perlfaq3.1

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.

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.\" ========================================================================
.\"
.IX Title "PERLFAQ3 1"
.TH PERLFAQ3 1 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
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.SH "NAME"
perlfaq3 \- Programming Tools ($Revision: 10127 $)
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This section of the \s-1FAQ\s0 answers questions related to programmer tools
and programming support.
.Sh "How do I do (anything)?"
.IX Subsection "How do I do (anything)?"
Have you looked at \s-1CPAN\s0 (see perlfaq2)?  The chances are that
someone has already written a module that can solve your problem.
Have you read the appropriate manpages?  Here's a brief index:
.PP
.Vb 12
\&        Basics          perldata, perlvar, perlsyn, perlop, perlsub
\&        Execution       perlrun, perldebug
\&        Functions       perlfunc
\&        Objects         perlref, perlmod, perlobj, perltie
\&        Data Structures perlref, perllol, perldsc
\&        Modules         perlmod, perlmodlib, perlsub
\&        Regexes         perlre, perlfunc, perlop, perllocale
\&        Moving to perl5 perltrap, perl
\&        Linking w/C     perlxstut, perlxs, perlcall, perlguts, perlembed
\&        Various         http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz
\&                        (not a man\-page but still useful, a collection
\&                         of various essays on Perl techniques)
.Ve
.PP
A crude table of contents for the Perl manpage set is found in perltoc.
.Sh "How can I use Perl interactively?"
.IX Subsection "How can I use Perl interactively?"
The typical approach uses the Perl debugger, described in the
\&\fIperldebug\fR\|(1) manpage, on an \*(L"empty\*(R" program, like this:
.PP
.Vb 1
\&    perl \-de 42
.Ve
.PP
Now just type in any legal Perl code, and it will be immediately
evaluated.  You can also examine the symbol table, get stack
backtraces, check variable values, set breakpoints, and other
operations typically found in symbolic debuggers.
.Sh "Is there a Perl shell?"
.IX Subsection "Is there a Perl shell?"
The psh (Perl sh) is currently at version 1.8. The Perl Shell is a shell
that combines the interactive nature of a Unix shell with the power of
Perl. The goal is a full featured shell that behaves as expected for
normal shell activity and uses Perl syntax and functionality for
control-flow statements and other things. You can get psh at
http://sourceforge.net/projects/psh/ .
.PP
Zoidberg is a similar project and provides a shell written in perl,
configured in perl and operated in perl. It is intended as a login shell
and development environment. It can be found at http://zoidberg.sf.net/
or your local \s-1CPAN\s0 mirror.
.PP
The Shell.pm module (distributed with Perl) makes Perl try commands
which aren't part of the Perl language as shell commands.  perlsh from
the source distribution is simplistic and uninteresting, but may still
be what you want.
.Sh "How do I find which modules are installed on my system?"
.IX Subsection "How do I find which modules are installed on my system?"
You can use the ExtUtils::Installed module to show all installed
distributions, although it can take awhile to do its magic.  The
standard library which comes with Perl just shows up as \*(L"Perl\*(R" (although
you can get those with Module::CoreList).
.PP
.Vb 1
\&        use ExtUtils::Installed;
\&
\&        my $inst    = ExtUtils::Installed\->new();
\&        my @modules = $inst\->modules();
.Ve
.PP
If you want a list of all of the Perl module filenames, you
can use File::Find::Rule.
.PP
.Vb 1
\&        use File::Find::Rule;
\&
\&        my @files = File::Find::Rule\->file()\->name( \*(Aq*.pm\*(Aq )\->in( @INC );
.Ve
.PP
If you do not have that module, you can do the same thing
with File::Find which is part of the standard library.
.PP
.Vb 2
\&    use File::Find;
\&    my @files;
\&
\&    find(
\&      sub {
\&        push @files, $File::Find::name
\&                if \-f $File::Find::name && /\e.pm$/
\&        },
\&
\&      @INC
\&      );
\&
\&        print join "\en", @files;
.Ve
.PP
If you simply need to quickly check to see if a module is
available, you can check for its documentation.  If you can
read the documentation the module is most likely installed.
If you cannot read the documentation, the module might not
have any (in rare cases).
.PP
.Vb 1
\&        prompt% perldoc Module::Name
.Ve
.PP
You can also try to include the module in a one-liner to see if
perl finds it.
.PP
.Vb 1
\&        perl \-MModule::Name \-e1
.Ve
.Sh "How do I debug my Perl programs?"
.IX Subsection "How do I debug my Perl programs?"
(contributed by brian d foy)
.PP
Before you do anything else, you can help yourself by ensuring that
you let Perl tell you about problem areas in your code. By turning
on warnings and strictures, you can head off many problems before
they get too big. You can find out more about these in strict
and warnings.
.PP
.Vb 3
\&        #!/usr/bin/perl
\&        use strict;
\&        use warnings;
.Ve
.PP
Beyond that, the simplest debugger is the \f(CW\*(C`print\*(C'\fR function. Use it
to look at values as you run your program:
.PP
.Vb 1
\&        print STDERR "The value is [$value]\en";
.Ve
.PP
The \f(CW\*(C`Data::Dumper\*(C'\fR module can pretty-print Perl data structures:
.PP
.Vb 2
\&        use Data::Dumper qw( Dumper );
\&        print STDERR "The hash is " . Dumper( \e%hash ) . "\en";
.Ve
.PP
Perl comes with an interactive debugger, which you can start with the
\&\f(CW\*(C`\-d\*(C'\fR switch. It's fully explained in perldebug.
.PP
If you'd like a graphical user interface and you have Tk, you can use