perl590delta
(1)
Name
perl590delta - what is new for perl v5.9.0
Synopsis
Please see following description for synopsis
Description
Perl Programmers Reference Guide PERL590DELTA(1)
NAME
perl590delta - what is new for perl v5.9.0
DESCRIPTION
This document describes differences between the 5.8.0
release and the 5.9.0 release.
Incompatible Changes
Hash Randomisation
Mainly due to security reasons, the "random ordering" of
hashes has been made even more random. Previously while the
order of hash elements from keys(), values(), and each() was
essentially random, it was still repeatable. Now, however,
the order varies between different runs of Perl.
Perl has never guaranteed any ordering of the hash keys, and
the ordering has already changed several times during the
lifetime of Perl 5. Also, the ordering of hash keys has
always been, and continues to be, affected by the insertion
order.
The added randomness may affect applications.
One possible scenario is when output of an application has
included hash data. For example, if you have used the
Data::Dumper module to dump data into different files, and
then compared the files to see whether the data has changed,
now you will have false positives since the order in which
hashes are dumped will vary. In general the cure is to sort
the keys (or the values); in particular for Data::Dumper to
use the "Sortkeys" option. If some particular order is
really important, use tied hashes: for example the
Tie::IxHash module which by default preserves the order in
which the hash elements were added.
More subtle problem is reliance on the order of "global
destruction". That is what happens at the end of execution:
Perl destroys all data structures, including user data. If
your destructors (the DESTROY subroutines) have assumed any
particular ordering to the global destruction, there might
be problems ahead. For example, in a destructor of one
object you cannot assume that objects of any other class are
still available, unless you hold a reference to them. If
the environment variable PERL_DESTRUCT_LEVEL is set to a
non-zero value, or if Perl is exiting a spawned thread, it
will also destruct the ordinary references and the symbol
tables that are no longer in use. You can't call a class
method or an ordinary function on a class that has been
collected that way.
The hash randomisation is certain to reveal hidden
assumptions about some particular ordering of hash elements,
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and outright bugs: it revealed a few bugs in the Perl core
and core modules.
To disable the hash randomisation in runtime, set the
environment variable PERL_HASH_SEED to 0 (zero) before
running Perl (for more information see "PERL_HASH_SEED" in
perlrun), or to disable the feature completely in compile
time, compile with "-DNO_HASH_SEED" (see INSTALL).
See "Algorithmic Complexity Attacks" in perlsec for the
original rationale behind this change.
UTF-8 On Filehandles No Longer Activated By Locale
In Perl 5.8.0 all filehandles, including the standard
filehandles, were implicitly set to be in Unicode UTF-8 if
the locale settings indicated the use of UTF-8. This
feature caused too many problems, so the feature was turned
off and redesigned: see "Core Enhancements".
Single-number v-strings are no longer v-strings before "=>"
The version strings or v-strings (see "Version Strings" in
perldata) feature introduced in Perl 5.6.0 has been a source
of some confusion-- especially when the user did not want to
use it, but Perl thought it knew better. Especially
troublesome has been the feature that before a "=>" a
version string (a "v" followed by digits) has been
interpreted as a v-string instead of a string literal. In
other words:
%h = ( v65 => 42 );
has meant since Perl 5.6.0
%h = ( 'A' => 42 );
(at least in platforms of ASCII progeny) Perl 5.8.1
restored the more natural interpretation
%h = ( 'v65' => 42 );
The multi-number v-strings like v65.66 and 65.66.67 still
continue to be v-strings in Perl 5.8.
(Win32) The -C Switch Has Been Repurposed
The -C switch has changed in an incompatible way. The old
semantics of this switch only made sense in Win32 and only
in the "use utf8" universe in 5.6.x releases, and do not
make sense for the Unicode implementation in 5.8.0. Since
this switch could not have been used by anyone, it has been
repurposed. The behavior that this switch enabled in 5.6.x
releases may be supported in a transparent, data-dependent
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fashion in a future release.
