perldelta - what is new for perl v5.8.0
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.
If you are upgrading from Perl 5.005_03, you might also want to read perl56delta.
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 (like modperl) tend to prefer the system malloc. Such platforms include Alpha and 64-bit HPPA, MIPS, PPC, and Sparc.
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 modperl which are using the AIX native interface.
my variables now handled at run-time.The my EXPR : ATTRS syntax now applies variable attributes at run-time.
(Subroutine and our variables still get attributes applied at compile-time.) See attributes for additional details.
In particular,
however,
this allows variable attributes to be useful for 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).
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.
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.
Unicode scripts are now supported. Scripts are similar to (and superior to) Unicode 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 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 Latin).
A number of other properties are now supported,
including \p{L&},
\p{Any} \p{Assigned},
\p{Unassigned},
\p{Blank} and \p{SpacePerl} (along with their \P{...} versions,
of course).
See perlunicode for details,
and more additions.
The In or Is prefix to names used with the \p{...} and \P{...} are now almost always optional.
The only exception is that a In prefix is required to signify a Unicode block when a block name conflicts with a script name.
For example,
\p{Tibetan} refers to the script,
while \p{InTibetan} refers to the block.
When there is no name conflict,
you can omit the In from the block name (e.g.
\p{BraillePatterns}),
but to be safe,
it's probably best to always use the In).
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.
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().
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 f/d, but you never knew that.)
CORE::dump(),
but in future releases the behaviour of an unqualified dump() call may change.\w character.package; syntax (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,
use strict; instead.fields pragma interface will remain available.@a->[...] and %h->{...} have now been deprecated.open($fh,'>:crlf :utf8', $path) || ...
or on already opened handles via extended binmode:
binmode($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 "Installation and Configuration Improvements" for the effects of PerlIO on your architecture name.
open($fh,">:utf8","Uni.txt");
Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named for you since it's not UTF-8 what you will be getting but instead UTF-EBCDIC. See perlunicode, utf8, and http://www.unicode.org/unicode/reports/tr16/ for more information. In future releases this naming may change.
open($fh,'>', \$variable) || ...
open($fh,"+>", undef) || ...
That is a literal undef, not an undefined value.
open is now implemented for pipes (at least on UNIX):
open($fh,"-|", 'cat', '/etc/motd')
creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in the child process.
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.
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.
\s (\p{Space} isn't, since that includes the vertical tabulator character, whereas \s doesn't.)
See "New Unicode Properties" earlier in this document for additional information on changes with Unicode properties.
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 strtoul() and 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.)
perl -d:Module=arg,arg,arg now works (previously one couldn't pass in multiple arguments.)dump() better written as CORE::dump(), meaning that by default dump(...) is resolved as the builtin dump() which dumps core and aborts, not as (possibly) user-defined sub dump. To call the latter, qualify the call as &dump(...). (The whole dump() feature is to considered deprecated, and possibly removed/changed in future releases.)undef in list context. However, the lvalue subroutine feature still remains experimental.$^N, which contains the most-recently closed group (submatch).no Module; now works even if there is no "sub unimport" in the Module.undef if either operand is a NaN. Previously the behaviour was unspecified.pack() / unpack() now can group template letters with () and then apply repetition/count modifiers on the groups.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 j, J, F, and D.pack('U0a*', ...) can now be used to force a string to UTF8.%\d+\$ and *\d+\$ syntaxes. For example
print "%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.
-t is available. It is the little brother of -T: instead of dieing on taint violations, lexical warnings are given. This is only meant as a temporary debugging aid while securing the code of old legacy applications. This is not a substitute for -T.exec LIST and system LIST have now been considered too risky (think exec @ARGV: it can start any program with any arguments), and now the said forms cause a warning. 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.utime undef, undef, @files to change the file timestamps to the current time.Attribute::Handlers 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).
Class::ISA for reporting the search path for a class's ISA tree, by Sean Burke, has been added. See Class::ISA.Cwd has now 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.Devel::PPPort, originally from Kenneth Albanowski and now maintained by Paul Marquess, has been added. It is primarily used by h2xs to enhance portability of XS modules between different versions of Perl.Digest, frontend module for calculating digests (checksums), from Gisle Aas, has been added. See Digest.Digest::MD5 for calculating MD5 digests (checksums) as defined in RFC 1321, from Gisle Aas, has been added. See Digest::MD5.
use Digest::MD5 'md5_hex';
$digest = md5_hex("Thirsty Camel");
print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
NOTE: the MD5 backward compatibility module is deliberately not included since its further use is discouraged.
