Agent mode (proxy) C + + implementation

Proxy mode

Although the implementation of decorator is similar to a proxy, the purpose of decorator is different. Decorator adds one or more functions to an object, while the delegate controls access to the object.

Intention:

Provides a proxy for other objects to control access to this object.

Applicability:

Use proxy mode when you need to replace simple pointers with more generic and complex object pointers.

1, the remote agent , that is, for an object in different address space to provide local representation. This can hide the fact that an object exists in a different address space.

2, virtual Agent , is based on the need to create a large cost of objects. It is the real object that takes a long time to store the instantiation.

3, security agent , to control the real object access permissions.

4, Smart guidance , instead of a simple pointer, it performs some additional operations when accessing an object.

Uml:

　　　　

Participants:

Proxy

-Save a reference so that the agent can access the entity. If the interface of Realsubject and subject is the same, proxy references subject.

-Provides an interface with the same interface as the subject, so that proxies can be used instead of entities.

-Controls access to the entity and may be responsible for creating and deleting it.

-Other features depend on the type of proxy.

Subject

-Define the common interface of realsubject and proxy, so that you can use proxy in any place where you use Realsubject.

Realsubject

-Define the entity represented by the proxy.

Code implementation:

Agent mode (proxy) C + + implementation