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Class::Adapter::Clear.3pm

NAME

Class::Adapter::Clear - A handy base Adapter class that makes no changes

SYNOPSIS

Hello World with CGI.pm the normal way

   # Load and create the CGI
   use CGI;
   $q = new CGI;
   
   # Create the page
   print $q->header,                    # HTTP Header
         $q->start_html('hello world'), # Start the page
         $q->h1('hello world'),         # Hello World!
         $q->end_html;                  # End the page
 
 

Hello World with CGI.pm the Adapter'ed way

   # Load and create the CGI
   use CGI;
   $q = new CGI;
   
   # Convert to an Adapter
   use Class::Adapter::Clear;
   $q = new Class::Adapter::Clear( $q );
   
   # Create the page
   print $q->header,                    # HTTP Header
         $q->start_html('hello world'), # Start the page
         $q->h1('hello world'),         # Hello World!
         $q->end_html;                  # End the page
 
 

Creating a CGI Adapter class using Class::Adapter::Clear

   package My::CGI;
   
   use base 'Class::Adapter::Clear';
   
   # Optional - Create the thing we are decorating auto-magically
   sub new {
       my $class = shift;
   
       # Create the object we are decorating
       my $query = CGI->new(@_);
   
       # Wrap it in the Adapter
       $class->SUPER::new($query);
   }
   
   # Decorate the h1 method to change what is created
   sub h1 {
         my $self = shift;
         my $str  = shift;
   
     # Do something before the real method call
     if ( defined $str and $str eq 'hello world' ) {
         $str = 'Hello World!';
     }
     
     $self->_OBJECT_->($str, @_);
   }
 
 

DESCRIPTION

"Class::Adapter::Clear" provides the base class for creating one common type of Class::Adapter classes. For more power, move up to Class::Adapter::Builder.

On it's own "Class::Adapter::Clear" passes all methods through to the same method in the parent object with the same parameters, responds to "->isa" like the parent object, and responds to "->can" like the parent object.

It looks like a "Duck", and it quacks like a "Duck".

On this base, you simple implement whatever method you want to do something special to.

   # Different method, same parameters
   sub method1 {
       my $self = shift;
       $self->_OBJECT_->method2(@_); # Call a different method
   }
   
   # Same method, different parameters
   sub method1 {
       my $self = shift;
       $self->_OBJECT_->method1( lc($_[0]) ); # Lowercase the param
   }
   
   # Same method, same parameters, tweak the result
   sub method1 {
       my $self = shift;
       my $rv = $self->_OBJECT_->method1(@_);
       $rv =~ s/\n/<br>\n/g; # Add line-break HTML tags at each newline
       return $rv;
   }
 
 

As you can see, the advantage of this full-scale Adapter approach, compared to inheritance, or function wrapping (see Class::Hook), is that you have complete and utter freedom to do anything you might need to do, without stressing the Perl inheritance model or doing anything unusual or tricky with "CODE" references.

You may never need this much power. But when you need it, you really need it.

As an aside, Class::Adapter::Clear is implemented with the following Class::Adapter::Builder formula.

   use Class::Adapter::Builder
       ISA      => '_OBJECT_',
       AUTOLOAD => 1;
 
 

METHODS

new $object

As does the base Class::Adapter class, the default "new" constructor takes a single object as argument and creates a new object which holds the passed object.

Returns a new "Class::Adapter::Clear" object, or "undef" if you do not pass in an object.

SUPPORT

Bugs should be reported via the CPAN bug tracker at

http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Class-Adapter <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Class-Adapter>

For other issues, contact the author.

AUTHOR

Adam Kennedy <adamk@cpan.org>

SEE ALSO

Class::Adapter, Class::Adapter::Builder

COPYRIGHT

Copyright 2005 - 2010 Adam Kennedy.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.