NAME
Class::Adapter - Perl implementation of the "Adapter" Design Pattern
DESCRIPTION
The "Class::Adapter" class is intended as an abstract base class for
creating any sort of class or object that follows the *Adapter* pattern.
What is an Adapter?
The term *Adapter* refers to a *"Design Pattern"* of the same name, from
the famous *"Gang of Four"* book *"Design Patterns"*. Although their
original implementation was designed for Java and similar
single-inheritance strictly-typed langauge, the situation for which it
applies is still valid.
An *Adapter* in this Perl sense of the term is when a class is created
to achieve by composition (objects containing other object) something
that can't be achieved by inheritance (sub-classing).
This is similar to the *Decorator* pattern, but is intended to be
applied on a class-by-class basis, as opposed to being able to be
applied one object at a time, as is the case with the *Decorator*
pattern.
The "Class::Adapter" object holds a parent object that it "wraps", and
when a method is called on the "Class::Adapter", it manually calls the
same (or different) method with the same (or different) parameters on
the parent object contained within it.
Instead of these custom methods being hooked in on an object-by-object
basis, they are defined at the class level.
Basically, a "Class::Adapter" is one of your fall-back positions when
Perl's inheritance model fails you, or is no longer good enough, and you
need to do something twisty in order to make several APIs play nicely
with each other.
What can I do with the actual Class::Adapter class
Well... nothing really. It exist to provide some extremely low level
fundamental methods, and to provide a common base for inheritance of
Adapter classes.
The base "Class::Adapter" class doesn't even implement a way to push
method calls through to the underlying object, since the way in which
that happens is the bit that changes from case to case.
To actually DO something, you probably want to go take a look at
Class::Adapter::Builder, which makes the creation of *Adapter* classes
relatively quick and easy.
METHODS
The "Class::Adapter" class itself supplies only the two most common
methods, a default constructor and a private method to access the
underlying object.
new $object
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" object, or "undef" if you do not pass in
an object.
_OBJECT_
The "_OBJECT_" method is provided primarily as a convenience, and a tool
for people implementing sub-classes, and allows the "Class::Adapter"
interface to provide a guarenteed correct way of getting to the
underlying object, should you need to do so.
SUPPORT
Bugs should be reported via the CPAN bug tracker at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Class-Adapter>
For other issues, contact the author.
TO DO
- Write more comprehensive tests
AUTHOR
Adam Kennedy <
[email protected]>
SEE ALSO
Class::Adapter::Clear, Class::Adapter::Builder, Class::Decorator
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.
