perl56delta.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.

The class method C<display_format> and the corresponding object method
C<display_format>, in addition to accepting just one argument, now can
also accept a parameter hash.  Recognized keys of a parameter hash are
C<"style">, which corresponds to the old one parameter case, and two
new parameters: C<"format">, which is a printf()-style format string
(defaults usually to C<"%.15g">, you can revert to the default by
setting the format string to C<undef>) used for both parts of a
complex number, and C<"polar_pretty_print"> (defaults to true),
which controls whether an attempt is made to try to recognize small
multiples and rationals of pi (2pi, pi/2) at the argument (angle) of a
polar complex number.

The potentially disruptive change is that in list context both methods
now I<return the parameter hash>, instead of only the value of the
C<"style"> parameter.

=item Math::Trig

A little bit of radial trigonometry (cylindrical and spherical),
radial coordinate conversions, and the great circle distance were added.

=item Pod::Parser, Pod::InputObjects

Pod::Parser is a base class for parsing and selecting sections of
pod documentation from an input stream.  This module takes care of
identifying pod paragraphs and commands in the input and hands off the
parsed paragraphs and commands to user-defined methods which are free
to interpret or translate them as they see fit.

Pod::InputObjects defines some input objects needed by Pod::Parser, and
for advanced users of Pod::Parser that need more about a command besides
its name and text.

As of release 5.6.0 of Perl, Pod::Parser is now the officially sanctioned
"base parser code" recommended for use by all pod2xxx translators.
Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted
to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already
underway.  For any questions or comments about pod parsing and translating
issues and utilities, please use the [e-mail] mailing list.

For further information, please see L<Pod::Parser> and L<Pod::InputObjects>.

=item Pod::Checker, podchecker

This utility checks pod files for correct syntax, according to
L<perlpod>.  Obvious errors are flagged as such, while warnings are
printed for mistakes that can be handled gracefully.  The checklist is
not complete yet.  See L<Pod::Checker>.

=item Pod::ParseUtils, Pod::Find

These modules provide a set of gizmos that are useful mainly for pod
translators.  L<Pod::Find|Pod::Find> traverses directory structures and
returns found pod files, along with their canonical names (like
C<File::Spec::Unix>).  L<Pod::ParseUtils|Pod::ParseUtils> contains
B<Pod::List> (useful for storing pod list information), B<Pod::Hyperlink>
(for parsing the contents of C<LE<lt>E<gt>> sequences) and B<Pod::Cache>
(for caching information about pod files, e.g., link nodes).

=item Pod::Select, podselect

Pod::Select is a subclass of Pod::Parser which provides a function
named "podselect()" to filter out user-specified sections of raw pod
documentation from an input stream. podselect is a script that provides
access to Pod::Select from other scripts to be used as a filter.
See L<Pod::Select>.

=item Pod::Usage, pod2usage

Pod::Usage provides the function "pod2usage()" to print usage messages for
a Perl script based on its embedded pod documentation.  The pod2usage()
function is generally useful to all script authors since it lets them
write and maintain a single source (the pods) for documentation, thus
removing the need to create and maintain redundant usage message text
consisting of information already in the pods.

There is also a pod2usage script which can be used from other kinds of
scripts to print usage messages from pods (even for non-Perl scripts
with pods embedded in comments).

For details and examples, please see L<Pod::Usage>.

=item Pod::Text and Pod::Man

Pod::Text has been rewritten to use Pod::Parser.  While pod2text() is
still available for backwards compatibility, the module now has a new
preferred interface.  See L<Pod::Text> for the details.  The new Pod::Text
module is easily subclassed for tweaks to the output, and two such
subclasses (Pod::Text::Termcap for man-page-style bold and underlining
using termcap information, and Pod::Text::Color for markup with ANSI color
sequences) are now standard.

pod2man has been turned into a module, Pod::Man, which also uses
Pod::Parser.  In the process, several outstanding bugs related to quotes
in section headers, quoting of code escapes, and nested lists have been
fixed.  pod2man is now a wrapper script around this module.

=item SDBM_File

An EXISTS method has been added to this module (and sdbm_exists() has
been added to the underlying sdbm library), so one can now call exists
on an SDBM_File tied hash and get the correct result, rather than a
runtime error.

A bug that may have caused data loss when more than one disk block
happens to be read from the database in a single FETCH() has been
fixed.

=item Sys::Syslog

Sys::Syslog now uses XSUBs to access facilities from syslog.h so it
no longer requires syslog.ph to exist. 

=item Sys::Hostname

Sys::Hostname now uses XSUBs to call the C library's gethostname() or
uname() if they exist.

=item Term::ANSIColor

Term::ANSIColor is a very simple module to provide easy and readable
access to the ANSI color and highlighting escape sequences, supported by
most ANSI terminal emulators.  It is now included standard.

=item Time::Local

The timelocal() and timegm() functions used to silently return bogus
results when the date fell outside the machine's integer range.  They
now consistently croak() if the date falls in an unsupported range.

=item Win32

The error return value in list context has been changed for all functions
that return a list of values.  Previously these functions returned a list
with a single element C<undef> if an error occurred.  Now these functions
return the empty list in these situations.  This applies to the following
functions:

    Win32::FsType
    Win32::GetOSVersion

The remaining functions are unchanged and continue to return C<undef> on
error even in list context.

The Win32::SetLastError(ERROR) function has been added as a complement
to the Win32::GetLastError() function.

The new Win32::GetFullPathName(FILENAME) returns the full absolute
pathname for FILENAME in scalar context.  In list context it returns
a two-element list containing the fully qualified directory name and
the filename.  See L<Win32>.

=item XSLoader

The XSLoader extension is a simpler alternative to DynaLoader.
See L<XSLoader>.

