diff --git a/README.md b/README.md index 2bb87be4b..73f9ca66a 100644 --- a/README.md +++ b/README.md @@ -64,6 +64,16 @@ ##Bridge **Intent:** Decouple an abstraction from its implementationso that the two can vary independently. + +![alt text](https://github.com/iluwatar/java-design-patterns/blob/master/bridge/etc/bridge.jpg "Bridge") + +**Applicability:** Use the Bridge pattern when +* you want to avoid a permanent binding between an abstraction and its implementation. This might be the case, for example, when the implementation must be selected or switched at run-time. +* both the abstractions and their implementations should be extensible by subclassing. In this case, the Bridge pattern lets you combine the different abstractions and implementations and extend them independently +* changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled. +* you have a proliferation of classes. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" to refer to such class hierarchies +* you want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class, in which multiple objects can share the same string representation. + ##Composite **Intent:** Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.