C++ 简单代理实现

OC中有一种常用的机制，delegate代理，或者委托，可以实现不同类之间的方法互相调用，调用者不需了解被调用者，被调用者也同样，只要被调用者实现了委托函数即可，这个机制可以实现很多功能。下面就是我在C++中进行的一次尝试，粗糙的模仿，只实现了基本功能，没有实现@required,@optional等限定符功能。

#include <string>#include <iostream>using namespace std;template <class classname>class Delegate{public://代理方法，需要被executor实现void doit(){cout << "requesting" << endl;if(_ex != NULL)_ex->doit();}void operator = (classname *ex){_ex = ex;}private:classname *_ex;};class Executor;class Caller{public:Delegate<Executor> myDelegate;};class Executor{private:string _name;public:Executor(string name):_name(name){}void doit(){cout <<_name << " :doing" <<endl;}};int main(){Caller *ca = new Caller();Executor *ex1 = new Executor("first executor");Executor *ex2 = new Executor("second executor");ca->myDelegate = ex1;ca->myDelegate.doit();ca->myDelegate = ex2;ca->myDelegate.doit();delete ex1,ex2;delete ca;system("pause");return 0;}其实，在真实需要代理的情况中，更接近于下面的形式，这样可以实现两个类互相调用，而避免循环引用。

#include <iostream>using namespace std;template <class classname>class Delegate{public://代理方法，需要被executor实现void doit(){cout << "requesting" << endl;if(_ex != NULL)_ex->doit();}void operator = (classname *ex){_ex = ex;}private:classname *_ex;};class Executor;class Caller{public:Delegate<Executor> myDelegate;void callDelegate(){myDelegate.doit();}};class Executor{public:Executor(){_ca = new Caller();}~Executor(){delete _ca;}void doit(){cout << "doing" <<endl;}void registerCaller(){_ca->myDelegate = this;}//仅为测试用void callMyself(){_ca->callDelegate();}private:Caller *_ca;};int main(){Executor *ex = new Executor();ex->registerCaller();ex->callMyself();delete ex;system("pause");return 0;}