perl581delta - what is new for perl v5.8.1
This document describes differences between the 5.8.0
release and the 5.8.1 release.
If you are upgrading from an earlier release such as
5.6.1, first read the perl58delta, which describes differences
between 5.6.0 and 5.8.0.
In case you are wondering about 5.6.1, it was bug-fix-wise
rather identical to the development release 5.7.1. Confused?
This timeline hopefully helps a bit: it lists the
new major releases, their maintenance releases, and the
development releases.
New Maintenance Development
5.6.0 2000-Mar-22
5.7.0 2000-Sep-02
5.6.1 2001-Apr-08
5.7.1 2001-Apr-09
5.7.2 2001-Jul-13
5.7.3 2002-Mar-05
5.8.0 2002-Jul-18
5.8.1 2003-Sep-25
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, 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 [Toc] [Back]
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 [Toc] [Back]
"=>"
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
restores 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, datadependent
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
Perl 5.8.1 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".
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 [Toc] [Back]
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 introduces 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.
In completely unrelated news, you can now use safe signals
with POSIX::SigAction. See "POSIX::SigAction" in POSIX.
Tied Arrays with Negative Array Indices [Toc] [Back]
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 [Toc] [Back]
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.
Deprecation Warnings [Toc] [Back]
There is one new feature deprecation. Perl 5.8.0 forgot
to add some deprecation warnings, these warnings have now
been added. Finally, a reminder of an impending feature
removal.
(Reminder) Pseudo-hashes are deprecated (really)
Pseudo-hashes were deprecated in Perl 5.8.0 and will be
removed in Perl 5.10.0, see perl58delta for details. Each
attempt to access pseudo-hashes will trigger the warning
"Pseudo-hashes are deprecated". If you really want to
continue using pseudo-hashes but not to see the deprecation
warnings, use:
no warnings 'deprecated';
Or you can continue to use the fields pragma, but please
don't expect the data structures to be pseudohashes any
more.
(Reminder) 5.005-style threads are deprecated (really)
5.005-style threads (activated by "use Thread;") were deprecated
in Perl 5.8.0 and will be removed after Perl 5.8,
see perl58delta for details. Each 5.005-style thread creation
will trigger the warning "5.005 threads are deprecated".
If you really want to continue using the 5.005
threads but not to see the deprecation warnings, use:
no warnings 'deprecated';
(Reminder) The $* variable is deprecated (really)
The $* variable controlling multi-line matching has been
deprecated and will be removed after 5.8. The variable
has been deprecated for a long time, and a deprecation
warning "Use of $* is deprecated" is given, now the variable
will just finally be removed. The functionality has
been supplanted by the "/s" and "/m" modifiers on pattern
matching. If you really want to continue using the
$*-variable but not to see the deprecation warnings, use:
no warnings 'deprecated';
Miscellaneous Enhancements [Toc] [Back]
"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).
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).
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:
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
Now returns extra information.
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 featureful.
"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.)
perl573delta has been added to list the differences
between the (now quite obsolete) development releases
5.7.2 and 5.7.3.
perl58delta has been added: it is the perldelta of 5.8.0,
detailing the differences between 5.6.0 and 5.8.0.
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 [Toc] [Back] 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.
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 [Toc] [Back]
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 usercompiled
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 care-
ful).
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.
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.
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.
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 [Toc] [Back]
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 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 [Toc] [Back] 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.
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
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 "Pseudo-hashes are deprecated"
This warning should have been already in 5.8.0, since they
are.
New "read() on %s filehandle %s"
You cannot read() (or sysread()) from a closed or unopened
filehandle.
New "5.005 threads are deprecated"
This warning should have been already in 5.8.0, since they
are.
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.
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 uptodate 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.
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. In Perl 5.8.0 there were about 69000 separate tests in
about 700 test files, in Perl 5.8.1 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.
The hash randomisation mentioned in "Incompatible Changes"
is definitely problematic: it will wake dormant bugs and
shake out bad assumptions.
If you want to use mod_perl 2.x with Perl 5.8.1, you will
need mod_perl-1.99_10 or higher. Earlier versions of
mod_perl 2.x do not work with the randomised hashes.
(mod_perl 1.x works fine.) You will also need
Apache::Test 1.04 or higher.
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 [Toc] [Back]
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 [Toc] [Back] 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.
Cygwin 1.5 problems [Toc] [Back]
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 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 reintroduced
in a future release. Until then, the use of
sysopen(), sysread() and syswrite() is not supported for
"text" mode operations.
The following things might happen in future. The first
publicly available releases having these characteristics
will be the developer releases Perl 5.9.x, culminating in
the Perl 5.10.0 release. These are our best guesses at
the moment: we reserve the right to rethink.
o PerlIO will become The Default. Currently (in Perl
5.8.x) the stdio library is still used if Perl thinks
it can use certain tricks to make stdio go really
fast. For future releases our goal is to make PerlIO
go even faster.
o A new feature called assertions will be available.
This means that one can have code called assertions
sprinkled in the code: usually they are optimised
away, but they can be enabled with the "-A" option.
o A new operator "//" (defined-or) will be available.
This means that one will be able to say
$a // $b
instead of
defined $a ? $a : $b
and
$c //= $d;
instead of
$c = $d unless defined $c;
The operator will have the same precedence and associativity
as "||". A source code patch against the
Perl 5.8.1 sources will be available in CPAN as
authors/id/H/HM/HMBRAND/dor-5.8.1.diff.
o "unpack()" will default to unpacking the $_.
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.
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 "58 ") 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.
o 5.005 Threads Will Be Removed
o The $* Variable Will Be Removed (it was deprecated a
long time ago)
o Pseudohashes Will Be Removed
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 [email protected] to be analysed by the Perl
porting team. You can browse and search the Perl 5 bugs
at http://bugs.perl.org/
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.
perl v5.8.5 2002-11-06 21 [ Back ] |
