtUtils::MakeMaker now uses File::Spec internally, which hopefully +leads to better portability. + +=item * + +Fcntl, Socket, and Sys::Syslog have been rewritten by Nicholas Clark +to use the new-style constant dispatch section (see L<ExtUtils::Constant>). +This means that they will be more robust and hopefully faster. + +=item * + +File::Find now chdir()s correctly when chasing symbolic links. [561] + +=item * + +File::Find now has pre- and post-processing callbacks. It also +correctly changes directories when chasing symbolic links. Callbacks +(naughtily) exiting with "next;" instead of "return;" now work. + +=item * + +File::Find is now (again) reentrant. It also has been made +more portable. + +=item * + +The warnings issued by File::Find now belong to their own category. +You can enable/disable them with C<use/no warnings 'File::Find';>. + +=item * + +File::Glob::glob() has been renamed to File::Glob::bsd_glob() +because the name clashes with the builtin glob(). The older +name is still available for compatibility, but is deprecated. [561] + +=item * + +File::Glob now supports C<GLOB_LIMIT> constant to limit the size of +the returned list of filenames. + +=item * + +IPC::Open3 now allows the use of numeric file descriptors. + +=item * + +IO::Socket now has an atmark() method, which returns true if the socket +is positioned at the out-of-band mark. The method is also exportable +as a sockatmark() function. + +=item * + +IO::Socket::INET failed to open the specified port if the service name +was not known. It now correctly uses the supplied port number as is. [561] + +=item * + +IO::Socket::INET has support for the ReusePort option (if your +platform supports it). The Reuse option now has an alias, ReuseAddr. +For clarity, you may want to prefer ReuseAddr. + +=item * + +IO::Socket::INET now supports a value of zero for C<LocalPort> +(usually meaning that the operating system will make one up.) + +=item * + +'use lib' now works identically to @INC. Removing directories +with 'no lib' now works. + +=item * + +Math::BigFloat and Math::BigInt have undergone a full rewrite by Tels. +They are now magnitudes faster, and they support various bignum +libraries such as GMP and PARI as their backends. + +=item * + +Math::Complex handles inf, NaN etc., better. + +=item * + +Net::Ping has been considerably enhanced by Rob Brown: multihoming is +now supported, Win32 functionality is better, there is now time +measuring functionality (optionally high-resolution using +Time::HiRes), and there is now "external" protocol which uses +Net::Ping::External module which runs your external ping utility and +parses the output. A version of Net::Ping::External is available in +CPAN. + +Note that some of the Net::Ping tests are disabled when running +under the Perl distribution since one cannot assume one or more +of the following: enabled echo port at localhost, full Internet +connectivity, or sympathetic firewalls. You can set the environment +variable PERL_TEST_Net_Ping to "1" (one) before running the Perl test +suite to enable all the Net::Ping tests. + +=item * + +POSIX::sigaction() is now much more flexible and robust. +You can now install coderef handlers, 'DEFAULT', and 'IGNORE' +handlers, installing new handlers was not atomic. + +=item * + +In Safe, C<%INC> is now localised in a Safe compartment so that +use/require work. + +=item * + +In SDBM_File on dosish platforms, some keys went missing because of +lack of support for files with "holes". A workaround for the problem +has been added. + +=item * + +In Search::Dict one can now have a pre-processing hook for the +lines being searched. + +=item * + +The Shell module now has an OO interface. + +=item * + +In Sys::Syslog there is now a failover mechanism that will go +through alternative connection mechanisms until the message +is successfully logged. + +=item * + +The Test module has been significantly enhanced. + +=item * + +Time::Local::timelocal() does not handle fractional seconds anymore. +The rationale is that neither does localtime(), and timelocal() and +localtime() are supposed to be inverses of each other. + +=item * + +The vars pragma now supports declaring fully qualified variables. +(Something that C<our()> does not and will not support.) + +=item * + +The C<utf8::> name space (as in the pragma) provides various +Perl-callable functions to provide low level access to Perl's +internal Unicode representation. At the moment only length() +has been implemented. + +=back + +=head1 Utility Changes + +=over 4 + +=item * + +Emacs perl mode (emacs/cperl-mode.el) has been updated to version +4.31. + +=item * + +F<emacs/e2ctags.pl> is now much faster. + +=item * + +C<enc2xs> is a tool for people adding their own encodings to the +Encode module. + +=item * + +C<h2ph> now supports C trigraphs. + +=item * + +C<h2xs> now produces a template README. + +=item * + +C<h2xs> now uses C<Devel::PPPort> for better portability between +different versions of Perl. + +=item * + +C<h2xs> uses the new L<ExtUtils::Constant|ExtUtils::Constant> module +which will affect newly created extensions that define constants. +Since the new code is more correct (if you have two constants where the +first one is a prefix of the second one, the first constant B<never> +got defined), less lossy (it uses integers for integer constant, +as opposed to the old code that used floating point numbers even for +integer constants), and slightly faster, you might want to consider +regenerating your extension code (the new scheme makes regenerating +easy). L<h2xs> now also supports C trigraphs. + +=item * + +C<libnetcfg> has been added to configure libnet. + +=item * + +C<perlbug> is now much more robust. It also sends the bug report to +perl.org, not perl.com. + +=item * + +C<perlcc> has been rewritten and its user interface (that is, +command line) is much more like that of the UNIX C compiler, cc. +(The perlbc tools has been removed. Use C<perlcc -B> instead.) +B<Note that perlcc is still considered very experimental and +unsupported.> [561] + +=item * + +C<perlivp> is a new Installation Verification Procedure utility +for running any time after installing Perl. + +=item * + +C<piconv> is an implementation of the character conversion utility +C<iconv>, demonstrating the new Encode module. + +=item * + +C<pod2html> now allows specifying a cache directory. + +=item * + +C<pod2html> now produces XHTML 1.0. + +=item * + +C<pod2html> now understands POD written using different line endings +(PC-like CRLF versus UNIX-like LF versus MacClassic-like CR). + +=item * + +C<s2p> has been completely rewritten in Perl. (It is in fact a full +implementation of sed in Perl: you can use the sed functionality by +using the C<psed> utility.) + +=item * + +C<xsubpp> now understands POD documentation embedded in the *.xs +files. [561] + +=item * + +C<xsubpp> now supports the OUT keyword. + +=back + +=head1 New Documentation + +=over 4 + +=item * + +perl56delta details the changes between the 5.005 release and the +5.6.0 release. + +=item * + +perlclib documents the internal replacements for standard C library +functions. (Interesting only for extension writers and Perl core +hackers.) [561+] + +=item * + +perldebtut is a Perl debugging tutorial. [561+] + +=item * + +perlebcdic contains considerations for running Perl on EBCDIC +platforms. [561+] + +=item * + +perlintro is a gentle introduction to Perl. + +=item * + +perliol documents the internals of PerlIO with layers. + +=item * + +perlmodstyle is a style guide for writing modules. + +=item * + +perlnewmod tells about writing and submitting a new module. [561+] + +=item * + +perlpacktut is a pack() tutorial. + +=item * + +perlpod has been rewritten to be clearer and to record the best +practices gathered over the years. + +=item * + +perlpodspec is a more formal specification of the pod format, +mainly of interest for writers of pod applications, not to +people writing in pod. + +=item * + +perlretut is a regular expression tutorial. [561+] + +=item * + +perlrequick is a regular expressions quick-start guide. +Yes, much quicker than perlretut. [561] + +=item * + +perltodo has been updated. + +=item * + +perltootc has been renamed as perltooc (to not to conflict +with perltoot in filesystems restricted to "8.3" names). + +=item * + +perluniintro is an introduction to using Unicode in Perl. +(perlunicode is more of a detailed reference and background +information) + +=item * + +perlutil explains the command line utilities packaged with the Perl +distribution. [561+] + +=back + +The following platform-specific documents are available before +the installation as README.I<platform>, and after the installation +as perlI<platform>: + + perlaix perlamiga perlapollo perlbeos perlbs2000 + perlce perlcygwin perldgux perldos perlepoc perlfreebsd perlhpux + perlhurd perlirix perlmachten perlmacos perlmint perlmpeix + perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris + perltru64 perluts perlvmesa perlvms perlvos perlwin32 + +These documents usually detail one or more of the following subjects: +configuring, building, testing, installing, and sometimes also using +Perl on the said platform. + +Eastern Asian Perl users are now welcomed in their own languages: +README.jp (Japanese), README.ko (Korean), README.cn (simplified +Chinese) and README.tw (traditional Chinese), which are written in +normal pod but encoded in EUC-JP, EUC-KR, EUC-CN and Big5. These +will get installed as + + perljp perlko perlcn perltw + +=over 4 + +=item * + +The documentation for the POSIX-BC platform is called "BS2000", to avoid +confusion with the Perl POSIX module. + +=item * + +The documentation for the WinCE platform is called perlce (README.ce +in the source code kit), to avoid confusion with the perlwin32 +documentation on 8.3-restricted filesystems. + +=back + +=head1 Performance Enhancements + +=over 4 + +=item * + +map() could get pathologically slow when the result list it generates +is larger than the source list. The performance has been improved for +common scenarios. [561] + +=item * + +sort() is also fully reentrant, in the sense that the sort function +can itself call sort(). This did not work reliably in previous +releases. [561] + +=item * + +sort() has been changed to use primarily mergesort internally as +opposed to the earlier quicksort. For very small lists this may +result in slightly slower sorting times, but in general the speedup +should be at least 20%. Additional bonuses are that the worst case +behaviour of sort() is now better (in computer science terms it now +runs in time O(N log N), as opposed to quicksort's Theta(N**2) +worst-case run time behaviour), and that sort() is now stable +(meaning that elements with identical keys will stay ordered as they +were before the sort). See the C<sort> pragma for information. + +The story in more detail: suppose you want to serve yourself a little +slice of Pi. + + @digits = ( 3,1,4,1,5,9 ); + +A numerical sort of the digits will yield (1,1,3,4,5,9), as expected. +Which C<1> comes first is hard to know, since one C<1> looks pretty +much like any other. You can regard this as totally trivial, +or somewhat profound. However, if you just want to sort the even +digits ahead of the odd ones, then what will + + sort { ($a % 2) <=> ($b % 2) } @digits; + +yield? The only even digit, C<4>, will come first. But how about +the odd numbers, which all compare equal? With the quicksort algorithm +used to implement Perl 5.6 and earlier, the order of ties is left up +to the sort. So, as you add more and more digits of Pi, the order +in which the sorted even and odd digits appear will change. +and, for sufficiently large slices of Pi, the quicksort algorithm +in Perl 5.8 won't return the same results even if reinvoked with the +same input. The justification for this rests with quicksort's +worst case behavior. If you run + + sort { $a <=> $b } ( 1 .. $N , 1 .. $N ); + +(something you might approximate if you wanted to merge two sorted +arrays using sort), doubling $N doesn't just double the quicksort time, +it I<quadruples> it. Quicksort has a worst case run time that can +grow like N**2, so-called I<quadratic> behaviour, and it can happen +on patterns that may well arise in normal use. You won't notice this +for small arrays, but you I<will> notice it with larger arrays, +and you may not live long enough for the sort to complete on arrays +of a million elements. So the 5.8 quicksort scrambles large arrays +before sorting them, as a statistical defence against quadratic behaviour. +But that means if you sort the same large array twice, ties may be +broken in different ways. + +Because of the unpredictability of tie-breaking order, and the quadratic +worst-case behaviour, quicksort was I<almost> replaced completely with +a stable mergesort. I<Stable> means that ties are broken to preserve +the original order of appearance in the input array. So + + sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9); + +will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers +appear in the output in the same order they appeared in the input. +Mergesort has worst case O(N log N) behaviour, the best value +attainable. And, ironically, this mergesort does particularly +well where quicksort goes quadratic: mergesort sorts (1..$N, 1..$N) +in O(N) time. But quicksort was rescued at the last moment because +it is faster than mergesort on certain inputs and platforms. +For example, if you really I<don't> care about the order of even +and odd digits, quicksort will run in O(N) time; it's very good +at sorting many repetitions of a small number of distinct elements. +The quicksort divide and conquer strategy works well on platforms +with relatively small, very fast, caches. Eventually, the problem gets +whittled down to one that fits in the cache, from which point it +benefits from the increased memory speed. + +Quicksort was rescued by implementing a sort pragma to control aspects +of the sort. The B<stable> subpragma forces stable behaviour, +regardless of algorithm. The B<_quicksort> and B<_mergesort> +subpragmas are heavy-handed ways to select the underlying implementation. +The leading C<_> is a reminder that these subpragmas may not survive +beyond 5.8. More appropriate mechanisms for selecting the implementation +exist, but they wouldn't have arrived in time to save quicksort. + +=item * + +Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm +( http://burtleburtle.net/bob/hash/doobs.html ). This algorithm is +reasonably fast while producing a much better spread of values than +the old hashing algorithm (originally by Chris Torek, later tweaked by +Ilya Zakharevich). Hash values output from the algorithm on a hash of +all 3-char printable ASCII keys comes much closer to passing the +DIEHARD random number generation tests. According to perlbench, this +change has not affected the overall speed of Perl. + +=item * + +unshift() should now be noticeably faster. + +=back + +=head1 Installation and Configuration Improvements + +=head2 Generic Improvements + +=over 4 + +=item * + +INSTALL now explains how you can configure Perl to use 64-bit +integers even on non-64-bit platforms. + +=item * + +Policy.sh policy change: if you are reusing a Policy.sh file +(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old +Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of +them will now be changed to the new prefix, /foo/bar. (Previously +only $prefix changed.) If you do not like this new behaviour, +specify prefix, siteprefix, and vendorprefix explicitly. + +=item * + +A new optional location for Perl libraries, otherlibdirs, is available. +It can be used for example for vendor add-ons without disturbing Perl's +own library directories. + +=item * + +In many platforms, the vendor-supplied 'cc' is too stripped-down to +build Perl (basically, 'cc' doesn't do ANSI C). If this seems +to be the case and 'cc' does not seem to be the GNU C compiler +'gcc', an automatic attempt is made to find and use 'gcc' instead. + +=item * + +gcc needs to closely track the operating system release to avoid +build problems. If Configure finds that gcc was built for a different +operating system release than is running, it now gives a clearly visible +warning that there may be trouble ahead. + +=item * + +Since Perl 5.8 is not binary-compatible with previous releases +of Perl, Configure no longer suggests including the 5.005 +modules in @INC. + +=item * + +Configure C<-S> can now run non-interactively. [561] + +=item * + +Configure support for pdp11-style memory models has been removed due +to obsolescence. [561] + +=item * + +configure.gnu now works with options with whitespace in them. + +=item * + +installperl now outputs everything to STDERR. + +=item * + +Because PerlIO is now the default on most platforms, "-perlio" doesn't +get appended to the $Config{archname} (also known as $^O) anymore. +Instead, if you explicitly choose not to use perlio (Configure command +line option -Uuseperlio), you will get "-stdio" appended. + +=item * + +Another change related to the architecture name is that "-64all" +(-Duse64bitall, or "maximally 64-bit") is appended only if your +pointers are 64 bits wide. (To be exact, the use64bitall is ignored.) + +=item * + +In AFS installations, one can configure the root of the AFS to be +somewhere else than the default F</afs> by using the Configure +parameter C<-Dafsroot=/some/where/else>. + +=item * + +APPLLIB_EXP, a lesser-known configuration-time definition, has been +documented. It can be used to prepend site-specific directories +to Perl's default search path (@INC); see INSTALL for information. + +=item * + +The version of Berkeley DB used when the Perl (and, presumably, the +DB_File extension) was built is now available as +C<@Config{qw(db_version_major db_version_minor db_version_patch)}> +from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG +DB_VERSION_PATCH_CFG> from C. + +=item * + +Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM +has been documented in INSTALL. + +=item * + +If you have CPAN access (either network or a local copy such as a +CD-ROM) you can during specify extra modules to Configure to build and +install with Perl using the -Dextras=... option. See INSTALL for +more details. + +=item * + +In addition to config.over, a new override file, config.arch, is +available. This file is supposed to be used by hints file writers +for architecture-wide changes (as opposed to config.over which is +for site-wide changes). + +=item * + +If your file system supports symbolic links, you can build Perl outside +of the source directory by + + mkdir perl/build/directory + cd perl/build/directory + sh /path/to/perl/source/Configure -Dmksymlinks ... + +This will create in perl/build/directory a tree of symbolic links +pointing to files in /path/to/perl/source. The original files are left +unaffected. After Configure has finished, you can just say + + make all test + +and Perl will be built and tested, all in perl/build/directory. +[561] + +=item * + +For Perl developers, several new make targets for profiling +and debugging have been added; see L<perlhack>. + +=over 8 + +=item * + +Use of the F<gprof> tool to profile Perl has been documented in +L<perlhack>. There is a make target called "perl.gprof" for +generating a gprofiled Perl executable. + +=item * + +If you have GCC 3, there is a make target called "perl.gcov" for +creating a gcoved Perl executable for coverage analysis. See +L<perlhack>. + +=item * + +If you are on IRIX or Tru64 platforms, new profiling/debugging options +have been added; see L<perlhack> for more information about pixie and +Third Degree. + +=back + +=item * + +Guidelines of how to construct minimal Perl installations have +been added to INSTALL. + +=item * + +The Thread extension is now not built at all under ithreads +(C<Configure -Duseithreads>) because it wouldn't work anyway (the +Thread extension requires being Configured with C<-Duse5005threads>). + +B<Note that the 5.005 threads are unsupported and deprecated: if you +have code written for the old threads you should migrate it to the +new ithreads model.> + +=item * + +The Gconvert macro ($Config{d_Gconvert}) used by perl for stringifying +floating-point numbers is now more picky about using sprintf %.*g +rules for the conversion. Some platforms that used to use gcvt may +now resort to the slower sprintf. + +=item * + +The obsolete method of making a special (e.g., debugging) flavor +of perl by saying + + make LIBPERL=libperld.a + +has been removed. Use -DDEBUGGING instead. + +=back + +=head2 New Or Improved Platforms + +For the list of platforms known to support Perl, +see L<perlport/"Supported Platforms">. + +=over 4 + +=item * + +AIX dynamic loading should be now better supported. + +=item * + +AIX should now work better with gcc, threads, and 64-bitness. Also the +long doubles support in AIX should be better now. See L<perlaix>. + +=item * + +AtheOS ( http://www.atheos.cx/ ) is a new platform. + +=item * + +BeOS has been reclaimed. + +=item * + +The DG/UX platform now supports 5.005-style threads. +See L<perldgux>. + +=item * + +The DYNIX/ptx platform (also known as dynixptx) is supported at or +near osvers 4.5.2. + +=item * + +EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC, and VM/ESA) +have been regained. Many test suite tests still fail and the +co-existence of Unicode and EBCDIC isn't quite settled, but the +situation is much better than with Perl 5.6. See L<perlos390>, +L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information. + +=item * + +Building perl with -Duseithreads or -Duse5005threads now works under +HP-UX 10.20 (previously it only worked under 10.30 or later). You will +need a thread library package installed. See README.hpux. [561] + +=item * + +Mac OS Classic is now supported in the mainstream source package +(MacPerl has of course been available since perl 5.004 but now the +source code bases of standard Perl and MacPerl have been synchronised) +[561] + +=item * + +Mac OS X (or Darwin) should now be able to build Perl even on HFS+ +filesystems. (The case-insensitivity used to confuse the Perl build +process.) + +=item * + +NCR MP-RAS is now supported. [561] + +=item * + +All the NetBSD specific patches (except for the installation +specific ones) have been merged back to the main distribution. + +=item * + +NetWare from Novell is now supported. See L<perlnetware>. + +=item * + +NonStop-UX is now supported. [561] + +=item * + +NEC SUPER-UX is now supported. + +=item * + +All the OpenBSD specific patches (except for the installation +specific ones) have been merged back to the main distribution. + +=item * + +Perl has been tested with the GNU pth userlevel thread package +( http://www.gnu.org/software/pth/pth.html ). All thread tests +of Perl now work, but not without adding some yield()s to the tests, +so while pth (and other userlevel thread implementations) can be +considered to be "working" with Perl ithreads, keep in mind the +possible non-preemptability of the underlying thread implementation. + +=item * + +Stratus VOS is now supported using Perl's native build method +(Configure). This is the recommended method to build Perl on +VOS. The older methods, which build miniperl, are still +available. See L<perlvos>. [561+] + +=item * + +The Amdahl UTS UNIX mainframe platform is now supported. [561] + +=item * + +WinCE is now supported. See L<perlce>. + +=item * + +z/OS (formerly known as OS/390, formerly known as MVS OE) now has +support for dynamic loading. This is not selected by default, +however, you must specify -Dusedl in the arguments of Configure. [561] + +=back + +=head1 Selected Bug Fixes + +Numerous memory leaks and uninitialized memory accesses have been +hunted down. Most importantly, anonymous subs used to leak quite +a bit. [561] + +=over 4 + +=item * + +The autouse pragma didn't work for Multi::Part::Function::Names. + +=item * + +caller() could cause core dumps in certain situations. Carp was +sometimes affected by this problem. In particular, caller() now +returns a subroutine name of C<(unknown)> for subroutines that have +been removed from the symbol table. + +=item * + +chop(@list) in list context returned the characters chopped in +reverse order. This has been reversed to be in the right order. [561] + +=item * + +Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm) +when building the Perl binary. The only exception to this is SunOS 4.x, +which needs them. [561] + +=item * + +The behaviour of non-decimal but numeric string constants such as +"0x23" was platform-dependent: in some platforms that was seen as 35, +in some as 0, in some as a floating point number (don't ask). This +was caused by Perl's using the operating system libraries in a situation +where the result of the string to number conversion is undefined: now +Perl consistently handles such strings as zero in numeric contexts. + +=item * + +Several debugger fixes: exit code now reflects the script exit code, +condition C<"0"> now treated correctly, the C<d> command now checks +line number, C<$.> no longer gets corrupted, and all debugger output +now goes correctly to the socket if RemotePort is set. [561] + +=item * + +The debugger (perl5db.pl) has been modified to present a more +consistent commands interface, via (CommandSet=580). perl5db.t was +also added to test the changes, and as a placeholder for further tests. + +See L<perldebug>. + +=item * + +The debugger has a new C<dumpDepth> option to control the maximum +depth to which nested structures are dumped. The C<x> command has +been extended so that C<x N EXPR> dumps out the value of I<EXPR> to a +depth of at most I<N> levels. + +=item * + +The debugger can now show lexical variables if you have the CPAN +module PadWalker installed. + +=item * + +The order of DESTROYs has been made more predictable. + +=item * + +Perl 5.6.0 could emit spurious warnings about redefinition of +dl_error() when statically building extensions into perl. +This has been corrected. [561] + +=item * + +L<dprofpp> -R didn't work. + +=item * + +C<*foo{FORMAT}> now works. + +=item * + +Infinity is now recognized as a number. + +=item * + +UNIVERSAL::isa no longer caches methods incorrectly. (This broke +the Tk extension with 5.6.0.) [561] + +=item * + +Lexicals I: lexicals outside an eval "" weren't resolved +correctly inside a subroutine definition inside the eval "" if they +were not already referenced in the top level of the eval""ed code. + +=item * + +Lexicals II: lexicals leaked at file scope into subroutines that +were declared before the lexicals. + +=item * + +Lexical warnings now propagating correctly between scopes +and into C<eval "...">. + +=item * + +C<use warnings qw(FATAL all)> did not work as intended. This has been +corrected. [561] + +=item * + +warnings::enabled() now reports the state of $^W correctly if the caller +isn't using lexical warnings. [561] + +=item * + +Line renumbering with eval and C<#line> now works. [561] + +=item * + +Fixed numerous memory leaks, especially in eval "". + +=item * + +Localised tied variables no longer leak memory + + use Tie::Hash; + tie my %tied_hash => 'Tie::StdHash'; + + ... + + # Used to leak memory every time local() was called; + # in a loop, this added up. + local($tied_hash{Foo}) = 1; + +=item * + +Localised hash elements (and %ENV) are correctly unlocalised to not +exist, if they didn't before they were localised. + + + use Tie::Hash; + tie my %tied_hash => 'Tie::StdHash'; + + ... + + # Nothing has set the FOO element so far + + { local $tied_hash{FOO} = 'Bar' } + + # This used to print, but not now. + print "exists!