perl571delta.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.

=item *

s2p has been completely rewritten in Perl.  (It is in fact a full
implementation of sed in Perl.)

=item *

xsubpp now supports OUT keyword.

=back

=head1 New Documentation

=head2 perlclib

Internal replacements for standard C library functions.
(Interesting only for extension writers and Perl core hackers.)

=head2 perliol

Internals of PerlIO with layers.

=head2 README.aix

Documentation on compiling Perl on AIX has been added.  AIX has
several different C compilers and getting the right patch level
is essential.  On install README.aix will be installed as L<perlaix>.

=head2 README.bs2000

Documentation on compiling Perl on the POSIX-BC platform (an EBCDIC
mainframe environment) has been added.

This was formerly known as README.posix-bc but the name was considered
to be too confusing (it has nothing to do with the POSIX module or the
POSIX standard).  On install README.bs2000 will be installed as L<perlbs2000>.

=head2 README.macos

In perl 5.7.1 (and in the 5.6.1) the MacPerl sources have been
synchronised with the standard Perl sources.  To compile MacPerl
some additional steps are required, and this file documents those
steps.  On install README.macos will be installed as L<perlmacos>.

=head2 README.mpeix

The README.mpeix has been podified, which means that this information
about compiling and using Perl on the MPE/iX miniframe platform will
be installed as L<perlmpeix>.

=head2 README.solaris

README.solaris has been created and Solaris wisdom from elsewhere
in the Perl documentation has been collected there.  On install
README.solaris will be installed as L<perlsolaris>.

=head2 README.vos

The README.vos has been podified, which means that this information
about compiling and using Perl on the Stratus VOS miniframe platform
will be installed as L<perlvos>.

=head2 Porting/repository.pod

Documentation on how to use the Perl source repository has been added.

=head1 Installation and Configuration Improvements

=over 4

=item *

Because PerlIO is now the default on most platforms, "-perlio" doesn't
get appended to the $Config{archname} (also known as $^O) anymore.
Instead, if you explicitly choose not to use perlio (Configure command
line option -Uuseperlio), you will get "-stdio" appended.

=item *

Another change related to the architecture name is that "-64all"
(-Duse64bitall, or "maximally 64-bit") is appended only if your
pointers are 64 bits wide.  (To be exact, the use64bitall is ignored.)

=item *

APPLLIB_EXP, a less-know configuration-time definition, has been
documented.  It can be used to prepend site-specific directories
to Perl's default search path (@INC), see INSTALL for information.

=item *

Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
has been documented in INSTALL.

=item *

If you are on IRIX or Tru64 platforms, new profiling/debugging options
have been added, see L<perlhack> for more information about pixie and
Third Degree.

=back

=head2 New Or Improved Platforms

For the list of platforms known to support Perl,
see L<perlport/"Supported Platforms">.

=over 4

=item *

AIX dynamic loading should be now better supported.

=item *

After a long pause, AmigaOS has been verified to be happy with Perl.

=item *

EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
have been regained.  Many test suite tests still fail and the
co-existence of Unicode and EBCDIC isn't quite settled, but the
situation is much better than with Perl 5.6.  See L<perlos390>,
L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.

=item *

Building perl with -Duseithreads or -Duse5005threads now works under
HP-UX 10.20 (previously it only worked under 10.30 or later). You will
need a thread library package installed. See README.hpux.

=item *

Mac OS Classic (MacPerl has of course been available since
perl 5.004 but now the source code bases of standard Perl
and MacPerl have been synchronised)

=item *

NCR MP-RAS is now supported.

=item *

NonStop-UX is now supported.

=item *

Amdahl UTS is now supported.

=item *

z/OS (formerly known as OS/390, formerly known as MVS OE) has now
support for dynamic loading.  This is not selected by default,
however, you must specify -Dusedl in the arguments of Configure.

=back

=head2 Generic Improvements

=over 4

=item *

Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
when building the Perl binary.  The only exception to this is SunOS 4.x,
which needs them.

=item *

Some new Configure symbols, useful for extension writers:

=over 8

=item d_cmsghdr

For struct cmsghdr.

=item d_fcntl_can_lock

Whether fcntl() can be used for file locking.

=item d_fsync

=item d_getitimer

=item d_getpagsz

For getpagesize(), though you should prefer POSIX::sysconf(_SC_PAGE_SIZE))

=item d_msghdr_s

For struct msghdr.

=item need_va_copy

Whether one needs to use Perl_va_copy() to copy varargs.

=item d_readv

=item d_recvmsg

=item d_sendmsg

=item sig_size

The number of elements in an array needed to hold all the available signals.

=item d_sockatmark

=item d_strtoq

=item d_u32align

Whether one needs to access character data aligned by U32 sized pointers.

=item d_ualarm

=item d_usleep

=back

=item *

Removed Configure symbols: the PDP-11 memory model settings: huge,
large, medium, models.

=item *

SOCKS support is now much more robust.