Encode, by Nick Ing-Simmons, provides a mechanism to translate between different character encodings. Support for Unicode, ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are compiled in to the module. Several other encodings (like Japanese, Chinese, and MacIntosh encodings) are included and will be loaded at runtime. See Encode.
Any encoding supported by Encode module is also available to the ":encoding()" layer if PerlIO is used.
I18N::Langinfo can be use to query locale information. See I18N::Langinfo.I18N::LangTags has functions for dealing with RFC3066-style language tags, by Sean Burke. See I18N::LangTags.ExtUtils::Constant is a new tool for extension writers for generating XS code to import C header constants, by Nicholas Clark. See ExtUtils::Constant.Filter::Simple is an easy-to-use frontend to Filter::Util::Call, from Damian Conway. See Filter::Simple.
# in MyFilter.pm:
package MyFilter;
use Filter::Simple sub {
while (my ($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"
File::Temp allows one to create temporary files and directories in an easy, portable, and secure way, by Tim Jenness. See File::Temp.Filter::Util::Call provides you with the framework to write Source Filters in Perl, from Paul Marquess. For most uses the frontend Filter::Simple is to be preferred. See Filter::Util::Call.if is a new pragma for conditional inclusion of modules, from Ilya Zakharevich.Perl installation leaves libnet unconfigured, use libnetcfg to configure.
List::Util is a selection of general-utility list subroutines, like sum(), min(), first(), and shuffle(), by Graham Barr. See List::Util.Locale::Constants, Locale::Country, Locale::Currency, and Locale::Language, from Neil Bowers, have been added. They provide the codes for various locale standards, such as "fr" for France, "usd" for US Dollar, and "jp" for Japanese.
use Locale::Country;
$country = code2country('jp'); # $country gets 'Japan'
$code = country2code('Norway'); # $code gets 'no'
See Locale::Constants, Locale::Country, Locale::Currency, and Locale::Language.
Locale::Maketext is localization framework from Sean Burke. See Locale::Maketext, and Locale::Maketext::TPJ13. The latter is an article about software localization, originally published in The Perl Journal #13, republished here with kind permission.Memoize can make your functions faster by trading space for time, from Mark-Jason Dominus. See Memoize.MIME::Base64 allows you to encode data in base64, from Gisle Aas, as defined in RFC 2045 - MIME (Multipurpose Internet Mail Extensions).
use MIME::Base64;
$encoded = encode_base64('Aladdin:open sesame');
$decoded = decode_base64($encoded);
print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
See MIME::Base64.
MIME::QuotedPrint allows you to encode data in quoted-printable encoding, as defined in RFC 2045 - MIME (Multipurpose Internet Mail Extensions), from Gisle Aas.
use MIME::QuotedPrint;
$encoded = encode_qp("Smiley in Unicode: \x{263a}");
$decoded = decode_qp($encoded);
print $encoded, "\n"; # "Smiley in Unicode: =263A"
MIME::QuotedPrint has been enhanced to provide the basic methods necessary to use it with PerlIO::Via as in :
use MIME::QuotedPrint;
open($fh,">Via(MIME::QuotedPrint)",$path);
See MIME::QuotedPrint.
NEXT is pseudo-class for method redispatch, from Damian Conway. See NEXT.open is a new pragma for setting the default I/O disciplines for open().PerlIO::Scalar provides the implementation of IO to "in memory" Perl scalars as discussed above, from Nick Ing-Simmons. It also serves as an example of a loadable PerlIO layer. Other future possibilities include PerlIO::Array and PerlIO::Code. See PerlIO::Scalar.PerlIO::Via acts as a PerlIO layer and wraps PerlIO layer functionality provided by a class (typically implemented in perl code), from Nick Ing-Simmons.
use MIME::QuotedPrint;
open($fh,">Via(MIME::QuotedPrint)",$path);
This will automatically convert everything output to $fh to Quoted-Printable. See PerlIO::Via.
Pod::ParseLink, by Russ Allbery, has been added, to parse L<> links in pods as described in the new perlpodspec.Pod::Text::Overstrike, by Joe Smith, has been added. It converts POD data to formatted overstrike text. See Pod::Text::Overstrike.Scalar::Util is a selection of general-utility scalar subroutines, like blessed(), reftype(), and tainted(). See Scalar::Util.sort is a new pragma for controlling the behaviour of sort().Storable gives persistence to Perl data structures by allowing the storage and retrieval of Perl data to and from files in a fast and compact binary format, from Raphael Manfredi. See Storable.Switch, from Damian Conway, has been added. Just by saying
use Switch;
you have switch and case available in Perl.
use Switch;
switch ($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 Switch.