\n" if exists $tied_hash{FOO}; + +As a side effect of this fix, tied hash interfaces B<must> define +the EXISTS and DELETE methods. + +=item * + +mkdir() now ignores trailing slashes in the directory name, +as mandated by POSIX. + +=item * + +Some versions of glibc have a broken modfl(). This affects builds +with C<-Duselongdouble>. This version of Perl detects this brokenness +and has a workaround for it. The glibc release 2.2.2 is known to have +fixed the modfl() bug. + +=item * + +Modulus of unsigned numbers now works (4063328477 % 65535 used to +return 27406, instead of 27047). [561] + +=item * + +Some "not a number" warnings introduced in 5.6.0 eliminated to be +more compatible with 5.005. Infinity is now recognised as a number. [561] + +=item * + +Numeric conversions did not recognize changes in the string value +properly in certain circumstances. [561] + +=item * + +Attributes (such as :shared) didn't work with our(). + +=item * + +our() variables will not cause bogus "Variable will not stay shared" +warnings. [561] + +=item * + +"our" variables of the same name declared in two sibling blocks +resulted in bogus warnings about "redeclaration" of the variables. +The problem has been corrected. [561] + +=item * + +pack "Z" now correctly terminates the string with "\0". + +=item * + +Fix password routines which in some shadow password platforms +(e.g. HP-UX) caused getpwent() to return every other entry. + +=item * + +The PERL5OPT environment variable (for passing command line arguments +to Perl) didn't work for more than a single group of options. [561] + +=item * + +PERL5OPT with embedded spaces didn't work. + +=item * + +printf() no longer resets the numeric locale to "C". + +=item * + +C<qw(a\\b)> now parses correctly as C<'a\\b'>: that is, as three +characters, not four. [561] + +=item * + +pos() did not return the correct value within s///ge in earlier +versions. This is now handled correctly. [561] + +=item * + +Printing quads (64-bit integers) with printf/sprintf now works +without the q L ll prefixes (assuming you are on a quad-capable platform). + +=item * + +Regular expressions on references and overloaded scalars now work. [561+] + +=item * + +Right-hand side magic (GMAGIC) could in many cases such as string +concatenation be invoked too many times. + +=item * + +scalar() now forces scalar context even when used in void context. + +=item * + +SOCKS support is now much more robust. + +=item * + +sort() arguments are now compiled in the right wantarray context +(they were accidentally using the context of the sort() itself). +The comparison block is now run in scalar context, and the arguments +to be sorted are always provided list context. [561] + +=item * + +Changed the POSIX character class C<[[:space:]]> to include the (very +rarely used) vertical tab character. Added a new POSIX-ish character +class C<[[:blank:]]> which stands for horizontal whitespace +(currently, the space and the tab). + +=item * + +The tainting behaviour of sprintf() has been rationalized. It does +not taint the result of floating point formats anymore, making the +behaviour consistent with that of string interpolation. [561] + +=item * + +Some cases of inconsistent taint propagation (such as within hash +values) have been fixed. + +=item * + +The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds +of simple pattern matches. These are now handled better. [561] + +=item * + +Regular expression debug output (whether through C<use re 'debug'> +or via C<-Dr>) now looks better. [561] + +=item * + +Multi-line matches like C<"a\nxb\n" =~ /(?!\A)x/m> were flawed. The +bug has been fixed. [561] + +=item * + +Use of $& could trigger a core dump under some situations. This +is now avoided. [561] + +=item * + +The regular expression captured submatches ($1, $2, ...) are now +more consistently unset if the match fails, instead of leaving false +data lying around in them. [561] + +=item * + +readline() on files opened in "slurp" mode could return an extra +"" (blank line) at the end in certain situations. This has been +corrected. [561] + +=item * + +Autovivification of symbolic references of special variables described +in L<perlvar> (as in C<${$num}>) was accidentally disabled. This works +again now. [561] + +=item * + +Sys::Syslog ignored the C<LOG_AUTH> constant. + +=item * + +$AUTOLOAD, sort(), lock(), and spawning subprocesses +in multiple threads simultaneously are now thread-safe. + +=item * + +Tie::Array's SPLICE method was broken. + +=item * + +Allow a read-only string on the left-hand side of a non-modifying tr///. + +=item * + +If C<STDERR> is tied, warnings caused by C<warn> and C<die> now +correctly pass to it. + +=item * + +Several Unicode fixes. + +=over 8 + +=item * + +BOMs (byte order marks) at the beginning of Perl files +(scripts, modules) should now be transparently skipped. +UTF-16 and UCS-2 encoded Perl files should now be read correctly. + +=item * + +The character tables have been updated to Unicode 3.2.0. + +=item * + +Comparing with utf8 data does not magically upgrade non-utf8 data +into utf8. (This was a problem for example if you were mixing data +from I/O and Unicode data: your output might have got magically encoded +as UTF-8.) + +=item * + +Generating illegal Unicode code points such as U+FFFE, or the UTF-16 +surrogates, now also generates an optional warning. + +=item * + +C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase. + +=item * + +Concatenation with the C<.> operator or via variable interpolation, +C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator, +substitution with C<s///>, single-quoted UTF-8, should now work. + +=item * + +The C<tr///> operator now works. Note that the C<tr///CU> +functionality has been removed (but see pack('U0', ...)). + +=item * + +C<eval "v200"> now works. + +=item * + +Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings. +This has been corrected. [561] + +=item * + +Zero entries were missing from the Unicode classes such as C<IsDigit>. + +=back + +=item * + +Large unsigned numbers (those above 2**31) could sometimes lose their +unsignedness, causing bogus results in arithmetic operations. [561] + +=item * + +The Perl parser has been stress tested using both random input and +Markov chain input and the few found crashes and lockups have been +fixed. + +=back + +=head2 Platform Specific Changes and Fixes + +=over 4 + +=item * + +BSDI 4.* + +Perl now works on post-4.0 BSD/OSes. + +=item * + +All BSDs + +Setting C<$0> now works (as much as possible; see L<perlvar> for details). + +=item * + +Cygwin + +Numerous updates; currently synchronised with Cygwin 1.3.10. + +=item * + +Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O. + +=item * + +EPOC + +EPOC now better supported. See README.epoc. [561] + +=item * + +FreeBSD 3.* + +Perl now works on post-3.0 FreeBSDs. + +=item * + +HP-UX + +README.hpux updated; C<Configure -Duse64bitall> now works; +now uses HP-UX malloc instead of Perl malloc. + +=item * + +IRIX + +Numerous compilation flag and hint enhancements; accidental mixing +of 32-bit and 64-bit libraries (a doomed attempt) made much harder. + +=item * + +Linux + +=over 8 + +=item * + +Long doubles should now work (see INSTALL). [561] + +=item * + +Linux previously had problems related to sockaddrlen when using +accept(), recvfrom() (in Perl: recv()), getpeername(), and +getsockname(). + +=back + +=item * + +Mac OS Classic + +Compilation of the standard Perl distribution in Mac OS Classic should +now work if you have the Metrowerks development environment and the +missing Mac-specific toolkit bits. Contact the macperl mailing list +for details. + +=item * + +MPE/iX + +MPE/iX update after Perl 5.6.0. See README.mpeix. [561] + +=item * + +NetBSD/threads: try installing the GNU pth (should be in the +packages collection, or http://www.gnu.org/software/pth/), +and Configure with -Duseithreads. + +=item * + +NetBSD/sparc + +Perl now works on NetBSD/sparc. + +=item * + +OS/2 + +Now works with usethreads (see INSTALL). [561] + +=item * + +Solaris + +64-bitness using the Sun Workshop compiler now works. + +=item * + +Stratus VOS + +The native build method requires at least VOS Release 14.5.0 +and GNU C++/GNU Tools 2.0.1 or later. The Perl pack function +now maps overflowed values to +infinity and underflowed values +to -infinity. + +=item * + +Tru64 (aka Digital UNIX, aka DEC OSF/1) + +The operating system version letter now recorded in $Config{osvers}. +Allow compiling with gcc (previously explicitly forbidden). Compiling +with gcc still not recommended because buggy code results, even with +gcc 2.95.2. + +=item * + +Unicos + +Fixed various alignment problems that lead into core dumps either +during build or later; no longer dies on math errors at runtime; +now using full quad integers (64 bits), previously was using +only 46 bit integers for speed. + +=item * + +VMS + +See L</"Socket Extension Dynamic in VMS"> and L</"IEEE-format Floating Point +Default on OpenVMS Alpha"> for important changes not otherwise listed here. + +chdir() now works better despite a CRT bug; now works with MULTIPLICITY +(see INSTALL); now works with Perl's malloc. + +The tainting of C<%ENV> elements via C<keys> or C<values> was previously +unimplemented. It now works as documented. + +The C<waitpid> emulation has been