Design pattern--Prototype mode C + + implementation

Prototype Mode C + + implementation 1 definition

Specify the kind of objects created with the prototype instance and create new objects by copying the prototypes

2 class Diagram

3 implementation

Class Prototype

{

Protected

Prototype ();

Public

Virtual prototype* Clone () const = 0;

Vitual ~prototype () = 0;

};

Class Prototypeclass:public Prototype

{

Public

Prototypeclass ();

Prototypeclass (const PROTOTYPECLASS & CP);

prototype* Clone () const

{return 0;}

};

Note: The key to the prototype model in C + + is the implementation of the copy constructor.

Factory mode, builder mode, and prototype mode all construct new objects through existing class objects, except

Factory mode: Focus on mass production of multiple interdependent classes of objects

Builder mode: Step-up creation with emphasis on complex objects

Prototype mode: Implement new object construction by copying itself

4 applications

Advantages

Good performance, avoid the constraints of the constructor function.

5 Usage Scenarios

① Resource optimization scenario, class initialization requires a large resource (data, hardware)

② Performance and security requirements, data preparation and permissions issues with new frequent production

③ an object with multiple modified scenes, eg student Information form.

6 precautions

Constructor will not be executed

A deep copy problem, when the inside of a class contains pointers, it is necessary to implement a dark copy yourself.

Design pattern--Prototype mode C + + implementation