perlbot.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 "PERLBOT 1"
.TH PERLBOT 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.
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.SH "NAME"
perlbot \- Bag'o Object Tricks (the BOT)
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The following collection of tricks and hints is intended to whet curious
appetites about such things as the use of instance variables and the
mechanics of object and class relationships.  The reader is encouraged to
consult relevant textbooks for discussion of Object Oriented definitions and
methodology.  This is not intended as a tutorial for object-oriented
programming or as a comprehensive guide to Perl's object oriented features,
nor should it be construed as a style guide.  If you're looking for tutorials,
be sure to read perlboot, perltoot, and perltooc.
.PP
The Perl motto still holds:  There's more than one way to do it.
.SH "OO SCALING TIPS"
.IX Header "OO SCALING TIPS"
.IP "1." 5
Do not attempt to verify the type of \f(CW$self\fR.  That'll break if the class is
inherited, when the type of \f(CW$self\fR is valid but its package isn't what you
expect.  See rule 5.
.IP "2." 5
If an object-oriented (\s-1OO\s0) or indirect-object (\s-1IO\s0) syntax was used, then the
object is probably the correct type and there's no need to become paranoid
about it.  Perl isn't a paranoid language anyway.  If people subvert the \s-1OO\s0
or \s-1IO\s0 syntax then they probably know what they're doing and you should let
them do it.  See rule 1.
.IP "3." 5
Use the two-argument form of \fIbless()\fR.  Let a subclass use your constructor.
See \*(L"\s-1INHERITING\s0 A \s-1CONSTRUCTOR\s0\*(R".
.IP "4." 5
The subclass is allowed to know things about its immediate superclass, the
superclass is allowed to know nothing about a subclass.
.IP "5." 5
Don't be trigger happy with inheritance.  A \*(L"using\*(R", \*(L"containing\*(R", or
\&\*(L"delegation\*(R" relationship (some sort of aggregation, at least) is often more
appropriate.  See \*(L"\s-1OBJECT\s0 \s-1RELATIONSHIPS\s0\*(R", \*(L"\s-1USING\s0 \s-1RELATIONSHIP\s0 \s-1WITH\s0 \s-1SDBM\s0\*(R",
and \*(L"\s-1DELEGATION\s0\*(R".
.IP "6." 5
The object is the namespace.  Make package globals accessible via the
object.  This will remove the guess work about the symbol's home package.
See \*(L"\s-1CLASS\s0 \s-1CONTEXT\s0 \s-1AND\s0 \s-1THE\s0 \s-1OBJECT\s0\*(R".
.IP "7." 5
\&\s-1IO\s0 syntax is certainly less noisy, but it is also prone to ambiguities that
can cause difficult-to-find bugs.  Allow people to use the sure-thing \s-1OO\s0
syntax, even if you don't like it.
.IP "8." 5
Do not use function-call syntax on a method.  You're going to be bitten
someday.  Someone might move that method into a superclass and your code
will be broken.  On top of that you're feeding the paranoia in rule 2.
.IP "9." 5
Don't assume you know the home package of a method.  You're making it
difficult for someone to override that method.  See \*(L"\s-1THINKING\s0 \s-1OF\s0 \s-1CODE\s0 \s-1REUSE\s0\*(R".
.SH "INSTANCE VARIABLES"
.IX Header "INSTANCE VARIABLES"
An anonymous array or anonymous hash can be used to hold instance
variables.  Named parameters are also demonstrated.