Test::More is yet another framework for writing test scripts, more extensive than Test::Simple, by Michael Schwern. See Test::More.Test::Simple has basic utilities for writing tests, by Michael Schwern. See Test::Simple.Text::Balanced has been added, for extracting delimited text sequences from strings, from Damian Conway.
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 Text::Balanced.
threads is an interface to interpreter threads, by Arthur Bergman. 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 fork() emulation). See threads.threads::shared allows data sharing for interpreter threads, from Arthur Bergman. In the ithreads model any data sharing between threads must be explicit, as opposed to the old 5.005 thread model where data sharing was implicit. See threads::shared.Tie::File, by Mark-Jason Dominus, associates a Perl array with the lines of a file.Tie::Memoize, by Ilya Zakharevich, provides on-demand loaded hashes.Tie::RefHash::Nestable, by Edward Avis, allows storing hash references (unlike the standard Tie::RefHash) The module is contained within Tie::RefHash, see Tie::RefHash.Time::HiRes provides high resolution timing (ualarm, usleep, and gettimeofday), from Douglas E. Wegscheid. See Time::HiRes.Unicode::UCD offers a querying interface to the Unicode Character Database. See Unicode::UCD.Unicode::Collate implements the UCA (Unicode Collation Algorithm) for sorting Unicode strings, by SADAHIRO Tomoyuki. See Unicode::Collate.Unicode::Normalize implements the various Unicode normalization forms, by SADAHIRO Tomoyuki. See Unicode::Normalize.XS::Typemap, by Tim Jenness, is a test extension that exercises XS typemaps. Nothing gets installed but for extension writers the code is worth studying.no AutoLoader;.use English '-no_match_vars';
(Assuming, of course, that one doesn't need the troublesome variables $`, $&, or $'.) Also, introduced @LAST_MATCH_START and @LAST_MATCH_END English aliases for @- and @+.
GLOB_LIMIT constant to limit the size of the returned list of filenames.LocalPort of zero (usually meaning that the operating system will make one up.)%INC now localised in a Safe compartment so that use/require work.our() does not and will not support.)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.h2ph now supports C trigraphs.h2xs now produces a template README.h2xs now uses Devel::PPort for better portability between different versions of Perl.h2xs uses the new 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 never gets 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). h2xs now also supports C trigraphs.libnetcfg has been added to configure the libnet.perlbug is now much more robust. It also sends the bug report to perl.org, not perl.com.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 perlcc -B instead.)perlivp is a new Installation Verification Procedure utility for running any time after installing Perl.pod2html now allows specifying a cache directory.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 psed utility.)xsubpp now understands POD documentation embedded in the *.xs files.xsubpp now supports OUT keyword.The following platform-specific documents are available before the installation as README.platform, and after the installation as perlplatform:
perlaix perlamiga perlapollo perlbeos perlbs2000
perlce perlcygwin perldgux perldos perlepoc perlhpux
perlhurd perlmachten perlmacos perlmint perlmpeix
perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
perltru64 perluts perlvmesa perlvms perlvos perlwin32
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 1 comes first is hard to know, since one 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, 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 $N doesn't just double the quicksort time, it quadruples it. Quicksort has a worst case run time that can grow like N**2, so-called quadratic behaviour, and it can happen on patterns that may well arise in normal use. You won't notice this for small arrays, but you will notice it with larger arrays, and you may not live long enough for the sort to complete on arrays of a million elements. So the 5.8 quicksort scrambles large arrays before sorting them, as a statistical defence against quadratic behaviour. But that means if you sort the same large array twice, ties may be broken in different ways.
Because of the unpredictability of tie-breaking order, and the quadratic worst-case behaviour, quicksort was almost replaced completely with a stable mergesort. Stable means that ties are broken to preserve the original order of appearance in the input array. So
sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);
will yield (4,3,1,1,5,9), guaranteed. The even and odd numbers appear in the output in the same order they appeared in the input. Mergesort has worst case O(NlogN) behaviour, the best value attainable. And, ironically, this mergesort does particularly well where quicksort goes quadratic: mergesort sorts (1..$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 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 stable subpragma forces stable behaviour, regardless of algorithm. The _quicksort and _mergesort subpragmas are heavy-handed ways to select the underlying implementation. The leading _ 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.
-S can now run non-interactively.-Dafsroot=/some/where/else.@Config{qw(db_version_major db_version_minor db_version_patch)} from Perl and as DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG DB_VERSION_PATCH_CFG from C. mkdir /tmp/perl/build/directory
cd /tmp/perl/build/directory
sh /path/to/perl/source/Configure -Dmksymlinks ...
