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C++的Delegate模式

第七根弦 2014 年 12 月 29 日 UC, Visual Studio 发表评论 (0)

C++的Delegate模式

1.Construct the abstract delegate base class

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class Delegate {
public:
      virtual void Invoke()=0;
protected:
      Delegate(){}
      virtual ~Delegate(){}
};

2.Construct a derive class which accepts a static/global function pointer

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//NonTypeDelegate.h
#include "Delegate.h"
class NonTypeDelegate : public Delegate  
{
public:
   void Invoke();
   NonTypeDelegate(void (*pfn)(int),int iParam);
   virtual ~NonTypeDelegate(){}
private:
   void (*m_pfn)(int);
   int m_iParam;
};
//NonTypeDelegate.cpp
#include "NonTypeDelegate.h"
#include <iostream>
using namespace std;
NonTypeDelegate::NonTypeDelegate(void (*pfn)(int),
                                 int iParam):m_pfn(pfn),
                                 m_iParam(iParam)
{
}
void NonTypeDelegate::Invoke()
{
   cout << "NonTypeDelegate Invoke\r\n";
   m_pfn(m_iParam);
}

3.Construct another derive class which accepts a member function pointer

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//TypeDelegate.hpp
#include "Delegate.h"
#include <iostream>
using namespace std;
template <typename T>
class TypeDelegate : public Delegate  
{
public:
   void Invoke();
   TypeDelegate(T &t, void (T::*pfn)(int), int iParam);
   ~TypeDelegate(){}
private:
   T m_t;
   void (T::*m_pfn)(int);
   int m_iParam;
};
template<typename T>
TypeDelegate<T>::TypeDelegate(T &t,
                              void (T::*pfn)(int),
                              int iParam):m_t(t),
                              m_pfn(pfn),
                              m_iParam(iParam)
{
}
template<typename T>
void TypeDelegate<T>::Invoke()
{
   cout << "TypeDelegate Invoke\r\n";
   (m_t.*m_pfn)(m_iParam);
}

4.Now glue up all the stuffs

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#include <iostream>
#include "NonTypeDelegate.h"
#include "TypeDelegate.hpp"
#include <vector>
using namespace std;
void Test(int iParam)
{
   cout << "Test Invoked\r\n";
}
class A
{
public:
    void Test(int iParam)
    {
       cout << "A::Test Invoked\r\n";
    }
};
int main(int argc, char* argv[])
{
   NonTypeDelegate nTDelegate(Test,1);
   A a;
   TypeDelegate<A> tDelegate(a,A::Test,2);
              
   vector<Delegate*> vecpDelegate;
   vecpDelegate.push_back(&nTDelegate);
   vecpDelegate.push_back(&tDelegate);
   for (vector<Delegate*>::const_iterator kItr=vecpDelegate.begin();
       kItr!=vecpDelegate.end();
       ++kItr)
   {
       (*kItr)->Invoke();
   }
              
   return 0;
}

5.And the output is

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NonTypeDelegate Invoke
Test Invoked
TypeDelegate Invoke
A::Test Invoked

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