Document that there are bugs with EBCDIC and regexes

[perl5.git] / pod / perl583delta.pod

=head1 NAME

perl583delta - what is new for perl v5.8.3

=head1 DESCRIPTION

This document describes differences between the 5.8.2 release and
the 5.8.3 release.

If you are upgrading from an earlier release such as 5.6.1, first read
the L<perl58delta>, which describes differences between 5.6.0 and
5.8.0, and the L<perl581delta> and L<perl582delta>, which describe differences
between 5.8.0, 5.8.1 and 5.8.2

=head1 Incompatible Changes

There are no changes incompatible with 5.8.2.

=head1 Core Enhancements

A C<SCALAR> method is now available for tied hashes. This is called when
a tied hash is used in scalar context, such as

    if (%tied_hash) {
	...
    }


The old behaviour was that %tied_hash would return whatever would have been
returned for that hash before the hash was tied (so usually 0). The new
behaviour in the absence of a SCALAR method is to return TRUE if in the
middle of an C<each> iteration, and otherwise call FIRSTKEY to check if the
hash is empty (making sure that a subsequent C<each> will also begin by
calling FIRSTKEY). Please see L<perltie/SCALAR> for the full details and
caveats.

=head1 Modules and Pragmata

=over 4

=item CGI

=item Cwd

=item Digest

=item Digest::MD5

=item Encode

=item File::Spec

=item FindBin

A function C<again> is provided to resolve problems where modules in different
directories wish to use FindBin.

=item List::Util

You can now weaken references to read only values.

=item Math::BigInt

=item PodParser

=item Pod::Perldoc

=item POSIX

=item Unicode::Collate

=item Unicode::Normalize

=item Test::Harness

=item threads::shared

C<cond_wait> has a new two argument form. C<cond_timedwait> has been added.

=back

=head1 Utility Changes

C<find2perl> now assumes C<-print> as a default action. Previously, it
needed to be specified explicitly.

A new utility, C<prove>, makes it easy to run an individual regression test
at the command line. C<prove> is part of Test::Harness, which users of earlier
Perl versions can install from CPAN.

=head1 New Documentation

The documentation has been revised in places to produce more standard manpages.

The documentation for the special code blocks (BEGIN, CHECK, INIT, END)
has been improved.

=head1 Installation and Configuration Improvements

Perl now builds on OpenVMS I64

=head1 Selected Bug Fixes

Using substr() on a UTF8 string could cause subsequent accesses on that
string to return garbage. This was due to incorrect UTF8 offsets being
cached, and is now fixed.

join() could return garbage when the same join() statement was used to
process 8 bit data having earlier processed UTF8 data, due to the flags
on that statement's temporary workspace not being reset correctly. This
is now fixed.

C<$a .. $b> will now work as expected when either $a or $b is C<undef>

Using Unicode keys with tied hashes should now work correctly.

Reading $^E now preserves $!. Previously, the C code implementing $^E
did not preserve C<errno>, so reading $^E could cause C<errno> and therefore
C<$!> to change unexpectedly.

Reentrant functions will (once more) work with C++. 5.8.2 introduced a bugfix
which accidentally broke the compilation of Perl extensions written in C++

=head1 New or Changed Diagnostics

The fatal error "DESTROY created new reference to dead object" is now
documented in L<perldiag>.

=head1 Changed Internals

The hash code has been refactored to reduce source duplication. The
external interface is unchanged, and aside from the bug fixes described
above, there should be no change in behaviour.

C<hv_clear_placeholders> is now part of the perl API

Some C macros have been tidied. In particular macros which create temporary
local variables now name these variables more defensively, which should
avoid bugs where names clash.

<signal.h> is now always included.

=head1 Configuration and Building

C<Configure> now invokes callbacks regardless of the value of the variable
they are called for. Previously callbacks were only invoked in the
C<case $variable $define)> branch. This change should only affect platform
maintainers writing configuration hints files.

=head1 Platform Specific Problems

The regression test ext/threads/shared/t/wait.t fails on early RedHat 9
and HP-UX 10.20 due to bugs in their threading implementations.
RedHat users should see https://rhn.redhat.com/errata/RHBA-2003-136.html
and consider upgrading their glibc.

=head1 Known Problems

Detached threads aren't supported on Windows yet, as they may lead to 
memory access violation problems.

There is a known race condition opening scripts in C<suidperl>. C<suidperl>
is neither built nor installed by default, and has been deprecated since
perl 5.8.0. You are advised to replace use of suidperl with tools such
as sudo ( http://www.courtesan.com/sudo/ )

We have a backlog of unresolved bugs. Dealing with bugs and bug reports
is unglamorous work; not something ideally suited to volunteer labour,
but that is all that we have.

The perl5 development team are implementing changes to help address this
problem, which should go live in early 2004.

=head1 Future Directions

Code freeze for the next maintenance release (5.8.4) is on March 31st 2004,
with release expected by mid April. Similarly 5.8.5's freeze will be at
the end of June, with release by mid July.

=head1 Obituary

Iain 'Spoon' Truskett, Perl hacker, author of L<perlreref> and
contributor to CPAN, died suddenly on 29th December 2003, aged 24.
He will be missed.

=head1 Reporting Bugs

If you find what you think is a bug, you might check the articles
recently posted to the comp.lang.perl.misc newsgroup and the perl
bug database at http://bugs.perl.org.  There may also be
information at http://www.perl.org, the Perl Home Page.

If you believe you have an unreported bug, please run the B<perlbug>
program included with your release.  Be sure to trim your bug down
to a tiny but sufficient test case.  Your bug report, along with the
output of C<perl -V>, will be sent off to perlbug@perl.org to be
analysed by the Perl porting team.  You can browse and search
the Perl 5 bugs at http://bugs.perl.org/

=head1 SEE ALSO

The F<Changes> file for exhaustive details on what changed.

The F<INSTALL> file for how to build Perl.

The F<README> file for general stuff.

The F<Artistic> and F<Copying> files for copyright information.

=cut