/ 
Class-Adapter-1.09
River stage two • 2 direct dependents • 80 total dependents
/ Class::Adapter::Clear

NAME

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

VERSION

version 1.09

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.

SEE ALSO

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

SUPPORT

Bugs may be submitted through the RT bug tracker (or bug-Class-Adapter@rt.cpan.org).

AUTHOR

Adam Kennedy <adamk@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2005 by Adam Kennedy.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.