For the new life of this switch, see "UTF-8 no longer
default under UTF-8 locales", and "-C" in perlrun.
(Win32) The /d Switch Of cmd.exe
Since version 5.8.1, perl uses the /d switch when running
the cmd.exe shell internally for system(), backticks, and
when opening pipes to external programs. The extra switch
disables the execution of AutoRun commands from the
registry, which is generally considered undesirable when
running external programs. If you wish to retain
compatibility with the older behavior, set PERL5SHELL in
your environment to "cmd /x/c".
The $* variable has been removed
$*, which was deprecated in favor of the "/s" and "/m"
regexp modifiers, has been removed.
Core Enhancements
Assertions
Perl 5.9.0 has experimental support for assertions. Note
that the user interface is not fully stabilized yet, and it
may change until the 5.10.0 release. A new command-line
switch, -A, is used to activate assertions, which are
declared with the "assertions" pragma. See assertions.
Defined-or operators
A new operator "//" (defined-or) has been implemented. The
following statement:
$a // $b
is merely equivalent to
defined $a ? $a : $b
and
$c //= $d;
can be used instead of
$c = $d unless defined $c;
This operator has the same precedence and associativity as
"||". It has a low-precedence counterpart, "err", which has
the same precedence and associativity as "or". Special care
has been taken to ensure that those operators Do What You
Mean while not breaking old code, but some edge cases
involving the empty regular expression may now parse
differently. See perlop for details.
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UTF-8 no longer default under UTF-8 locales
In Perl 5.8.0 many Unicode features were introduced. One
of them was found to be of more nuisance than benefit: the
automagic (and silent) "UTF-8-ification" of filehandles,
including the standard filehandles, if the user's locale
settings indicated use of UTF-8.
For example, if you had "en_US.UTF-8" as your locale, your
STDIN and STDOUT were automatically "UTF-8", in other words
an implicit binmode(..., ":utf8") was made. This meant that
trying to print, say, chr(0xff), ended up printing the bytes
0xc3 0xbf. Hardly what you had in mind unless you were
aware of this feature of Perl 5.8.0. The problem is that
the vast majority of people weren't: for example in RedHat
releases 8 and 9 the default locale setting is UTF-8, so all
RedHat users got UTF-8 filehandles, whether they wanted it
or not. The pain was intensified by the Unicode
implementation of Perl 5.8.0 (still) having nasty bugs,
especially related to the use of s/// and tr///. (Bugs that
have been fixed in 5.8.1)
Therefore a decision was made to backtrack the feature and
change it from implicit silent default to explicit conscious
option. The new Perl command line option "-C" and its
counterpart environment variable PERL_UNICODE can now be
used to control how Perl and Unicode interact at interfaces
like I/O and for example the command line arguments. See
"-C" in perlrun and "PERL_UNICODE" in perlrun for more
information.
Unsafe signals again available
In Perl 5.8.0 the so-called "safe signals" were introduced.
This means that Perl no longer handles signals immediately
but instead "between opcodes", when it is safe to do so.
The earlier immediate handling easily could corrupt the
internal state of Perl, resulting in mysterious crashes.
However, the new safer model has its problems too. Because
now an opcode, a basic unit of Perl execution, is never
interrupted but instead let to run to completion, certain
operations that can take a long time now really do take a
long time. For example, certain network operations have
their own blocking and timeout mechanisms, and being able to
interrupt them immediately would be nice.
Therefore perl 5.8.1 introduced a "backdoor" to restore the
pre-5.8.0 (pre-5.7.3, really) signal behaviour. Just set
the environment variable PERL_SIGNALS to "unsafe", and the
old immediate (and unsafe) signal handling behaviour
returns. See "PERL_SIGNALS" in perlrun and "Deferred
Signals (Safe Signals)" in perlipc.