=item *

If your file system supports symbolic links you can build Perl outside
of the source directory by

	mkdir perl/build/directory
	cd perl/build/directory
	sh /path/to/perl/source/Configure -Dmksymlinks ...

This will create in 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 perl/build/directory.

=back

=head1 Selected Bug Fixes

Numerous memory leaks and uninitialized memory accesses have been hunted down.
Most importantly anonymous subs used to leak quite a bit.

=over 4

=item *

chop(@list) in list context returned the characters chopped in
reverse order.  This has been reversed to be in the right order.

=item *

The order of DESTROYs has been made more predictable.

=item *

mkdir() now ignores trailing slashes in the directory name,
as mandated by POSIX.

=item *

Attributes (like :shared) didn't work with our().

=item *

The PERL5OPT environment variable (for passing command line arguments
to Perl) didn't work for more than a single group of options.

=item *

The tainting behaviour of sprintf() has been rationalized.  It does
not taint the result of floating point formats anymore, making the
behaviour consistent with that of string interpolation.

=item *

All but the first argument of the IO syswrite() method are now optional.

=item *

Tie::ARRAY SPLICE method was broken.

=item *

vec() now tries to work with characters <= 255 when possible, but it leaves
higher character values in place.  In that case, if vec() was used to modify
the string, it is no longer considered to be utf8-encoded.

=back

=head2 Platform Specific Changes and Fixes

=over 4

=item *

Linux previously had problems related to sockaddrlen when using
accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().

=item *

Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.

=item *

Windows

=over 8

=item *

Borland C++ v5.5 is now a supported compiler that can build Perl.
However, the generated binaries continue to be incompatible with those
generated by the other supported compilers (GCC and Visual C++).

=item *

Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
Other bugs in chdir() and Cwd::cwd() have also been fixed.

=item *

Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.

=item *

HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html

=item *

The makefiles now provide a single switch to bulk-enable all the features
enabled in ActiveState ActivePerl (a popular binary distribution).

=back

=back

=head1 New or Changed Diagnostics

Two new debugging options have been added: if you have compiled your
Perl with debugging, you can use the -DT and -DR options to trace
tokenising and to add reference counts to displaying variables,
respectively.

=over 4

=item *

If an attempt to use a (non-blessed) reference as an array index
is made, a warning is given.

=item *

C<push @a;> and C<unshift @a;> (with no values to push or unshift)
now give a warning.  This may be a problem for generated and eval'ed
code.

=back

=head1 Changed Internals

=over 4

=item *

Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
For the full list of the available APIs see L<perlapi>.

=item *

dTHR and djSP have been obsoleted; the former removed (because it's
a no-op) and the latter replaced with dSP.

=item *

Perl now uses system malloc instead of Perl malloc on all 64-bit
platforms, and even in some not-always-64-bit platforms like AIX,
IRIX, and Solaris.  This change breaks backward compatibility but
Perl's malloc has problems with large address spaces and also the
speed of vendors' malloc is generally better in large address space
machines (Perl's malloc is mostly tuned for space).

=back

=head1 New Tests

Many new tests have been added.  The most notable is probably the
lib/1_compile: it is very notable because running it takes quite a
long time -- it test compiles all the Perl modules in the distribution.
Please be patient.

=head1 Known Problems

Note that unlike other sections in this document (which describe
changes since 5.7.0) this section is cumulative containing known
problems for all the 5.7 releases.

=head2 AIX vac 5.0.0.0 May Produce Buggy Code For Perl

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.

=head2 lib/ftmp-security tests warn 'system possibly insecure'

Don't panic.  Read INSTALL 'make test' section instead.

=head2 lib/io_multihomed Fails In LP64-Configured HP-UX

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).

=head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX

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.

=head2 lib/b test 19

The test fails on various platforms (PA64 and IA64 are known), but the
exact cause is still being investigated.

=head2 Linux With Sfio Fails op/misc Test 48

No known fix.

=head2 sigaction test 13 in VMS

The test is known to fail; whether it's because of VMS of because
of faulty test is not known.

=head2 sprintf tests 129 and 130

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 else than "1" and "-1" when formatting 0.6 and -0.6 using
the printf format "%.0f", most often they produce "0" and "-0".)

=head2  Failure of Thread tests

The subtests 19 and 20 of lib/thr5005.t test 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. (Note that support for 5.005-style threading remains
experimental.)

=head2 Localising a Tied Variable Leaks Memory

    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.

=head2 Self-tying of Arrays and Hashes Is Forbidden

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).

=head2 Building Extensions Can Fail Because Of Largefiles

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.

=head2 The Compiler Suite Is Still Experimental

The compiler suite is slowly getting better but is nowhere near
working order yet.

=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.com/perl/ , 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.

=head1 HISTORY

Written by Jarkko Hietaniemi <F<[e-mail]>>, with many contributions
from The Perl Porters and Perl Users submitting feedback and patches.

Send omissions or corrections to <F<[e-mail]>>.

=cut