This will create in /tmp/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 /tmp/perl/build/directory.
Configure -Duseithreads) because it wouldn't work anyway (the Thread extension requires being Configured with -Duse5005threads).
But note that the Thread.pm interface is now shared by both thread models.
For the list of platforms known to support Perl, see "Supported Platforms" in perlport.
Numerous memory leaks and uninitialized memory accesses have been hunted down. Most importantly anonymous subs used to leak quite a bit.
"0" now treated correctly, the d command now checks line number, the $. no longer gets corrupted, all debugger output now goes correctly to the socket if RemotePort is set.*foo{FORMAT} now works. =item *
Infinity is now recognized as a number.
eval "...".use warnings qw(FATAL all) did not work as intended. This has been corrected.#line now works.-Duselongdouble. This version of Perl detects this brokenness and has a workaround for it. The glibc release 2.2.2 is known to have fixed the modfl() bug.qw(a\\b) now parses correctly as 'a\\b'.[[:space:]] to include the (very rarely used) vertical tab character. Added a new POSIX-ish character class [[:blank:]] which stands for horizontal whitespace (currently, the space and the tab).use re 'debug' or via -Dr) now looks better."a\nxb\n" =~ /(?!\A)x/m were flawed. The bug has been fixed.${$num}) was accidentally disabled. This works again now.LOG_AUTH constant.IsAlnum, IsAlpha, and IsWord now match titlecase.. operator or via variable interpolation, eq, substr, reverse, quotemeta, the x operator, substitution with s///, single-quoted UTF8, should now work.tr/// operator now works. Note that the tr///CU functionality has been removed (but see pack('U0', ...)).eval "v200" now works.IsDigit.Perl now works on post-4.0 BSD/OSes.
Setting $0 now works (as much as possible; see perlvar for details).
Numerous updates; currently synchronised with Cygwin 1.1.4.
EPOC update after Perl 5.6.0. See README.epoc.
Perl now works on post-3.0 FreeBSDs.
README.hpux updated; Configure -Duse64bitall now almost works.
Numerous compilation flag and hint enhancements; accidental mixing of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
Compilation of the standard Perl distribution in MacOS 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.
MPE/iX update after Perl 5.6.0. See README.mpeix.
Perl now works on NetBSD/sparc.
Now works with usethreads (see INSTALL).
64-bitness using the Sun Workshop compiler now works.
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.
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.
chdir() now works better despite a CRT bug; now works with MULTIPLICITY (see INSTALL); now works with Perl's malloc.
The tainting of %ENV elements via keys or values was previously unimplemented. It now works as documented.
The 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. The most significant enhancement is that we can now usually get the completion status of a terminated process.
POSIX-style signals are now emulated much better on VMS versions prior to 7.0.
The system function and backticks operator have improved functionality and better error handling.
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.
File::Spec->tmpdir() now prefers C:/temp over /tmp (works better when perl is running as service).<-- HERE marker.main:: prefix for filehandles in the main package, for example STDIN instead of main::STDIN.\8, \9, and \_. There is no need to escape any of the \w characters.See perldebug
push @a; and unshift @a; (with no values to push or unshift) now give a warning. This may be a problem for generated and evaled code."C" format you will get an optional warning. Similarly for the "c" format and a number less than -128 or more than 127.(?o) make sense only if applied to the entire regex. You will an optional warning if you try to do otherwise.%foo->{bar} has been deprecated for a while. Now you will get an optional warning.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.'P') have been macrofied (e.g. PERL_MAGIC_TIED) for better source code readability and maintainability.offsets member of the struct regexp. See perldebguts for more complete information.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.(This change was already made in 5.7.0 but bears repeating here.)
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/).
Several new tests have been added, especially for the lib subsection. There are now about 34 000 individual tests (spread over about 530 test scripts), in the regression suite (5.6.1 has about 11700 tests, in 258 test scripts) Many of the new tests are 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. In a really fast machine you can hope to finish the suite in about 5 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.)
The AIX C compiler vac version 5.0.0.0 may produce buggy code, resulting in few random tests failing, 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.
One cannot call Perl using the volume: syntax, that is, perl -v works, but for example bin:perl -v doesn't. The exact reason isn't known but the current suspect is the ixemul library.
Don't panic. Read INSTALL 'make test' section instead.