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In completely unrelated news, you can now use safe signals
with POSIX::SigAction. See "POSIX::SigAction" in POSIX.
Tied Arrays with Negative Array Indices
Formerly, the indices passed to "FETCH", "STORE", "EXISTS",
and "DELETE" methods in tied array class were always non-
negative. If the actual argument was negative, Perl would
call FETCHSIZE implicitly and add the result to the index
before passing the result to the tied array method. This
behaviour is now optional. If the tied array class contains
a package variable named $NEGATIVE_INDICES which is set to a
true value, negative values will be passed to "FETCH",
"STORE", "EXISTS", and "DELETE" unchanged.
local ${$x}
The syntaxes
local ${$x}
local @{$x}
local %{$x}
now do localise variables, given that the $x is a valid
variable name.
Unicode Character Database 4.0.0
The copy of the Unicode Character Database included in Perl
5.8 has been updated to 4.0.0 from 3.2.0. This means for
example that the Unicode character properties are as in
Unicode 4.0.0.
Miscellaneous Enhancements
"unpack()" now defaults to unpacking the $_.
"map" in void context is no longer expensive. "map" is now
context aware, and will not construct a list if called in
void context.
If a socket gets closed by the server while printing to it,
the client now gets a SIGPIPE. While this new feature was
not planned, it fell naturally out of PerlIO changes, and is
to be considered an accidental feature.
PerlIO::get_layers(FH) returns the names of the PerlIO
layers active on a filehandle.
PerlIO::via layers can now have an optional UTF8 method to
indicate whether the layer wants to "auto-:utf8" the stream.
utf8::is_utf8() has been added as a quick way to test
whether a scalar is encoded internally in UTF-8 (Unicode).
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Modules and Pragmata
Updated Modules And Pragmata
The following modules and pragmata have been updated since
Perl 5.8.0:
base
B::Bytecode
In much better shape than it used to be. Still far from
perfect, but maybe worth a try.
B::Concise
B::Deparse
Benchmark
An optional feature, ":hireswallclock", now allows for
high resolution wall clock times (uses Time::HiRes).
ByteLoader
See B::Bytecode.
bytes
Now has bytes::substr.
CGI
charnames
One can now have custom character name aliases.
CPAN
There is now a simple command line frontend to the
CPAN.pm module called cpan.
Data::Dumper
A new option, Pair, allows choosing the separator
between hash keys and values.
DB_File
Devel::PPPort
Digest::MD5
Encode
Significant updates on the encoding pragma functionality
(tr/// and the DATA filehandle, formats).
If a filehandle has been marked as to have an encoding,
unmappable characters are detected already during input,
not later (when the corrupted data is being used).
The ISO 8859-6 conversion table has been corrected (the
0x30..0x39 erroneously mapped to U+0660..U+0669, instead
of U+0030..U+0039). The GSM 03.38 conversion did not
handle escape sequences correctly. The UTF-7 encoding
has been added (making Encode feature-complete with
Unicode::String).
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fields
libnet
Math::BigInt
A lot of bugs have been fixed since v1.60, the version
included in Perl v5.8.0. Especially noteworthy are the
bug in Calc that caused div and mod to fail for some
large values, and the fixes to the handling of bad
inputs.
Some new features were added, e.g. the broot() method,
you can now pass parameters to config() to change some
settings at runtime, and it is now possible to trap the
creation of NaN and infinity.
As usual, some optimizations took place and made the
math overall a tad faster. In some cases, quite a lot
faster, actually. Especially alternative libraries like
Math::BigInt::GMP benefit from this. In addition, a lot
of the quite clunky routines like fsqrt() and flog() are
now much much faster.
MIME::Base64
NEXT
Diamond inheritance now works.
Net::Ping
PerlIO::scalar
Reading from non-string scalars (like the special
variables, see perlvar) now works.
podlators
Pod::LaTeX
PodParsers
Pod::Perldoc
Complete rewrite. As a side-effect, no longer refuses
to startup when run by root.