improved. The worst bug (now fixed) +was that a pid of -1 would cause a wildcard search of all processes on +the system. + +POSIX-style signals are now emulated much better on VMS versions prior +to 7.0. + +The C<system> function and backticks operator have improved +functionality and better error handling. [561] + +File access tests now use current process privileges rather than the +user's default privileges, which could sometimes result in a mismatch +between reported access and actual access. This improvement is only +available on VMS v6.0 and later. + +There is a new C<kill> implementation based on C<sys$sigprc> that allows +older VMS systems (pre-7.0) to use C<kill> to send signals rather than +simply force exit. This implementation also allows later systems to +call C<kill> from within a signal handler. + +Iterative logical name translations are now limited to 10 iterations in +imitation of SHOW LOGICAL and other OpenVMS facilities. + +=item * + +Windows + +=over 8 + +=item * + +Signal handling now works better than it used to. It is now implemented +using a Windows message loop, and is therefore less prone to random +crashes. + +=item * + +fork() emulation is now more robust, but still continues to have a few +esoteric bugs and caveats. See L<perlfork> for details. [561+] + +=item * + +A failed (pseudo)fork now returns undef and sets errno to EAGAIN. [561] + +=item * + +The following modules now work on Windows: + + ExtUtils::Embed [561] + IO::Pipe + IO::Poll + Net::Ping + +=item * + +IO::File::new_tmpfile() is no longer limited to 32767 invocations +per-process. + +=item * + +Better chdir() return value for a non-existent directory. + +=item * + +Compiling perl using the 64-bit Platform SDK tools is now supported. + +=item * + +The Win32::SetChildShowWindow() builtin can be used to control the +visibility of windows created by child processes. See L<Win32> for +details. + +=item * + +Non-blocking waits for child processes (or pseudo-processes) are +supported via C<waitpid($pid, &POSIX::WNOHANG)>. + +=item * + +The behavior of system() with multiple arguments has been rationalized. +Each unquoted argument will be automatically quoted to protect whitespace, +and any existing whitespace in the arguments will be preserved. This +improves the portability of system(@args) by avoiding the need for +Windows C<cmd> shell specific quoting in perl programs. + +Note that this means that some scripts that may have relied on earlier +buggy behavior may no longer work correctly. For example, +C<system("nmake /nologo", @args)> will now attempt to run the file +C<nmake /nologo> and will fail when such a file isn't found. +On the other hand, perl will now execute code such as +C<system("c:/Program Files/MyApp/foo.exe", @args)> correctly. + +=item * + +The perl header files no longer suppress common warnings from the +Microsoft Visual C++ compiler. This means that additional warnings may +now show up when compiling XS code. + +=item * + +Borland C++ v5.5 is now a supported compiler that can build Perl. +However, the generated binaries continue to be incompatible with those +generated by the other supported compilers (GCC and Visual C++). [561] + +=item * + +Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x. +[561] + +=item * + +Current directory entries in %ENV are now correctly propagated to child +processes. [561] + +=item * + +New %ENV entries now propagate to subprocesses. [561] + +=item * + +Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root. +Other bugs in chdir() and Cwd::cwd() have also been fixed. [561] + +=item * + +The makefiles now default to the features enabled in ActiveState ActivePerl +(a popular Win32 binary distribution). [561] + +=item * + +HTML files will now be installed in c:\perl\html instead of +c:\perl\lib\pod\html + +=item * + +REG_EXPAND_SZ keys are now allowed in registry settings used by perl. [561] + +=item * + +Can now send() from all threads, not just the first one. [561] + +=item * + +ExtUtils::MakeMaker now uses $ENV{LIB} to search for libraries. [561] + +=item * + +Less stack reserved per thread so that more threads can run +concurrently. (Still 16M per thread.) [561] + +=item * + +C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp +(works better when perl is running as service). + +=item * + +Better UNC path handling under ithreads. [561] + +=item * + +wait(), waitpid(), and backticks now return the correct exit status +under Windows 9x. [561] + +=item * + +A socket handle leak in accept() has been fixed. [561] + +=back + +=back + +=head1 New or Changed Diagnostics + +Please see L<perldiag> for more details. + +=over 4 + +=item * + +Ambiguous range in the transliteration operator (like a-z-9) now +gives a warning. + +=item * + +chdir("") and chdir(undef) now give a deprecation warning because they +cause a possible unintentional chdir to the home directory. +Say chdir() if you really mean that. + +=item * + +Two new debugging options have been added: if you have compiled your +Perl with debugging, you can use the -DT [561] and -DR options to trace +tokenising and to add reference counts to displaying variables, +respectively. + +=item * + +The lexical warnings category "deprecated" is no longer a sub-category +of the "syntax" category. It is now a top-level category in its own +right. + +=item * + +Unadorned dump() will now give a warning suggesting to +use explicit CORE::dump() if that's what really is meant. + +=item * + +The "Unrecognized escape" warning has been extended to include C<\8>, +C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters. + +=item * + +All regular expression compilation error messages are now hopefully +easier to understand both because the error message now comes before +the failed regex and because the point of failure is now clearly +marked by a C<E<lt>-- HERE> marker. + +=item * + +Various I/O (and socket) functions like binmode(), close(), and so +forth now more consistently warn if they are used illogically either +on a yet unopened or on an already closed filehandle (or socket). + +=item * + +Using lstat() on a filehandle now gives a warning. (It's a non-sensical +thing to do.) + +=item * + +The C<-M> and C<-m> options now warn if you didn't supply the module name. + +=item * + +If you in C<use> specify a required minimum version, modules matching +the name and but not defining a $VERSION will cause a fatal failure. + +=item * + +Using negative offset for vec() in lvalue context is now a warnable offense. + +=item * + +Odd number of arguments to overload::constant now elicits a warning. + +=item * + +Odd number of elements in anonymous hash now elicits a warning. + +=item * + +The various "opened only for", "on closed", "never opened" warnings +drop the C<main::> prefix for filehandles in the C<main> package, +for example C<STDIN> instead of C<main::STDIN>. + +=item * + +Subroutine prototypes are now checked more carefully, you may +get warnings for example if you have used non-prototype characters. + +=item * + +If an attempt to use a (non-blessed) reference as an array index +is made, a warning is given. + +=item * + +C<push @a;> and C<unshift @a;> (with no values to push or unshift) +now give a warning. This may be a problem for generated and eval'ed +code. + +=item * + +If you try to L<perlfunc/pack> a number less than 0 or larger than 255 +using the C<"C"> format you will get an optional warning. Similarly +for the C<"c"> format and a number less than -128 or more than 127. + +=item * + +pack C<P> format now demands an explicit size. + +=item * + +unpack C<w> now warns of unterminated compressed integers. + +=item * + +Warnings relating to the use of PerlIO have been added. + +=item * + +Certain regex modifiers such as C<(?o)> make sense only if applied to +the entire regex. You will get an optional warning if you try to do +otherwise. + +=item * + +Variable length lookbehind has not yet been implemented, trying to +use it will tell that. + +=item * + +Using arrays or hashes as references (e.g. C<< %foo->{bar} >> +has been deprecated for a while. Now you will get an optional warning. + +=item * + +Warnings relating to the use of the new restricted hashes feature +have been added. + +=item * + +Self-ties of arrays and hashes are not supported and fatal errors +will happen even at an attempt to do so. + +=item * + +Using C<sort> in scalar context now issues an optional warning. +This didn't do anything useful, as the sort was not performed. + +=item * + +Using the /g modifier in split() is meaningless and will cause a warning. + +=item * + +Using splice() past the end of an array now causes a warning. + +=item * + +Malformed Unicode encodings (UTF-8 and UTF-16) cause a lot of warnings, +as does trying to use UTF-16 surrogates (which are unimplemented). + +=item * + +Trying to use Unicode characters on an I/O stream without marking the +stream's encoding (using open() or binmode()) will cause "Wide character" +warnings. + +=item * + +Use of v-strings in use/require causes a (backward) portability warning. + +=item * + +Warnings relating to the use interpreter threads and their shared data +have been added. + +=back + +=head1 Changed Internals + +=over 4 + +=item * + +PerlIO is now the default. + +=item * + +perlapi.pod (a companion to perlguts) now attempts to document the +internal API. + +=item * + +You can now build a really minimal perl called microperl. +Building microperl does not require even running Configure; +C<make -f Makefile.micro> should be enough. Beware: microperl makes +many assumptions, some of which may be too bold; the resulting +executable may crash or otherwise misbehave in wondrous ways. +For careful hackers only. + +=item * + +Added rsignal(), whichsig(), do_join(), op_clear, op_null, +ptr_table_clear(), ptr_table_free(), sv_setref_uv(), and several UTF-8 +interfaces to the publicised API. For the full list of the available +APIs see L<perlapi>. + +=item * + +Made possible to propagate customised exceptions via croak()ing. + +=item * + +Now xsubs can have attributes just like subs. (Well, at least the +built-in attributes.) + +=item * + +dTHR and djSP have been obsoleted; the former removed (because it's +a no-op) and the latter replaced with dSP. + +=item * + +PERL_OBJECT has been completely removed. + +=item * + +The MAGIC constants (e.g. C<'P'>) have been macrofied +(e.g. C<PERL_MAGIC_TIED>) for better source code readability +and maintainability. + +=item * + +The regex compiler now maintains a structure that identifies nodes in +the compiled bytecode with the corresponding syntactic features of the +original regex expression. The information is attached to the new +C<offsets> member of the C<struct regexp>. See L<perldebguts> for more +complete information. + +=item * + +The C code has been made much more C<gcc -Wall> clean. Some warning +messages still remain in some platforms, so if you are compiling with +gcc you may see some warnings about dubious practices. The warnings +are being worked on. + +=item * + +F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented. + +=item * + +Documentation on how to use the Perl source repository has been added +to F<Porting/repository.pod>. + +=item * + +There are now several profiling make targets. + +=back + +=head1 Security Vulnerability Closed [561] + +(This change was already made in 5.7.0 but bears repeating here.) +(5.7.0 came out before 5.6.1: the development branch 5.7 released +earlier than the maintenance branch 5.6) + +A potential security vulnerability in the optional suidperl component +of Perl was identified in August 2000. suidperl is neither built nor +installed by default. As of November 2001 the only known vulnerable +platform is Linux, most likely all Linux distributions. CERT and +various vendors and distributors have been alerted about the vulnerability. +See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt +for more information. + +The problem was caused by Perl trying to report a suspected security +exploit attempt using an external program, /bin/mail. On Linux +platforms the /bin/mail program had an undocumented feature which +when combined with suidperl gave access to a root shell, resulting in +a serious compromise instead of reporting the exploit attempt. If you +don't have /bin/mail, or if you have 'safe setuid scripts', or if +suidperl is not installed, you are safe. + +The exploit attempt reporting feature has been completely removed from +Perl 5.8.0 (and the maintenance release 5.6.1, and it was removed also +from all the Perl 5.7 releases), so that particular vulnerability +isn't there anymore. However, further security vulnerabilities are, +unfortunately, always possible. The suidperl functionality is most +probably going to be removed in Perl 5.10. In any case, suidperl +should only be used by security experts who know exactly what they are +doing and why they are using suidperl instead of some other solution +such as sudo ( see http://www.courtesan.com/sudo/ ). + +=head1 New Tests + +Several new tests have been added, especially for the F<lib> and +F<ext> subsections. There are now about 69 000 individual tests +(spread over about 700 test scripts), in the regression suite (5.6.1 +has about 11 700 tests, in 258 test scripts) The exact numbers depend +on the platform and Perl configuration used. Many of the new tests +are of course introduced by the new modules, but still in general Perl +is now more thoroughly tested. + +Because of the large number of tests, running the regression suite +will take considerably longer time than it used to: expect the suite +to take up to 4-5 times longer to run than in perl 5.6. On a really +fast machine you can hope to finish the suite in about 6-8 minutes +(wallclock time). + +The tests are now reported in a different order than in earlier Perls. +(This happens because the test scripts from under t/lib have been moved +to be closer to the library/extension they are testing.) + +=head1 Known Problems + +=head2 The Compiler Suite Is Still Very Experimental + +The compiler suite is slowly getting better but it continues to be +highly experimental. Use in production environments is discouraged. + +=head2 Localising Tied Arrays and Hashes Is Broken + + local %tied_array; + +doesn't work as one would expect: the old value is restored +incorrectly. This will be changed in a future release, but we don't +know yet what the new semantics will exactly be. In any case, the +change will break existing code that relies on the current +(ill-defined) semantics, so just avoid doing this in general. + +=head2 Building Extensions Can Fail Because Of Largefiles + +Some extensions like mod_perl are known to have issues with +`largefiles', a change brought by Perl 5.6.0 in which file offsets +default to 64 bits wide, where supported. Modules may fail to compile +at all, or they may compile and work incorrectly. Currently, there +is no good solution for the problem, but Configure now provides +appropriate non-largefile ccflags, ldflags, libswanted, and libs +in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the +extensions that are having problems can try configuring themselves +without the largefileness. This is admittedly not a clean solution, +and the solution may not even work at all. One potential failure is +whether one can (or, if one can, whether it's a good idea to) link +together at all binaries with different ideas about file offsets; +all this is platform-dependent. + +=head2 Modifying $_ Inside for(..) + + for (1..5) { $_++ } + +works without complaint. It shouldn't. (You should be able to +modify only lvalue elements inside the loops.) You can see the +correct behaviour by replacing the 1..5 with 1, 2, 3, 4, 5. + +=head2 mod_perl 1.26 Doesn't Build With Threaded Perl + +Use mod_perl 1.27 or higher. + +=head2 lib/ftmp-security tests warn 'system possibly insecure' + +Don't panic. Read the 'make test' section of INSTALL instead. + +=head2 libwww-perl (LWP) fails base/date #51 + +Use libwww-perl 5.65 or later. + +=head2 PDL failing some tests + +Use PDL 2.3.4 or later. + +=head2 Perl_get_sv + +You may get errors like 'Undefined symbol "Perl_get_sv"' or "can't +resolve symbol 'Perl_get_sv'", or the symbol may be "Perl_sv_2pv". +This probably means that you are trying to use an older shared Perl +library (or extensions linked with such) with Perl 5.8.0 executable. +Perl used to have such a subroutine, but that is no more the case. +Check your shared library path, and any shared Perl libraries in those +directories. + +Sometimes this problem may also indicate a partial Perl 5.8.0 +installation, see L</"Mac OS X dyld undefined symbols"> for an +example and how to deal with it. + +=head2 Self-tying Problems + +Self-tying of arrays and hashes is broken in rather deep and +hard-to-fix ways. As a stop-gap measure to avoid people from getting +frustrated at the mysterious results (core dumps, most often), it is +forbidden for now (you will get a fatal error even from an attempt). + +A change to self-tying of globs has caused them to be recursively +referenced (see: L<perlobj/"Two-Phased Garbage Collection">). You +will now need an explicit untie to destroy a self-tied glob. This +behaviour may be fixed at a later date. + +Self-tying of scalars and IO thingies works. + +=head2 ext/threads/t/libc + +If this test fails, it indicates that your libc (C library) is not +threadsafe. This particular test stress tests the localtime() call to +find out whether it is threadsafe. See L<perlthrtut> for more information. + +=head2 Failure of Thread (5.005-style) tests + +B<Note that support for 5.005-style threading is deprecated, +experimental and practically unsupported. In 5.10, it is expected +to be removed. You should migrate your code to ithreads.