object::accessor.3

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.

respective input validators. The validators can be anything that
\&\f(CW\*(C`Params::Check\*(C'\fR's \f(CW\*(C`allow\*(C'\fR function accepts. Please see its manpage
for details.
.PP
For example:
.PP
.Vb 5
\&    $object\->mk_accessors( {
\&        foo     => qr/^\ed+$/,       # digits only
\&        bar     => [0,1],           # booleans
\&        zot     => \e&my_sub         # a custom verification sub
\&    } );
.Ve
.PP
Returns true on success, false on failure.
.PP
Accessors that are called on an object, that do not exist return
\&\f(CW\*(C`undef\*(C'\fR by default, but you can make this a fatal error by setting the
global variable \f(CW$FATAL\fR to true. See the section on \f(CW\*(C`GLOBAL
VARIABLES\*(C'\fR for details.
.PP
Note that you can bind the values of attributes to a scope. This allows
you to \f(CW\*(C`temporarily\*(C'\fR change a value of an attribute, and have it's 
original value restored up on the end of it's bound variable's scope;
.PP
For example, in this snippet of code, the attribute \f(CW\*(C`foo\*(C'\fR will 
temporarily be set to \f(CW2\fR, until the end of the scope of \f(CW$x\fR, at 
which point the original value of \f(CW1\fR will be restored.
.PP
.Vb 1
\&    my $obj = Object::Accessor\->new;
\&    
\&    $obj\->mk_accessors(\*(Aqfoo\*(Aq);
\&    $obj\->foo( 1 );
\&    print $obj\->foo;                # will print 1
\&
\&    ### bind the scope of the value of attribute \*(Aqfoo\*(Aq
\&    ### to the scope of \*(Aq$x\*(Aq \-\- when $x goes out of 
\&    ### scope, \*(Aqfoo\*(Aq previous value will be restored
\&    {   $obj\->foo( 2 => \emy $x );
\&        print $obj\->foo, \*(Aq \*(Aq, $x;   # will print \*(Aq2 2\*(Aq
\&    }
\&    print $obj\->foo;                # will print 1
.Ve
.PP
Note that all accessors are read/write for everyone. See the \f(CW\*(C`TODO\*(C'\fR
section for details.
.ie n .Sh "@list\fP = \f(CW$self\->ls_accessors;"
.el .Sh "\f(CW@list\fP = \f(CW$self\fP\->ls_accessors;"
.IX Subsection "@list = $self->ls_accessors;"
Returns a list of accessors that are supported by the current object.
The corresponding coderefs can be retrieved by passing this list one
by one to the \f(CW\*(C`can\*(C'\fR method.
.ie n .Sh "$ref\fP = \f(CW$self\->ls_allow(\s-1KEY\s0)"
.el .Sh "\f(CW$ref\fP = \f(CW$self\fP\->ls_allow(\s-1KEY\s0)"
.IX Subsection "$ref = $self->ls_allow(KEY)"
Returns the allow handler for the given key, which can be used with
\&\f(CW\*(C`Params::Check\*(C'\fR's \f(CW\*(C`allow()\*(C'\fR handler. If there was no allow handler
specified, an allow handler that always returns true will be returned.
.ie n .Sh "$clone\fP = \f(CW$self\->mk_clone;"
.el .Sh "\f(CW$clone\fP = \f(CW$self\fP\->mk_clone;"
.IX Subsection "$clone = $self->mk_clone;"
Makes a clone of the current object, which will have the exact same
accessors as the current object, but without the data stored in them.
.ie n .Sh "$bool\fP = \f(CW$self\->mk_flush;"
.el .Sh "\f(CW$bool\fP = \f(CW$self\fP\->mk_flush;"
.IX Subsection "$bool = $self->mk_flush;"
Flushes all the data from the current object; all accessors will be
set back to their default state of \f(CW\*(C`undef\*(C'\fR.
.PP
Returns true on success and false on failure.
.ie n .Sh "$bool\fP = \f(CW$self\->mk_verify;"
.el .Sh "\f(CW$bool\fP = \f(CW$self\fP\->mk_verify;"
.IX Subsection "$bool = $self->mk_verify;"
Checks if all values in the current object are in accordance with their
own allow handler. Specifically useful to check if an empty initialised
object has been filled with values satisfying their own allow criteria.