Scalar::Util
New utilities: refaddr, isvstring, looks_like_number,
set_prototype.
Storable
Can now store code references (via B::Deparse, so not
foolproof).
strict
Earlier versions of the strict pragma did not check the
parameters implicitly passed to its "import" (use) and
"unimport" (no) routine. This caused the false idiom
such as:
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use strict qw(@ISA);
@ISA = qw(Foo);
This however (probably) raised the false expectation
that the strict refs, vars and subs were being enforced
(and that @ISA was somehow "declared"). But the strict
refs, vars, and subs are not enforced when using this
false idiom.
Starting from Perl 5.8.1, the above will cause an error
to be raised. This may cause programs which used to
execute seemingly correctly without warnings and errors
to fail when run under 5.8.1. This happens because
use strict qw(@ISA);
will now fail with the error:
Unknown 'strict' tag(s) '@ISA'
The remedy to this problem is to replace this code with
the correct idiom:
use strict;
use vars qw(@ISA);
@ISA = qw(Foo);
Term::ANSIcolor
Test::Harness
Now much more picky about extra or missing output from
test scripts.
Test::More
Test::Simple
Text::Balanced
Time::HiRes
Use of nanosleep(), if available, allows mixing
subsecond sleeps with alarms.
threads
Several fixes, for example for join() problems and
memory leaks. In some platforms (like Linux) that use
glibc the minimum memory footprint of one ithread has
been reduced by several hundred kilobytes.
threads::shared
Many memory leaks have been fixed.
Unicode::Collate
Unicode::Normalize
Win32::GetFolderPath
Win32::GetOSVersion
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Now returns extra information.
Utility Changes
The "h2xs" utility now produces a more modern layout:
Foo-Bar/lib/Foo/Bar.pm instead of Foo/Bar/Bar.pm. Also, the
boilerplate test is now called t/Foo-Bar.t instead of t/1.t.
The Perl debugger (lib/perl5db.pl) has now been extensively
documented and bugs found while documenting have been fixed.
"perldoc" has been rewritten from scratch to be more robust
and feature rich.
"perlcc -B" works now at least somewhat better, while
"perlcc -c" is rather more broken. (The Perl compiler suite
as a whole continues to be experimental.)
New Documentation
perl573delta has been added to list the differences between
the (now quite obsolete) development releases 5.7.2 and
5.7.3.
perl58delta and perl581delta have been added: these are the
perldeltas of 5.8.0 and 5.8.1, detailing the differences
respectively between 5.6.0 and 5.8.0, and between 5.8.0 and
5.8.1.
perlartistic has been added: it is the Artistic License in
pod format, making it easier for modules to refer to it.
perlcheat has been added: it is a Perl cheat sheet.
perlgpl has been added: it is the GNU General Public License
in pod format, making it easier for modules to refer to it.
perlmacosx has been added to tell about the installation and
use of Perl in Mac OS X.
perlos400 has been added to tell about the installation and
use of Perl in OS/400 PASE.
perlreref has been added: it is a regular expressions quick
reference.
Installation and Configuration Improvements
The Unix standard Perl location, /usr/bin/perl, is no longer
overwritten by default if it exists. This change was very
prudent because so many Unix vendors already provide a
/usr/bin/perl, but simultaneously many system utilities may
depend on that exact version of Perl, so better not to
overwrite it.
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One can now specify installation directories for site and
vendor man and HTML pages, and site and vendor scripts. See
INSTALL.
One can now specify a destination directory for Perl
installation by specifying the DESTDIR variable for "make
install". (This feature is slightly different from the
previous "Configure -Dinstallprefix=...".) See INSTALL.
gcc versions 3.x introduced a new warning that caused a lot
of noise during Perl compilation: "gcc
-Ialreadyknowndirectory (warning: changing search order)".
This warning has now been avoided by Configure weeding out
such directories before the compilation.
