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The facade pattern (or façade pattern) is a software design pattern commonly used with object-oriented programming. The name is by analogy to an architectural facade. A facade is an object that provides a simplified interface to a larger body of code, such as a class library. A facade can: * make a software library easier to use, understand and test, since the facade has convenient methods for common tasks; * make the library more readable, for the same reason; * reduce dependencies of outside code on the inner workings of a library, since most code uses the facade, thus allowing more flexibility in developing the system; * wrap a poorly designed collection of APIs with a single well-designed API. The Facade design pattern is often used when a system is very complex or difficult to understand because the system has a large number of interdependent classes or its source code is unavailable. This pattern hides the complexities of the larger system and provides a simpler interface to the client. It typically involves a single wrapper class which contains a set of members required by client. These members access the system on behalf of the facade client and hide the implementation details. == Usage == A Facade is used when an easier or simpler interface to an underlying object is desired. Alternatively, an adapter can be used when the wrapper must respect a particular interface and must support polymorphic behavior. A decorator makes it possible to add or alter behavior of an interface at run-time. The facade pattern is typically used when: * a simple interface is required to access a complex system; * the abstractions and implementations of a subsystem are tightly coupled; * need an entry point to each level of layered software; or * a system is very complex or difficult to understand. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Facade pattern」の詳細全文を読む スポンサード リンク
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