> + +The following tests are known to fail due to fundamental problems in +the 5.005 threading implementation. These are not new failures--Perl +5.005_0x has the same bugs, but didn't have these tests. + + ../ext/B/t/xref.t 255 65280 14 12 85.71% 3-14 + ../ext/List/Util/t/first.t 255 65280 7 4 57.14% 2 5-7 + ../lib/English.t 2 512 54 2 3.70% 2-3 + ../lib/FileCache.t 5 1 20.00% 5 + ../lib/Filter/Simple/t/data.t 6 3 50.00% 1-3 + ../lib/Filter/Simple/t/filter_only. 9 3 33.33% 1-2 5 + ../lib/Math/BigInt/t/bare_mbf.t 1627 4 0.25% 8 11 1626-1627 + ../lib/Math/BigInt/t/bigfltpm.t 1629 4 0.25% 10 13 1628- + 1629 + ../lib/Math/BigInt/t/sub_mbf.t 1633 4 0.24% 8 11 1632-1633 + ../lib/Math/BigInt/t/with_sub.t 1628 4 0.25% 9 12 1627-1628 + ../lib/Tie/File/t/31_autodefer.t 255 65280 65 32 49.23% 34-65 + ../lib/autouse.t 10 1 10.00% 4 + op/flip.t 15 1 6.67% 15 + +These failures are unlikely to get fixed as 5.005-style threads +are considered fundamentally broken. (Basically what happens is that +competing threads can corrupt shared global state, one good example +being regular expression engine's state.) + +=head2 Timing problems + +The following tests may fail intermittently because of timing +problems, for example if the system is heavily loaded. + + t/op/alarm.t + ext/Time/HiRes/HiRes.t + lib/Benchmark.t + lib/Memoize/t/expmod_t.t + lib/Memoize/t/speed.t + +In case of failure please try running them manually, for example + + ./perl -Ilib ext/Time/HiRes/HiRes.t + +=head2 Tied/Magical Array/Hash Elements Do Not Autovivify + +For normal arrays C<$foo = \$bar[1]> will assign C<undef> to +C<$bar[1]> (assuming that it didn't exist before), but for +tied/magical arrays and hashes such autovivification does not happen +because there is currently no way to catch the reference creation. +The same problem affects slicing over non-existent indices/keys of +a tied/magical array/hash. + +=head2 Unicode in package/class and subroutine names does not work + +One can have Unicode in identifier names, but not in package/class or +subroutine names. While some limited functionality towards this does +exist as of Perl 5.8.0, that is more accidental than designed; use of +Unicode for the said purposes is unsupported. + +One reason of this unfinishedness is its (currently) inherent +unportability: since both package names and subroutine names may +need to be mapped to file and directory names, the Unicode capability +of the filesystem becomes important-- and there unfortunately aren't +portable answers. + +=head1 Platform Specific Problems + +=head2 AIX + +=over 4 + +=item * + +If using the AIX native make command, instead of just "make" issue +"make all". In some setups the former has been known to spuriously +also try to run "make install". Alternatively, you may want to use +GNU make. + +=item * + +In AIX 4.2, Perl extensions that use C++ functions that use statics +may have problems in that the statics are not getting initialized. +In newer AIX releases, this has been solved by linking Perl with +the libC_r library, but unfortunately in AIX 4.2 the said library +has an obscure bug where the various functions related to time +(such as time() and gettimeofday()) return broken values, and +therefore in AIX 4.2 Perl is not linked against libC_r. + +=item * + +vac 5.0.0.0 May Produce Buggy Code For Perl + +The AIX C compiler vac version 5.0.0.0 may produce buggy code, +resulting in a few random tests failing when run as part of "make +test", but when the failing tests are run by hand, they succeed. +We suggest upgrading to at least vac version 5.0.1.0, that has been +known to compile Perl correctly. "lslpp -L|grep vac.C" will tell +you the vac version. See README.aix. + +=item * + +If building threaded Perl, you may get compilation warning from pp_sys.c: + + "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed. + +This is harmless; it is caused by the getnetbyaddr() and getnetbyaddr_r() +having slightly different types for their first argument. + +=back + +=head2 Alpha systems with old gccs fail several tests + +If you see op/pack, op/pat, op/regexp, or ext/Storable tests failing +in a Linux/alpha or *BSD/Alpha, it's probably time to upgrade your gcc. +gccs prior to 2.95.3 are definitely not good enough, and gcc 3.1 may +be even better. (RedHat Linux/alpha with gcc 3.1 reported no problems, +as did Linux 2.4.18 with gcc 2.95.4.) (In Tru64, it is preferable to +use the bundled C compiler.) + +=head2 AmigaOS + +Perl 5.8.0 doesn't build in AmigaOS. It broke at some point during +the ithreads work and we could not find Amiga experts to unbreak the +problems. Perl 5.6.1 still works for AmigaOS (as does the 5.7.2 +development release). + +=head2 BeOS + +The following tests fail on 5.8.0 Perl in BeOS Personal 5.03: + + t/op/lfs............................FAILED at test 17 + t/op/magic..........................FAILED at test 24 + ext/Fcntl/t/syslfs..................FAILED at test 17 + ext/File/Glob/t/basic...............FAILED at test 3 + ext/POSIX/t/sigaction...............FAILED at test 13 + ext/POSIX/t/waitpid.................FAILED at test 1 + +See L<perlbeos> (README.beos) for more details. + +=head2 Cygwin "unable to remap" + +For example when building the Tk extension for Cygwin, +you may get an error message saying "unable to remap". +This is known problem with Cygwin, and a workaround is +detailed in here: http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html + +=head2 Cygwin ndbm tests fail on FAT + +One can build but not install (or test the build of) the NDBM_File +on FAT filesystems. Installation (or build) on NTFS works fine. +If one attempts the test on a FAT install (or build) the following +failures are expected: + + ../ext/NDBM_File/ndbm.t 13 3328 71 59 83.10% 1-2 4 16-71 + ../ext/ODBM_File/odbm.t 255 65280 ?? ?? % ?? + ../lib/AnyDBM_File.t 2 512 12 2 16.67% 1 4 + ../lib/Memoize/t/errors.t 0 139 11 5 45.45% 7-11 + ../lib/Memoize/t/tie_ndbm.t 13 3328 4 4 100.00% 1-4 + run/fresh_perl.t 97 1 1.03% 91 + +NDBM_File fails and ODBM_File just coredumps. + +If you intend to run only on FAT (or if using AnyDBM_File on FAT), +run Configure with the -Ui_ndbm and -Ui_dbm options to prevent +NDBM_File and ODBM_File being built. + +=head2 DJGPP Failures + + t/op/stat............................FAILED at test 29 + lib/File/Find/t/find.................FAILED at test 1 + lib/File/Find/t/taint................FAILED at test 1 + lib/h2xs.............................FAILED at test 15 + lib/Pod/t/eol........................FAILED at test 1 + lib/Test/Harness/t/strap-analyze.....FAILED at test 8 + lib/Test/Harness/t/test-harness......FAILED at test 23 + lib/Test/Simple/t/exit...............FAILED at test 1 + +The above failures are known as of 5.8.0 with native builds with long +filenames, but there are a few more if running under dosemu because of +limitations (and maybe bugs) of dosemu: + + t/comp/cpp...........................FAILED at test 3 + t/op/inccode.........................(crash) + +and a few lib/ExtUtils tests, and several hundred Encode/t/Aliases.t +failures that work fine with long filenames. So you really might +prefer native builds and long filenames. + +=head2 FreeBSD built with ithreads coredumps reading large directories + +This is a known bug in FreeBSD 4.5's readdir_r(), it has been fixed in +FreeBSD 4.6 (see L<perlfreebsd> (README.freebsd)). + +=head2 FreeBSD Failing locale Test 117 For ISO 8859-15 Locales + +The ISO 8859-15 locales may fail the locale test 117 in FreeBSD. +This is caused by the characters \xFF (y with diaeresis) and \xBE +(Y with diaeresis) not behaving correctly when being matched +case-insensitively. Apparently this problem has been fixed in +the latest FreeBSD releases. +( http://www.freebsd.org/cgi/query-pr.cgi?pr=34308 ) + +=head2 IRIX fails ext/List/Util/t/shuffle.t or Digest::MD5 + +IRIX with MIPSpro 7.3.1.2m or 7.3.1.3m compiler may fail the List::Util +test ext/List/Util/t/shuffle.t by dumping core. This seems to be +a compiler error since if compiled with gcc no core dump ensues, and +no failures have been seen on the said test on any other platform. + +Similarly, building the Digest::MD5 extension has been +known to fail with "*** Termination code 139 (bu21)". + +The cure is to drop optimization level (Configure -Doptimize=-O2). + +=head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured + +If perl is configured with -Duse64bitall, the successful result of the +subtest 10 of lib/posix may arrive before the successful result of the +subtest 9, which confuses the test harness so much that it thinks the +subtest 9 failed. + +=head2 Linux with glibc 2.2.5 fails t/op/int subtest #6 with -Duse64bitint + +This is a known bug in the glibc 2.2.5 with long long integers. +( http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 ) + +=head2 Linux With Sfio Fails op/misc Test 48 + +No known fix. + +=head2 Mac OS X + +Please remember to set your environment variable LC_ALL to "C" +(setenv LC_ALL C) before running "make test" to avoid a lot of +warnings about the broken locales of Mac OS X. + +The following tests are known to fail in Mac OS X 10.1.5 because of +buggy (old) implementations of Berkeley DB included in Mac OS X: + + Failed Test Stat Wstat Total Fail Failed List of Failed + ------------------------------------------------------------------------- + ../ext/DB_File/t/db-btree.t 0 11 ?? ?? % ?? + ../ext/DB_File/t/db-recno.t 149 3 2.01% 61 63 65 + +If you are building on a UFS partition, you will also probably see +t/op/stat.t subtest #9 fail. This is caused by Darwin's UFS not +supporting inode change time. + +Also the ext/POSIX/t/posix.t subtest #10 fails but it is skipped for +now because the failure is Apple's fault, not Perl's (blocked signals +are lost). + +If you Configure with ithreads, ext/threads/t/libc.t will fail. Again, +this is not Perl's fault-- the libc of Mac OS X is not threadsafe +(in this particular test, the localtime() call is found to be +threadunsafe.) + +=head2 