One can now build subsets of Perl core modules by using the
Configure flags "-Dnoextensions=..." and
"-Donlyextensions=...", see INSTALL.
Platform-specific enhancements
In Cygwin Perl can now be built with threads ("Configure
-Duseithreads"). This works with both Cygwin 1.3.22 and
Cygwin 1.5.3.
In newer FreeBSD releases Perl 5.8.0 compilation failed
because of trying to use malloc.h, which in FreeBSD is just
a dummy file, and a fatal error to even try to use. Now
malloc.h is not used.
Perl is now known to build also in Hitachi HI-UXMPP.
Perl is now known to build again in LynxOS.
Mac OS X now installs with Perl version number embedded in
installation directory names for easier upgrading of user-
compiled Perl, and the installation directories in general
are more standard. In other words, the default installation
no longer breaks the Apple-provided Perl. On the other
hand, with "Configure -Dprefix=/usr" you can now really
replace the Apple-supplied Perl (please be careful).
Mac OS X now builds Perl statically by default. This change
was done mainly for faster startup times. The Apple-
provided Perl is still dynamically linked and shared, and
you can enable the sharedness for your own Perl builds by
"Configure -Duseshrplib".
Perl has been ported to IBM's OS/400 PASE environment. The
best way to build a Perl for PASE is to use an AIX host as a
cross-compilation environment. See README.os400.
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Yet another cross-compilation option has been added: now
Perl builds on OpenZaurus, an Linux distribution based on
Mandrake + Embedix for the Sharp Zaurus PDA. See the
Cross/README file.
Tru64 when using gcc 3 drops the optimisation for toke.c to
"-O2" because of gigantic memory use with the default "-O3".
Tru64 can now build Perl with the newer Berkeley DBs.
Building Perl on WinCE has been much enhanced, see README.ce
and README.perlce.
Selected Bug Fixes
Closures, eval and lexicals
There have been many fixes in the area of anonymous subs,
lexicals and closures. Although this means that Perl is now
more "correct", it is possible that some existing code will
break that happens to rely on the faulty behaviour. In
practice this is unlikely unless your code contains a very
complex nesting of anonymous subs, evals and lexicals.
Generic fixes
If an input filehandle is marked ":utf8" and Perl sees
illegal UTF-8 coming in when doing "<FH>", if warnings are
enabled a warning is immediately given - instead of being
silent about it and Perl being unhappy about the broken data
later. (The ":encoding(utf8)" layer also works the same
way.)
binmode(SOCKET, ":utf8") only worked on the input side, not
on the output side of the socket. Now it works both ways.
For threaded Perls certain system database functions like
getpwent() and getgrent() now grow their result buffer
dynamically, instead of failing. This means that at sites
with lots of users and groups the functions no longer fail
by returning only partial results.
Perl 5.8.0 had accidentally broken the capability for users
to define their own uppercase<->lowercase Unicode mappings
(as advertised by the Camel). This feature has been fixed
and is also documented better.
In 5.8.0 this
$some_unicode .= <FH>;
didn't work correctly but instead corrupted the data. This
has now been fixed.
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Tied methods like FETCH etc. may now safely access tied
values, i.e. resulting in a recursive call to FETCH etc.
Remember to break the recursion, though.
At startup Perl blocks the SIGFPE signal away since there
isn't much Perl can do about it. Previously this blocking
was in effect also for programs executed from within Perl.
Now Perl restores the original SIGFPE handling routine,
whatever it was, before running external programs.
Linenumbers in Perl scripts may now be greater than 65536,
or 2**16. (Perl scripts have always been able to be larger
than that, it's just that the linenumber for reported errors
and warnings have "wrapped around".) While scripts that
large usually indicate a need to rethink your code a bit,
such Perl scripts do exist, for example as results from
generated code. Now linenumbers can go all the way to
4294967296, or 2**32.