.ie n .Sh "$bool\fP = \f(CW$self\->register_callback( sub { ... } );"
.el .Sh "\f(CW$bool\fP = \f(CW$self\fP\->register_callback( sub { ... } );"
.IX Subsection "$bool = $self->register_callback( sub { ... } );"
This method allows you to register a callback, that is invoked
every time an accessor is called. This allows you to munge input
data, access external data stores, etc.
.PP
You are free to return whatever you wish. On a \f(CW\*(C`set\*(C'\fR call, the
data is even stored in the object.
.PP
Below is an example of the use of a callback.
.PP
.Vb 1
\&    $object\->some_method( "some_value" );
\&    
\&    my $callback = sub {
\&        my $self    = shift; # the object
\&        my $meth    = shift; # "some_method"
\&        my $val     = shift; # ["some_value"]  
\&                             # could be undef \-\- check \*(Aqexists\*(Aq;
\&                             # if scalar @$val is empty, it was a \*(Aqget\*(Aq
\&    
\&        # your code here
\&
\&        return $new_val;     # the value you want to be set/returned
\&    }
.Ve
.PP
To access the values stored in the object, circumventing the
callback structure, you should use the \f(CW\*(C`_\|_\|_get\*(C'\fR and \f(CW\*(C`_\|_\|_set\*(C'\fR methods
documented further down.
.ie n .Sh "$bool\fP = \f(CW$self\->can( \s-1METHOD_NAME\s0 )"
.el .Sh "\f(CW$bool\fP = \f(CW$self\fP\->can( \s-1METHOD_NAME\s0 )"
.IX Subsection "$bool = $self->can( METHOD_NAME )"
This method overrides \f(CW\*(C`UNIVERAL::can\*(C'\fR in order to provide coderefs to
accessors which are loaded on demand. It will behave just like
\&\f(CW\*(C`UNIVERSAL::can\*(C'\fR where it can \*(-- returning a class method if it exists,
or a closure pointing to a valid accessor of this particular object.
.PP
You can use it as follows:
.PP
.Vb 5
\&    $sub = $object\->can(\*(Aqsome_accessor\*(Aq);   # retrieve the coderef
\&    $sub\->(\*(Aqfoo\*(Aq);                          # \*(Aqsome_accessor\*(Aq now set
\&                                            # to \*(Aqfoo\*(Aq for $object
\&    $foo = $sub\->();                        # retrieve the contents
\&                                            # of \*(Aqsome_accessor\*(Aq
.Ve
.PP
See the \f(CW\*(C`SYNOPSIS\*(C'\fR for more examples.
.ie n .Sh "$val\fP = \f(CW$self\->_\|_\|_get( \s-1METHOD_NAME\s0 );"
.el .Sh "\f(CW$val\fP = \f(CW$self\fP\->_\|_\|_get( \s-1METHOD_NAME\s0 );"
.IX Subsection "$val = $self->___get( METHOD_NAME );"
Method to directly access the value of the given accessor in the
object. It circumvents all calls to allow checks, callbakcs, etc.
.PP
Use only if you \f(CW\*(C`Know What You Are Doing\*(C'\fR! General usage for 
this functionality would be in your own custom callbacks.
.ie n .Sh "$bool\fP = \f(CW$self\->_\|_\|_set( \s-1METHOD_NAME\s0 => \s-1VALUE\s0 );"
.el .Sh "\f(CW$bool\fP = \f(CW$self\fP\->_\|_\|_set( \s-1METHOD_NAME\s0 => \s-1VALUE\s0 );"
.IX Subsection "$bool = $self->___set( METHOD_NAME => VALUE );"
Method to directly set the value of the given accessor in the
object. It circumvents all calls to allow checks, callbakcs, etc.
.PP
Use only if you \f(CW\*(C`Know What You Are Doing\*(C'\fR! General usage for 
this functionality would be in your own custom callbacks.
