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The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects. This pattern is used to: * avoid subclasses of an object creator in the client application, like the abstract factory pattern does. * avoid the inherent cost of creating a new object in the standard way (e.g., using the 'new' keyword) when it is prohibitively expensive for a given application. To implement the pattern, declare an abstract base class that specifies a pure virtual ''clone()'' method. Any class that needs a "polymorphic constructor" capability derives itself from the abstract base class, and implements the ''clone()'' operation. The client, instead of writing code that invokes the "new" operator on a hard-coded class name, calls the ''clone()'' method on the prototype, calls a factory method with a parameter designating the particular concrete derived class desired, or invokes the ''clone()'' method through some mechanism provided by another design pattern. The mitotic division of a cell — resulting in two identical cells — is an example of a prototype that plays an active role in copying itself and thus, demonstrates the Prototype pattern. When a cell splits, two cells of identical genotype result. In other words, the cell clones itself.〔Michael Duell, "Non-software examples of software design patterns", Object Magazine, Jul 97, p. 54〕 ==Structure== 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「Prototype pattern」の詳細全文を読む スポンサード リンク
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