Platform-specific fixes
Linux
o Setting $0 works again (with certain limitations that
Perl cannot do much about: see "$0" in perlvar)
HP-UX
o Setting $0 now works.
VMS
o Configuration now tests for the presence of "poll()",
and IO::Poll now uses the vendor-supplied function if
detected.
o A rare access violation at Perl start-up could occur if
the Perl image was installed with privileges or if there
was an identifier with the subsystem attribute set in
the process's rightslist. Either of these circumstances
triggered tainting code that contained a pointer bug.
The faulty pointer arithmetic has been fixed.
o The length limit on values (not keys) in the %ENV hash
has been raised from 255 bytes to 32640 bytes (except
when the PERL_ENV_TABLES setting overrides the default
use of logical names for %ENV). If it is necessary to
access these long values from outside Perl, be aware
that they are implemented using search list logical
names that store the value in pieces, each 255-byte
piece (up to 128 of them) being an element in the search
list. When doing a lookup in %ENV from within Perl, the
elements are combined into a single value. The existing
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VMS-specific ability to access individual elements of a
search list logical name via the $ENV{'foo;N'} syntax
(where N is the search list index) is unimpaired.
o The piping implementation now uses local rather than
global DCL symbols for inter-process communication.
o File::Find could become confused when navigating to a
relative directory whose name collided with a logical
name. This problem has been corrected by adding
directory syntax to relative path names, thus preventing
logical name translation.
Win32
o A memory leak in the fork() emulation has been fixed.
o The return value of the ioctl() built-in function was
accidentally broken in 5.8.0. This has been corrected.
o The internal message loop executed by perl during
blocking operations sometimes interfered with messages
that were external to Perl. This often resulted in
blocking operations terminating prematurely or returning
incorrect results, when Perl was executing under
environments that could generate Windows messages. This
has been corrected.
o Pipes and sockets are now automatically in binary mode.
o The four-argument form of select() did not preserve $!
(errno) properly when there were errors in the
underlying call. This is now fixed.
o The "CR CR LF" problem of has been fixed, binmode(FH,
":crlf") is now effectively a no-op.
New or Changed Diagnostics
All the warnings related to pack() and unpack() were made
more informative and consistent.
Changed "A thread exited while %d threads were running"
The old version
A thread exited while %d other threads were still running
was misleading because the "other" included also the thread
giving the warning.
Removed "Attempt to clear a restricted hash"
It is not illegal to clear a restricted hash, so the warning
was removed.
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New "Illegal declaration of anonymous subroutine"
You must specify the block of code for "sub".
Changed "Invalid range "%s" in transliteration operator"
The old version
Invalid [] range "%s" in transliteration operator
was simply wrong because there are no "[] ranges" in tr///.
New "Missing control char name in \c"
Self-explanatory.
New "Newline in left-justified string for %s"
The padding spaces would appear after the newline, which is
probably not what you had in mind.
New "Possible precedence problem on bitwise %c operator"
If you think this
$x & $y == 0
tests whether the bitwise AND of $x and $y is zero, you will
like this warning.
New "read() on %s filehandle %s"
You cannot read() (or sysread()) from a closed or unopened
filehandle.
New "Tied variable freed while still in use"
Something pulled the plug on a live tied variable, Perl
plays safe by bailing out.
New "To%s: illegal mapping '%s'"
An illegal user-defined Unicode casemapping was specified.
New "Use of freed value in iteration"
Something modified the values being iterated over. This is
not good.
Changed Internals
These news matter to you only if you either write XS code or
like to know about or hack Perl internals (using Devel::Peek
or any of the "B::" modules counts), or like to run Perl
with the "-D" option.
The embedding examples of perlembed have been reviewed to be
up to date and consistent: for example, the correct use of
PERL_SYS_INIT3() and PERL_SYS_TERM().
Extensive reworking of the pad code (the code responsible
for lexical variables) has been conducted by Dave Mitchell.