.SH "LVALUE ACCESSORS"
.IX Header "LVALUE ACCESSORS"
\&\f(CW\*(C`Object::Accessor\*(C'\fR supports \f(CW\*(C`lvalue\*(C'\fR attributes as well. To enable
these, you should create your objects in the designated namespace,
\&\f(CW\*(C`Object::Accessor::Lvalue\*(C'\fR. For example:
.PP
.Vb 3
\&    my $obj = Object::Accessor::Lvalue\->new(\*(Aqfoo\*(Aq);
\&    $obj\->foo += 1;
\&    print $obj\->foo;
.Ve
.PP
will actually print \f(CW1\fR and work as expected. Since this is an
optional feature, that's not desirable in all cases, we require
you to explicitly use the \f(CW\*(C`Object::Accessor::Lvalue\*(C'\fR class.
.PP
Doing the same on the standard \f(CW\*(C`Object\*(C'\fR>Accessor> class would
generate the following code & errors:
.PP
.Vb 2
\&    my $obj = Object::Accessor\->new(\*(Aqfoo\*(Aq);
\&    $obj\->foo += 1;
\&
\&    Can\*(Aqt modify non\-lvalue subroutine call
.Ve
.PP
Note that \f(CW\*(C`lvalue\*(C'\fR support on \f(CW\*(C`AUTOLOAD\*(C'\fR routines is a
\&\f(CW\*(C`perl 5.8.x\*(C'\fR feature. See perldoc perl58delta for details.
.Sh "\s-1CAVEATS\s0"
.IX Subsection "CAVEATS"
.IP "\(bu" 4
Allow handlers
.Sp
Due to the nature of \f(CW\*(C`lvalue subs\*(C'\fR, we never get access to the
value you are assigning, so we can not check it againt your allow
handler. Allow handlers are therefor unsupported under \f(CW\*(C`lvalue\*(C'\fR
conditions.
.Sp
See \f(CW\*(C`perldoc perlsub\*(C'\fR for details.
.IP "\(bu" 4
Callbacks
.Sp
Due to the nature of \f(CW\*(C`lvalue subs\*(C'\fR, we never get access to the
value you are assigning, so we can not check provide this value
to your callback. Furthermore, we can not distinguish between
a \f(CW\*(C`get\*(C'\fR and a \f(CW\*(C`set\*(C'\fR call. Callbacks are therefor unsupported 
under \f(CW\*(C`lvalue\*(C'\fR conditions.
.Sp
See \f(CW\*(C`perldoc perlsub\*(C'\fR for details.
.SH "GLOBAL VARIABLES"
.IX Header "GLOBAL VARIABLES"
.ie n .Sh "$Object::Accessor::FATAL"
.el .Sh "\f(CW$Object::Accessor::FATAL\fP"
.IX Subsection "$Object::Accessor::FATAL"
Set this variable to true to make all attempted access to non-existant
accessors be fatal.
This defaults to \f(CW\*(C`false\*(C'\fR.
.ie n .Sh "$Object::Accessor::DEBUG"
.el .Sh "\f(CW$Object::Accessor::DEBUG\fP"
.IX Subsection "$Object::Accessor::DEBUG"
Set this variable to enable debugging output.
This defaults to \f(CW\*(C`false\*(C'\fR.
.SH "TODO"
.IX Header "TODO"
.Sh "Create read-only accessors"
.IX Subsection "Create read-only accessors"
Currently all accessors are read/write for everyone. Perhaps a future
release should make it possible to have read-only accessors as well.
.SH "CAVEATS"
.IX Header "CAVEATS"
If you use codereferences for your allow handlers, you will not be able
to freeze the data structures using \f(CW\*(C`Storable\*(C'\fR.
.PP
Due to a bug in storable (until at least version 2.15), \f(CW\*(C`qr//\*(C'\fR compiled 
regexes also don't de-serialize properly. Although this bug has been 
reported, you should be aware of this issue when serializing your objects.
.PP
You can track the bug here:
.PP
.Vb 1
\&    http://rt.cpan.org/Ticket/Display.html?id=1827
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
This module by
Jos Boumans <[e-mail]>.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
This module is
copyright (c) 2004\-2005 Jos Boumans <[e-mail]>.
All rights reserved.
.PP
This library is free software;
you may redistribute and/or modify it under the same
terms as Perl itself.
.SH "POD ERRORS"
.IX Header "POD ERRORS"
Hey! \fBThe above document had some coding errors, which are explained below:\fR
.IP "Around line 700:" 4
.IX Item "Around line 700:"
You forgot a '=back' before '=head1'