.PP
.Vb 1
\&        package Foo;
\&
\&        sub new {
\&                my $type = shift;
\&                my %params = @_;
\&                my $self = {};
\&                $self\->{\*(AqHigh\*(Aq} = $params{\*(AqHigh\*(Aq};
\&                $self\->{\*(AqLow\*(Aq}  = $params{\*(AqLow\*(Aq};
\&                bless $self, $type;
\&        }
\&
\&
\&        package Bar;
\&
\&        sub new {
\&                my $type = shift;
\&                my %params = @_;
\&                my $self = [];
\&                $self\->[0] = $params{\*(AqLeft\*(Aq};
\&                $self\->[1] = $params{\*(AqRight\*(Aq};
\&                bless $self, $type;
\&        }
\&
\&        package main;
\&
\&        $a = Foo\->new( \*(AqHigh\*(Aq => 42, \*(AqLow\*(Aq => 11 );
\&        print "High=$a\->{\*(AqHigh\*(Aq}\en";
\&        print "Low=$a\->{\*(AqLow\*(Aq}\en";
\&
\&        $b = Bar\->new( \*(AqLeft\*(Aq => 78, \*(AqRight\*(Aq => 40 );
\&        print "Left=$b\->[0]\en";
\&        print "Right=$b\->[1]\en";
.Ve
.SH "SCALAR INSTANCE VARIABLES"
.IX Header "SCALAR INSTANCE VARIABLES"
An anonymous scalar can be used when only one instance variable is needed.
.PP
.Vb 1
\&        package Foo;
\&
\&        sub new {
\&                my $type = shift;
\&                my $self;
\&                $self = shift;
\&                bless \e$self, $type;
\&        }
\&
\&        package main;
\&
\&        $a = Foo\->new( 42 );
\&        print "a=$$a\en";
.Ve
.SH "INSTANCE VARIABLE INHERITANCE"
.IX Header "INSTANCE VARIABLE INHERITANCE"
This example demonstrates how one might inherit instance variables from a
superclass for inclusion in the new class.  This requires calling the
superclass's constructor and adding one's own instance variables to the new
object.
.PP
.Vb 1
\&        package Bar;
\&
\&        sub new {
\&                my $type = shift;
\&                my $self = {};
\&                $self\->{\*(Aqbuz\*(Aq} = 42;
\&                bless $self, $type;
\&        }
\&
\&        package Foo;
\&        @ISA = qw( Bar );
\&
\&        sub new {
\&                my $type = shift;
\&                my $self = Bar\->new;
\&                $self\->{\*(Aqbiz\*(Aq} = 11;
\&                bless $self, $type;
\&        }
\&
\&        package main;
\&
\&        $a = Foo\->new;
\&        print "buz = ", $a\->{\*(Aqbuz\*(Aq}, "\en";
\&        print "biz = ", $a\->{\*(Aqbiz\*(Aq}, "\en";
.Ve
.SH "OBJECT RELATIONSHIPS"
.IX Header "OBJECT RELATIONSHIPS"
The following demonstrates how one might implement \*(L"containing\*(R" and \*(L"using\*(R"
relationships between objects.
.PP
.Vb 1
\&        package Bar;
\&
\&        sub new {
\&                my $type = shift;
\&                my $self = {};
\&                $self\->{\*(Aqbuz\*(Aq} = 42;
\&                bless $self, $type;
\&        }
\&
\&        package Foo;
\&
\&        sub new {
\&                my $type = shift;
\&                my $self = {};
\&                $self\->{\*(AqBar\*(Aq} = Bar\->new;
\&                $self\->{\*(Aqbiz\*(Aq} = 11;
\&                bless $self, $type;
\&        }
\&
\&        package main;
\&
\&        $a = Foo\->new;
\&        print "buz = ", $a\->{\*(AqBar\*(Aq}\->{\*(Aqbuz\*(Aq}, "\en";
\&        print "biz = ", $a\->{\*(Aqbiz\*(Aq}, "\en";
.Ve
.SH "OVERRIDING SUPERCLASS METHODS"
.IX Header "OVERRIDING SUPERCLASS METHODS"
The following example demonstrates how to override a superclass method and
then call the overridden method.  The \fB\s-1SUPER\s0\fR pseudo-class allows the
programmer to call an overridden superclass method without actually knowing
where that method is defined.
.PP
.Vb 2
\&        package Buz;
\&        sub goo { print "here\*(Aqs the goo\en" }
\&
\&        package Bar; @ISA = qw( Buz );
\&        sub google { print "google here\en" }
\&
\&        package Baz;
\&        sub mumble { print "mumbling\en" }