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Extensive work on the v-strings by John Peacock.
UTF-8 length and position cache: to speed up the handling of
Unicode (UTF-8) scalars, a cache was introduced. Potential
problems exist if an extension bypasses the official APIs
and directly modifies the PV of an SV: the UTF-8 cache does
not get cleared as it should.
APIs obsoleted in Perl 5.8.0, like sv_2pv, sv_catpvn,
sv_catsv, sv_setsv, are again available.
Certain Perl core C APIs like cxinc and regatom are no
longer available at all to code outside the Perl core of the
Perl core extensions. This is intentional. They never
should have been available with the shorter names, and if
you application depends on them, you should (be ashamed and)
contact perl5-porters to discuss what are the proper APIs.
Certain Perl core C APIs like "Perl_list" are no longer
available without their "Perl_" prefix. If your XS module
stops working because some functions cannot be found, in
many cases a simple fix is to add the "Perl_" prefix to the
function and the thread context "aTHX_" as the first
argument of the function call. This is also how it should
always have been done: letting the Perl_-less forms to leak
from the core was an accident. For cleaner embedding you
can also force this for all APIs by defining at compile time
the cpp define PERL_NO_SHORT_NAMES.
Perl_save_bool() has been added.
Regexp objects (those created with "qr") now have S-magic
rather than R-magic. This fixed regexps of the form
/...(??{...;$x})/ to no longer ignore changes made to $x.
The S-magic avoids dropping the caching optimization and
making (??{...}) constructs obscenely slow (and consequently
useless). See also "Magic Variables" in perlguts.
Regexp::Copy was affected by this change.
The Perl internal debugging macros DEBUG() and DEB() have
been renamed to PERL_DEBUG() and PERL_DEB() to avoid
namespace conflicts.
"-DL" removed (the leaktest had been broken and unsupported
for years, use alternative debugging mallocs or tools like
valgrind and Purify).
Verbose modifier "v" added for "-DXv" and "-Dsv", see
perlrun.
New Tests
In Perl 5.8.0 there were about 69000 separate tests in about
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700 test files, in Perl 5.9.0 there are about 77000 separate
tests in about 780 test files. The exact numbers depend on
the Perl configuration and on the operating system platform.
Known Problems
The hash randomisation mentioned in "Incompatible Changes"
is definitely problematic: it will wake dormant bugs and
shake out bad assumptions.
Many of the rarer platforms that worked 100% or pretty close
to it with perl 5.8.0 have been left a little bit untended
since their maintainers have been otherwise busy lately, and
therefore there will be more failures on those platforms.
Such platforms include Mac OS Classic, IBM z/OS (and other
EBCDIC platforms), and NetWare. The most common Perl
platforms (Unix and Unix-like, Microsoft platforms, and VMS)
have large enough testing and expert population that they
are doing well.
Tied hashes in scalar context
Tied hashes do not currently return anything useful in
scalar context, for example when used as boolean tests:
if (%tied_hash) { ... }
The current nonsensical behaviour is always to return false,
regardless of whether the hash is empty or has elements.
The root cause is that there is no interface for the
implementors of tied hashes to implement the behaviour of a
hash in scalar context.
Net::Ping 450_service and 510_ping_udp failures
The subtests 9 and 18 of lib/Net/Ping/t/450_service.t, and
the subtest 2 of lib/Net/Ping/t/510_ping_udp.t might fail if
you have an unusual networking setup. For example in the
latter case the test is trying to send a UDP ping to the IP
address 127.0.0.1.
B::C
The C-generating compiler backend B::C (the frontend being
"perlcc -c") is even more broken than it used to be because
of the extensive lexical variable changes. (The good news
is that B::Bytecode and ByteLoader are better than they used
to be.)
Platform Specific Problems
EBCDIC Platforms
IBM z/OS and other EBCDIC platforms continue to be
problematic regarding Unicode support. Many Unicode tests
are skipped when they really should be fixed.
