perl593delta.pod

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

Salvador Fandi駉 provided improvements to reduce the memory usage of C<sort>
and to speed up some cases.

=head1 Installation and Configuration Improvements

=head2 Compilation improvements

Parallel makes should work properly now, although there may still be problems
if C<make test> is instructed to run in parallel.

Building with Borland's compilers on Win32 should work more smoothly. In
particular Steve Hay has worked to side step many warnings emitted by their
compilers and at least one C compiler internal error.

Perl extensions on Windows now can be statically built into the Perl DLL,
thanks to a work by Vadim Konovalov.

=head2 New Or Improved Platforms

Perl is being ported to Symbian OS. See L<perlsymbian> for more
information.

The VMS port has been improved. See L<perlvms>.

DynaLoader::dl_unload_file() now works on Windows.

Portability of Perl on various recent compilers on Windows has been
improved (Borland C++, Visual C++ 7.0).

=head2 New probes

C<Configure> will now detect C<clearenv> and C<unsetenv>, thanks to a
patch from Alan Burlison. It will also probe for C<futimes> (and use it
internally if available), and whether C<sprintf> correctly returns the
length of the formatted string.

=head2 Module auxiliary files

README files and changelogs for CPAN modules bundled with perl are no
longer installed.

=head1 Selected Bug Fixes

=head2 C<defined $$x>

C<use strict "refs"> was ignoring taking a hard reference in an argument
to defined(), as in :

    use strict "refs";
    my $x = "foo";
    if (defined $$x) {...}

This now correctly produces the run-time error C<Can't use string as a
SCALAR ref while "strict refs" in use>. (However, C<defined @$foo> and
C<defined %$foo> are still allowed. Those constructs are discouraged
anyway.)

=head2 Calling CORE::require()

CORE::require() and CORE::do() were always parsed as require() and do()
when they were overridden. This is now fixed.

=head2 Subscripts of slices

You can now use a non-arrowed form for chained subscripts after a list
slice, like in:

    ({foo => "bar"})[0]{foo}

This used to be a syntax error; a C<< -> >> was required.

=head2 Remove over-optimisation

Perl 5.9.2 introduced a change so that assignments of C<undef> to a
scalar, or of an empty list to an array or a hash, were optimised out. As
this could cause problems when C<goto> jumps were involved, this change
was backed out.

=head2 sprintf() fixes

Using the sprintf() function with some formats could lead to a buffer
overflow in some specific cases. This has been fixed, along with several
other bugs, notably in bounds checking.

In related fixes, it was possible for badly written code that did not follow
the documentation of C<Sys::Syslog> to have formatting vulnerabilities.
C<Sys::Syslog> has been changed to protect people from poor quality third
party code.

=head2 no warnings 'category' works correctly with -w

Previously when running with warnings enabled globally via C<-w>, selective
disabling of specific warning categories would actually turn off all warnings.
This is now fixed; now C<no warnings 'io';> will only turn off warnings in the
C<io> class. Previously it would erroneously turn off all warnings.

=head2 Smaller fixes

=over 4

=item *

C<FindBin> now works better with directories where access rights are more
restrictive than usual.

=item *

Several memory leaks in ithreads were closed. Also, ithreads were made
less memory-intensive.

=item *

Trailing spaces are now trimmed from C<$!> and C<$^E>.

=item *

Operations that require perl to read a process' list of groups, such as reads
of C<$(> and C<$)>, now dynamically allocate memory rather than using a
fixed sized array. The fixed size array could cause C stack exhaustion on
systems configured to use large numbers of groups.

=item *

C<PerlIO::scalar> now works better with non-default C<$/> settings.

=item *

The C<x> repetition operator is now able to operate on C<qw//> lists. This
used to raise a syntax error.

=item *

The debugger now traces correctly execution in eval("")uated code that
contains #line directives.

=item *

The value of the C<open> pragma is no longer ignored for three-argument
opens.

=item *

Perl will now use the C library calls C<unsetenv> and C<clearenv> if present
to delete keys from C<%ENV> and delete C<%ENV> entirely, thanks to a patch
from Alan Burlison.

=back

=head2 More Unicode Fixes

=over 4

=item *

chr() on a negative value now gives C<\x{FFFD}>, the Unicode replacement
character, unless when the C<bytes> pragma is in effect, where the low
eight bytes of the value are used.

=item *

Some case insensitive matches between UTF-8 encoded data and 8 bit regexps,
and vice versa, could give malformed character warnings. These have been
fixed by Dave Mitchell and Yves Orton.

=item *

C<lcfirst> and C<ucfirst> could corrupt the string for certain cases where
the length UTF-8 encoding of the string in lower case, upper case or title
case differed. This was fixed by Nicholas Clark.

=back

=head1 New or Changed Diagnostics

=head2 Attempt to set length of freed array

This is a new warning, produced in situations like the following one:

    $r = do {my @a; \$#a};
    $$r = 503;

=head2 Non-string passed as bitmask

This is a new warning, produced when number has been passed as a argument to
select(), instead of a bitmask.

    # Wrong, will now warn
    $rin = fileno(STDIN);
    ($nfound,$timeleft) = select($rout=$rin, undef, undef, $timeout);
    
    # Should be
    $rin = '';
    vec($rin,fileno(STDIN),1) = 1;
    ($nfound,$timeleft) = select($rout=$rin, undef, undef, $timeout);

=head2 Search pattern not terminated or ternary operator parsed as search pattern

This syntax error indicates that the lexer couldn't find the final
delimiter of a C<?PATTERN?> construct. Mentioning the ternary operator in
this error message makes syntax diagnostic easier.

=head2 "%s" variable %s masks earlier declaration

This warning is now emitted in more consistent cases; in short, when one
of the declarations involved is a C<my> variable:

    my $x;   my $x;	# warns
    my $x;  our $x;	# warns
    our $x;  my $x;	# warns

On the other hand, the following:

    our $x; our $x;

now gives a C<"our" variable %s redeclared> warning.

=head2 readdir()/closedir()/etc. attempted on invalid dirhandle

These new warnings are now emitted when a dirhandle is used but is
either closed or not really a dirhandle.

=head1 Changed Internals

In general, the source code of perl has been refactored, tied up, and
optimized in many places. Also, memory management and allocation has been
improved in a couple of points.

Andy Lester supplied many improvements to determine which function
parameters and local variables could actually be declared C<const> to the C
compiler. Steve Peters provided new C<*_set> macros and reworked the core to
use these rather than assigning to macros in LVALUE context.

Dave Mitchell improved the lexer debugging output under C<-DT>.

A new file, F<mathoms.c>, has been added. It contains functions that are
no longer used in the perl core, but that remain available for binary or
source compatibility reasons. However, those functions will not be
compiled in if you add C<-DNO_MATHOMS> in the compiler flags.

The C<AvFLAGS> macro has been removed.

The C<av_*()> functions, used to manipulate arrays, no longer accept null
C<AV*> parameters.

=head2 B:: modules inheritance changed

The inheritance hierarchy of C<B::> modules has changed; C<B::NV> now
inherits from C<B::SV> (it used to inherit from C<B::IV>).

=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 [e-mail] to be
analysed by the Perl porting team.

=head1 SEE ALSO

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

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

The F<README> file for general stuff.

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

=cut