Class::Adapter::Clear - A handy base Adapter class that makes no changes
version 1.09
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, @_); }
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.
Class::Adapter::Clear
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.
->isa
->can
It looks like a Duck, and it quacks like a Duck.
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.
CODE
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;
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.
new
Returns a new Class::Adapter::Clear object, or undef if you do not pass in an object.
undef
Class::Adapter, Class::Adapter::Builder
Bugs may be submitted through the RT bug tracker (or bug-Class-Adapter@rt.cpan.org).
Adam Kennedy <adamk@cpan.org>
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.
To install Class::Adapter, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Class::Adapter
CPAN shell
perl -MCPAN -e shell install Class::Adapter
For more information on module installation, please visit the detailed CPAN module installation guide.