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Cygwin 1.5 problems
In Cygwin 1.5 the io/tell and op/sysio tests have failures
for some yet unknown reason. In 1.5.5 the threads tests
stress_cv, stress_re, and stress_string are failing unless
the environment variable PERLIO is set to "perlio" (which
makes also the io/tell failure go away).
Perl 5.8.1 does build and work well with Cygwin 1.3: with
(uname -a) "CYGWIN_NT-5.0 ... 1.3.22(0.78/3/2) 2003-03-18
09:20 i686 ..." a 100% "make test" was achieved with
"Configure -des -Duseithreads".
HP-UX: HP cc warnings about sendfile and sendpath
With certain HP C compiler releases (e.g. B.11.11.02) you
will get many warnings like this (lines wrapped for easier
reading):
cc: "/usr/include/sys/socket.h", line 504: warning 562:
Redeclaration of "sendfile" with a different storage class specifier:
"sendfile" will have internal linkage.
cc: "/usr/include/sys/socket.h", line 505: warning 562:
Redeclaration of "sendpath" with a different storage class specifier:
"sendpath" will have internal linkage.
The warnings show up both during the build of Perl and
during certain lib/ExtUtils tests that invoke the C
compiler. The warning, however, is not serious and can be
ignored.
IRIX: t/uni/tr_7jis.t falsely failing
The test t/uni/tr_7jis.t is known to report failure under
'make test' or the test harness with certain releases of
IRIX (at least IRIX 6.5 and MIPSpro Compilers Version
7.3.1.1m), but if run manually the test fully passes.
Mac OS X: no usemymalloc
The Perl malloc ("-Dusemymalloc") does not work at all in
Mac OS X. This is not that serious, though, since the
native malloc works just fine.
Tru64: No threaded builds with GNU cc (gcc)
In the latest Tru64 releases (e.g. v5.1B or later) gcc
cannot be used to compile a threaded Perl (-Duseithreads)
because the system "<pthread.h>" file doesn't know about
gcc.
Win32: sysopen, sysread, syswrite
As of the 5.8.0 release, sysopen()/sysread()/syswrite() do
not behave like they used to in 5.6.1 and earlier with
respect to "text" mode. These built-ins now always operate
in "binary" mode (even if sysopen() was passed the O_TEXT
flag, or if binmode() was used on the file handle). Note
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that this issue should only make a difference for disk
files, as sockets and pipes have always been in "binary"
mode in the Windows port. As this behavior is currently
considered a bug, compatible behavior may be re-introduced
in a future release. Until then, the use of sysopen(),
sysread() and syswrite() is not supported for "text" mode
operations.
TODO
Here are some things that are planned for perl 5.10.0 :
o Various Copy-On-Write techniques will be investigated in
hopes of speeding up Perl.
o CPANPLUS, Inline, and Module::Build will become core
modules.
o The ability to write true lexically scoped pragmas will
be introduced, perhaps via a "pragma" pragma.
o Work will continue on the bytecompiler and byteloader.
o v-strings as they currently exist are scheduled to be
deprecated. The v-less form (1.2.3) will become a
"version object" when used with "use", "require", and
$VERSION. $^V will also be a "version object" so the
printf("%vd",...) construct will no longer be needed.
The v-ful version (v1.2.3) will become obsolete. The
equivalence of strings and v-strings (e.g. that
currently 5.8.0 is equal to "\5\8\0") will go away.
There may be no deprecation warning for v-strings,
though: it is quite hard to detect when v-strings are
being used safely, and when they are not.
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
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.
You can browse and search the Perl 5 bugs at
http://bugs.perl.org/.
ATTRIBUTES
See attributes(5) for descriptions of the following
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attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | runtime/perl-512 |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
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.
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://www.cpan.org/src/5.0/perl-5.12.5.tar.bz2
Further information about this software can be found on the
open source community website at http://www.perl.org/.
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