== Participants ==
The classes and/or objects participating in this pattern are:
====<ul><li>'''Abstraction===='''</li><ul><li>defines the abstraction's interface</li><li>maintains a reference to an object of type Implementor</li>====</ul><li>'''Refined Abstraction===='''</li><ul><li>extends the interface defined by Abstraction.</li></ul>====<li>'''Implementor===='''</li><ul><li>defines the interface for implementation classes. This interface does not have to correspond exactly to Abstraction's interface; in fact the two interfaces can be quite different. The Implementation interface provides only primitive operations, and Abstraction defines high-level operations based on these primitives. </li></ul>====<li>'''Concrete Implementor===='''</li><ul><li>implements the Implementor interface and defines its concrete implementation.</li></ul></ul>
== Consequences ==
