C++实现设计模式中的Interface from goolge

Classes that satisfy certain conditions are allowed, but not required, to end with an Interface suffix.
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Definition:

A class is a pure interface if it meets the following requirements:

• It has only public pure virtual ("= 0") methods and static methods (but see below for destructor).
• It may not have non-static data members.
• It need not have any constructors defined. If a constructor is provided, it must take no arguments and it must be protected.
• If it is a subclass, it may only be derived from classes that satisfy these conditions and are tagged with the Interface suffix.

An interface class can never be directly instantiated because of the pure virtual method(s) it declares. To make sure all implementations of the interface can be destroyed correctly, they must also declare a virtual destructor (in an exception to the first rule, this should not be pure). See Stroustrup, The C++ Programming Language, 3rd edition, section 12.4 for details.

Pros: Tagging a class with the Interface suffix lets others know that they must not add implemented methods or non static data members. This is particularly important in the case of multiple inheritance. Additionally, the interface concept is already well-understood by Java programmers.

Cons: The Interface suffix lengthens the class name, which can make it harder to read and understand. Also, the interface property may be considered an implementation detail that shouldn't be exposed to clients.

Decision: A class may end with Interface only if it meets the above requirements. We do not require the converse, however: classes that meet the above requirements are not required to end with Interface.

Posted on 2008-10-07 14:39 micheal's tech 阅读(223) 评论(0)   编辑  收藏 引用 所属分类: C++ programme language 、 设计模式