The subtests 11 and 12 sometimes fail and sometimes work.
lib/File/Spec/t/rel2abs2rel.t tests that "`` works" by running a a perl 1 liner in backticks, using "$^X" as the path to perl. It is failing on FreeBSD 4.5, but only when run as part of make test. This seems to be a kernel problem rather than perl - reading the symlink /proc/curproc/file returns "unknown" rather than the path to perl, and a kernel debugger reveals that variable numfullpathfail2 in /usr/src/sys/kern/vfs_cache.c is being incremented whenever /proc/curproc/file fails to return the perl executable's path.
The lib/io_multihomed test may hang in HP-UX if Perl has been configured to be 64-bit. Because other 64-bit platforms do not hang in this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The test attempts to create and connect to "multihomed" sockets (sockets which have multiple IP addresses).
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.
No known fix.
The following tests are known to fail:
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 ../ext/POSIX/t/posix.t 31 1 3.23% 10
OS/390 has rather many test failures but the situation is actually better than it was in 5.6.0, it's just that so many new modules and tests have been added.
Failed 10/611 test scripts, 98.36% okay. 72/53809 subtests failed, 99.87% okay. Failed Test Stat Wstat Total Fail Failed List of Failed ------------------------------------------------------------------------------- ../ext/B/t/deparse.t 17 1 5.88% 14 ../ext/IO/lib/IO/t/io_unix.t 5 4 80.00% 2-5 ../lib/utf8.t 94 13 13.83% 27 30-31 43 46 73 76 79 82 85 88 91 94 ../lib/Benchmark.t 1 256 159 1 0.63% 75 ../lib/ExtUtils/t/Embed.t 9 9 100.00% 1-9 ../lib/ExtUtils/t/ExtUtils.t 27 19 70.37% 5-23 op/pat.t 858 9 1.05% 242-243 665 776 785 832-834 845 op/sprintf.t 224 3 1.34% 98 100 136 op/tr.t 97 5 5.15% 63 71-74 uni/fold.t 767 8 1.04% 25-26 62 169 196 648 697-698 57 tests and 377 subtests skipped.
The op/sprintf tests 129 and 130 are known to fail on some platforms. Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX. The failing platforms do not comply with the ANSI C Standard, line 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".)
Note that support for 5.005-style threading remains experimental and practically unsupported.
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/List/Util/t/first 2 lib/autouse 4 ext/Thread/thr5005 19-20
These failures are unlikely to get fixed as the 5.005-style threads are considered fundamentally broken.
../ext/Socket/socketpair.t 1 256 45 1 2.22% 12 ../lib/Math/Trig.t 26 1 3.85% 25 ../lib/warnings.t 460 1 0.22% 425 io/fs.t 36 1 2.78% 31 op/numconvert.t 1440 13 0.90% 208 509-510 657-658 665-666 829-830 989-990 1149-1150
The io/fs test #31 is failing because in UNICOS and UNICOS/mk truncate() cannot be used to grow the size of filehandles, only to reduce the size. The workaround is to truncate files instead of filehandles.
There are a few known test failures, see perluts.
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.
In multi-CPU boxes there are some problems with the I/O buffering: some output may appear twice. The Win32 following failures are known as of 5.7.3:
..\ext/Encode/t/JP.t 4 1024 22 4 18.18% 9 14 18 21 ..\ext/threads/t/end.t 6 4 66.67% 3-6 ..\lib/blib.t 3 768 7 3 42.86% 1 4-5
use Tie::Hash;
tie my %tie_hash => 'Tie::StdHash';
...
local($tie_hash{Foo}) = 1; # leaks
Code like the above is known to leak memory every time the local() is executed.
local %tied_array;
doesn't work as one would expect: the old value is restored incorrectly.
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 for now forbidden (you will get a fatal error even from an attempt).
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 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) link together at all binaries with different ideas about file offsets, all this is platform-dependent.
Though mostly working, Unicode support still has problem spots on EBCDIC platforms. One such known spot are the \p{} and \P{} regular expression constructs for code points less than 256: the pP are testing for Unicode code points, not knowing about EBCDIC.
The compiler suite is slowly getting better but it continues to be highly experimental. Use in production environments is discouraged.
The ability to configure Perl's numbers to use "long doubles", floating point numbers of hopefully better accuracy, is still experimental. The implementations of long doubles are not yet widespread and the existing implementations are not quite mature or standardised, therefore trying to support them is a rare and moving target. The gain of more precision may also be offset by slowdown in computations (more bits to move around, and the operations are more likely to be executed by less optimised libraries).
Time::Piece (previously known as 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.
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 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 perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
Written by Jarkko Hietaniemi <jhi@iki.fi>.