Mac OS X dyld undefined symbols + +If after installing Perl 5.8.0 you are getting warnings about missing +symbols, for example + + dyld: perl Undefined symbols + _perl_sv_2pv + _perl_get_sv + +you probably have an old pre-Perl-5.8.0 installation (or parts of one) +in /Library/Perl (the undefined symbols used to exist in pre-5.8.0 Perls). +It seems that for some reason "make install" doesn't always completely +overwrite the files in /Library/Perl. You can move the old Perl +shared library out of the way like this: + + cd /Library/Perl/darwin/CORE + mv libperl.dylib libperlold.dylib + +and then reissue "make install". Note that the above of course is +extremely disruptive for anything using the /usr/local/bin/perl. +If that doesn't help, you may have to try removing all the .bundle +files from beneath /Library/Perl, and again "make install"-ing. + +=head2 OS/2 Test Failures + +The following tests are known to fail on OS/2 (for clarity +only the failures are shown, not the full error messages): + + ../lib/ExtUtils/t/Mkbootstrap.t 1 256 18 1 5.56% 8 + ../lib/ExtUtils/t/Packlist.t 1 256 34 1 2.94% 17 + ../lib/ExtUtils/t/basic.t 1 256 17 1 5.88% 14 + lib/os2_process.t 2 512 227 2 0.88% 174 209 + lib/os2_process_kid.t 227 2 0.88% 174 209 + lib/rx_cmprt.t 255 65280 18 3 16.67% 16-18 + +=head2 op/sprintf tests 91, 129, and 130 + +The op/sprintf tests 91, 129, and 130 are known to fail on some platforms. +Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX. + +Test 91 is known to fail on QNX6 (nto), because C<sprintf '%e',0> +incorrectly produces C<0.000000e+0> instead of C<0.000000e+00>. + +For tests 129 and 130, the failing platforms do not comply with +the ANSI C Standard: lines 19ff on page 134 of ANSI X3.159 1989, to +be exact. (They produce something other than "1" and "-1" when +formatting 0.6 and -0.6 using the printf format "%.0f"; most often, +they produce "0" and "-0".) + +=head2 SCO + +The socketpair tests are known to be unhappy in SCO 3.2v5.0.4: + + ext/Socket/socketpair.t...............FAILED tests 15-45 + +=head2 Solaris 2.5 + +In case you are still using Solaris 2.5 (aka SunOS 5.5), you may +experience failures (the test core dumping) in lib/locale.t. +The suggested cure is to upgrade your Solaris. + +=head2 Solaris x86 Fails Tests With -Duse64bitint + +The following tests are known to fail in Solaris x86 with Perl +configured to use 64 bit integers: + + ext/Data/Dumper/t/dumper.............FAILED at test 268 + ext/Devel/Peek/Peek..................FAILED at test 7 + +=head2 SUPER-UX (NEC SX) + +The following tests are known to fail on SUPER-UX: + + op/64bitint...........................FAILED tests 29-30, 32-33, 35-36 + op/arith..............................FAILED tests 128-130 + op/pack...............................FAILED tests 25-5625 + op/pow................................ + op/taint..............................# msgsnd failed + ../ext/IO/lib/IO/t/io_poll............FAILED tests 3-4 + ../ext/IPC/SysV/ipcsysv...............FAILED tests 2, 5-6 + ../ext/IPC/SysV/t/msg.................FAILED tests 2, 4-6 + ../ext/Socket/socketpair..............FAILED tests 12 + ../lib/IPC/SysV.......................FAILED tests 2, 5-6 + ../lib/warnings.......................FAILED tests 115-116, 118-119 + +The op/pack failure ("Cannot compress negative numbers at op/pack.t line 126") +is serious but as of yet unsolved. It points at some problems with the +signedness handling of the C compiler, as do the 64bitint, arith, and pow +failures. Most of the rest point at problems with SysV IPC. + +=head2 Term::ReadKey not working on Win32 + +Use Term::ReadKey 2.20 or later. + +=head2 UNICOS/mk + +=over 4 + +=item * + +During Configure, the test + + Guessing which symbols your C compiler and preprocessor define... + +will probably fail with error messages like + + CC-20 cc: ERROR File = try.c, Line = 3 + The identifier "bad" is undefined. + + bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K + ^ + + CC-65 cc: ERROR File = try.c, Line = 3 + A semicolon is expected at this point. + +This is caused by a bug in the awk utility of UNICOS/mk. You can ignore +the error, but it does cause a slight problem: you cannot fully +benefit from the h2ph utility (see L<h2ph>) that can be used to +convert C headers to Perl libraries, mainly used to be able to access +from Perl the constants defined using C preprocessor, cpp. Because of +the above error, parts of the converted headers will be invisible. +Luckily, these days the need for h2ph is rare. + +=item * + +If building Perl with interpreter threads (ithreads), the +getgrent(), getgrnam(), and getgrgid() functions cannot return the +list of the group members due to a bug in the multithreaded support of +UNICOS/mk. What this means is that in list context the functions will +return only three values, not four. + +=back + +=head2 UTS + +There are a few known test failures, see L<perluts> (README.uts). + +=head2 VOS (Stratus) + +When Perl is built using the native build process on VOS Release +14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted tests either +pass or result in TODO (ignored) failures. + +=head2 VMS + +There should be no reported test failures with a default configuration, +though there are a number of tests marked TODO that point to areas +needing further debugging and/or porting work. + +=head2 Win32 + +In multi-CPU boxes, there are some problems with the I/O buffering: +some output may appear twice. + +=head2 XML::Parser not working + +Use XML::Parser 2.31 or later. + +=head2 z/OS (OS/390) + +z/OS has rather many test failures but the situation is actually much +better than it was in 5.6.0; it's just that so many new modules and +tests have been added. + + Failed Test Stat Wstat Total Fail Failed List of Failed + --------------------------------------------------------------------------- + ../ext/Data/Dumper/t/dumper.t 357 8 2.24% 311 314 325 327 + 331 333 337 339 + ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5 + ../ext/Storable/t/downgrade.t 12 3072 169 12 7.10% 14-15 46-47 78-79 + 110-111 150 161 + ../lib/ExtUtils/t/Constant.t 121 30976 48 48 100.00% 1-48 + ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9 + op/pat.t 922 7 0.76% 665 776 785 832- + 834 845 + op/sprintf.t 224 3 1.34% 98 100 136 + op/tr.t 97 5 5.15% 63 71-74 + uni/fold.t 780 6 0.77% 61 169 196 661 + 710-711 + +The failures in dumper.t and downgrade.t are problems in the tests, +those in io_unix and sprintf are problems in the USS (UDP sockets and +printf formats). The pat, tr, and fold failures are genuine Perl +problems caused by EBCDIC (and in the pat and fold cases, combining +that with Unicode). The Constant and Embed are probably problems in +the tests (since they test Perl's ability to build extensions, and +that seems to be working reasonably well.) + +=head2 Unicode Support on EBCDIC Still Spotty + +Though mostly working, Unicode support still has problem spots on +EBCDIC platforms. One such known spot are the C<\p{}> and C<\P{}> +regular expression constructs for code points less than 256: the +C<pP> are testing for Unicode code points, not knowing about EBCDIC. + +=head2 Seen In Perl 5.7 But Gone Now + +C<Time::Piece> (previously known as C<Time::Object>) was removed +because it was felt that it didn't have enough value in it to be a +core module. It is still a useful module, though, and is available +from the CPAN. + +Perl 5.8 unfortunately does not build anymore on AmigaOS; this broke +accidentally at some point. Since there are not that many Amiga +developers available, we could not get this fixed and tested in time +for 5.8.0. Perl 5.6.1 still works for AmigaOS (as does the 5.7.2 +development release). + +The C<PerlIO::Scalar> and C<PerlIO::Via> (capitalised) were renamed as +C<PerlIO::scalar> and C<PerlIO::via> (all lowercase) just before 5.8.0. +The main rationale was to have all core PerlIO layers to have all +lowercase names. The "plugins" are named as usual, for example +C<PerlIO::via::QuotedPrint>. + +The C<threads::shared::queue> and C<threads::shared::semaphore> were +renamed as C<Thread::Queue> and C<Thread::Semaphore> just before 5.8.0. +The main rationale was to have thread modules to obey normal naming, +C<Thread::> (the C<threads> and C<threads::shared> themselves are +more pragma-like, they affect compile-time, so they stay lowercase). + +=head1 Reporting Bugs + +If you find what you think is a bug, you might check the articles +recently posted to the comp.lang.perl.misc newsgroup and the perl +bug database at http://bugs.perl.org/ . There may also be +information at http://www.perl.com/ , the Perl Home Page. + +If you believe you have an unreported bug, please run the B<perlbug> +program included with your release. Be sure to trim your bug down +to a tiny but sufficient test case. Your bug report, along with the +output of C<perl -V>, will be sent off to perlbug@perl.org to be +analysed by the Perl porting team. + +=head1 SEE ALSO + +The F<Changes> file for exhaustive details on what changed. + +The F<INSTALL> file for how to build Perl. + +The F<README> file for general stuff. + +The F<Artistic> and F<Copying> files for copyright information. + +=head1 HISTORY + +Written by Jarkko Hietaniemi <F<jhi@iki.fi>>. + +=cut |