C++类重载函数的function和bind使用示例

#include <unordered_map>
#include <iostream>
#include <functional>
using namespace std;
int func(int a)
{
  cout << a << __FUNCTION__ << endl;
  return a;
}
int main()
{
  using NewType = function<int(int)>; // function本质上生成了一个类(仿函数)
  NewType f1 = func;
  f1(55);
  return 0;
}

#include <unordered_map>
#include <iostream>
#include <functional>
using namespace std;
class A
{
public:
  int funcA(int a)
  {
    cout << "111 " << a << endl;
    return 1;
  }
};

int main()
{
  A a;
  using NewType = function<int(int)>; // function本质上生成了一个类(仿函数)
  NewType f1 = bind(&A::funcA, &a, std::placeholders::_1);
  f1(55);
  return 0;
}

#include <unordered_map>
#include <iostream>
#include <functional>
using namespace std;
class A
{
public:
  int funcA(int a)
  {
    cout << "111 " << a << endl;
    return 1;
  }
  int funcA(int a, int b)
  {
    cout << "222 " << a << endl;
    return a + b;
  }
};

int main()
{
  unordered_map<int, void *> funcMap;//尝试将其转载入map中
  A g;
  using NewType1 = function<int(int, int)>; 
  using NewType2 = function<int(int)>;
  NewType1* type1 = new NewType1; // function本质上生成了一个类(仿函数)
  NewType2* type2 = new NewType2;
  //获取重载函数指针
  *type1 = std::bind((int(A::*)(int, int)) & A::funcA, &g, std::placeholders::_1, std::placeholders::_2);
  *type2 = std::bind((int(A::*)(int)) & A::funcA, &g, std::placeholders::_1);
  //
  funcMap[1] = type1; //
  funcMap[2] = type2; //
  
  // 使用
  void* s1 = funcMap[1];
  void* s2 = funcMap[2];
  NewType1* f1 = (NewType1*)(s1);
  NewType2* f2 = (NewType2*)(s2);
  (*f1)(1,5);
  (*f2)(55);
  return 0;
}