=item DBM Filters

A new feature called "DBM Filters" has been added to all the
DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File.
DBM Filters add four new methods to each DBM module:

    filter_store_key
    filter_store_value
    filter_fetch_key
    filter_fetch_value

These can be used to filter key-value pairs before the pairs are
written to the database or just after they are read from the database.
See L<perldbmfilter> for further information.

=back

=head2 Pragmata

C<use attrs> is now obsolete, and is only provided for
backward-compatibility.  It's been replaced by the C<sub : attributes>
syntax.  See L<perlsub/"Subroutine Attributes"> and L<attributes>.

Lexical warnings pragma, C<use warnings;>, to control optional warnings.
See L<perllexwarn>.

C<use filetest> to control the behaviour of filetests (C<-r> C<-w>
...).  Currently only one subpragma implemented, "use filetest
'access';", that uses access(2) or equivalent to check permissions
instead of using stat(2) as usual.  This matters in filesystems
where there are ACLs (access control lists): the stat(2) might lie,
but access(2) knows better.

The C<open> pragma can be used to specify default disciplines for
handle constructors (e.g. open()) and for qx//.  The two
pseudo-disciplines C<:raw> and C<:crlf> are currently supported on
DOS-derivative platforms (i.e. where binmode is not a no-op).
See also L</"binmode() can be used to set :crlf and :raw modes">.

=head1 Utility Changes

=head2 dprofpp

C<dprofpp> is used to display profile data generated using C<Devel::DProf>.
See L<dprofpp>.

=head2 find2perl

The C<find2perl> utility now uses the enhanced features of the File::Find
module.  The -depth and -follow options are supported.  Pod documentation
is also included in the script.

=head2 h2xs

The C<h2xs> tool can now work in conjunction with C<C::Scan> (available
from CPAN) to automatically parse real-life header files.  The C<-M>,
C<-a>, C<-k>, and C<-o> options are new.

=head2 perlcc

C<perlcc> now supports the C and Bytecode backends.  By default,
it generates output from the simple C backend rather than the
optimized C backend.

Support for non-Unix platforms has been improved.

=head2 perldoc

C<perldoc> has been reworked to avoid possible security holes.
It will not by default let itself be run as the superuser, but you
may still use the B<-U> switch to try to make it drop privileges
first.

=head2 The Perl Debugger

Many bug fixes and enhancements were added to F<perl5db.pl>, the
Perl debugger.  The help documentation was rearranged.  New commands
include C<< < ? >>, C<< > ? >>, and C<< { ? >> to list out current
actions, C<man I<docpage>> to run your doc viewer on some perl
docset, and support for quoted options.  The help information was
rearranged, and should be viewable once again if you're using B<less>
as your pager.  A serious security hole was plugged--you should
immediately remove all older versions of the Perl debugger as
installed in previous releases, all the way back to perl3, from
your system to avoid being bitten by this.

=head1 Improved Documentation

Many of the platform-specific README files are now part of the perl
installation.  See L<perl> for the complete list.

=over 4

=item perlapi.pod

The official list of public Perl API functions.

=item perlboot.pod

A tutorial for beginners on object-oriented Perl.

=item perlcompile.pod

An introduction to using the Perl Compiler suite.

=item perldbmfilter.pod

A howto document on using the DBM filter facility.

=item perldebug.pod

All material unrelated to running the Perl debugger, plus all
low-level guts-like details that risked crushing the casual user
of the debugger, have been relocated from the old manpage to the
next entry below.

=item perldebguts.pod

This new manpage contains excessively low-level material not related
to the Perl debugger, but slightly related to debugging Perl itself.
It also contains some arcane internal details of how the debugging
process works that may only be of interest to developers of Perl
debuggers.

=item perlfork.pod

Notes on the fork() emulation currently available for the Windows platform.

=item perlfilter.pod

An introduction to writing Perl source filters.

=item perlhack.pod

Some guidelines for hacking the Perl source code.

=item perlintern.pod

A list of internal functions in the Perl source code.
(List is currently empty.)

=item perllexwarn.pod

Introduction and reference information about lexically scoped
warning categories.

=item perlnumber.pod

Detailed information about numbers as they are represented in Perl.

=item perlopentut.pod

A tutorial on using open() effectively.

=item perlreftut.pod

A tutorial that introduces the essentials of references.

=item perltootc.pod

A tutorial on managing class data for object modules.

=item perltodo.pod

Discussion of the most often wanted features that may someday be
supported in Perl.

=item perlunicode.pod

An introduction to Unicode support features in Perl.

=back

=head1 Performance enhancements

=head2 Simple sort() using { $a <=> $b } and the like are optimized

Many common sort() operations using a simple inlined block are now
optimized for faster performance.

=head2 Optimized assignments to lexical variables

Certain operations in the RHS of assignment statements have been
optimized to directly set the lexical variable on the LHS,
eliminating redundant copying overheads.

=head2 Faster subroutine calls

Minor changes in how subroutine calls are handled internally
provide marginal improvements in performance.

=head2 delete(), each(), values() and hash iteration are faster

The hash values returned by delete(), each(), values() and hashes in a
list context are the actual values in the hash, instead of copies.
This results in significantly better performance, because it eliminates
needless copying in most situations.

=head1 Installation and Configuration Improvements

=head2 -Dusethreads means something different

The -Dusethreads flag now enables the experimental interpreter-based thread
support by default.  To get the flavor of experimental threads that was in
5.005 instead, you need to run Configure with "-Dusethreads -Duse5005threads".

As of v5.6.0, interpreter-threads support is still lacking a way to
create new threads from Perl (i.e., C<use Thread;> will not work with