Adapter

Origin:

GoF 95

Reason:

A client needs the service of an object, Obj, through an interface, IF, but Obj does not implement IF.

Synopsis:

Define a class, the Adapter, that implements interface IF and provides the service via Obj.

Example:

A method copies arrays filtering out some elements. The criterion to filter out an element is defined by an interface, CopyFilterIF. Array elements that have the information for the filtering criterion may not implement CopyFilterIF.

Solution:

Client	Class that needs a service through interface TargetIF.
TargetIF	Interface expected by Client to obtain a service.
Adapter	Class that implements TargetIF and provides the service using Adaptee.
Adaptee	Class that does not implement TargetIF and provides the service.