首先聲明,並不涉及std::function 的使用,留作下次吧
bind 用來綁定一個函數,包括 全局函數, 普通成員函數, 靜態成員函數, operator函數, 虛函數
但是不包括重載函數,原因是,通過函數名並不知道 因爲無法確定需要哪個重載函數實例(vs2013),
理論就這些吧
#include<iostream>
#include<functional>
using namespace std;
int add1(int i, int j, int k)
{
return i + j + k;
}
typedef std::function<void() > fp;
class A
{
public:
A(string& say) :say_(say){}
void foo(string para)
{
cout <<"A::foo():"<< "say_:\t"<< say_.c_str() <<"\tpara:\t"<<para.c_str() << endl;
}
/*void foo(int a, string para)
{
cout << "say_:\t" << say_.c_str() << " para:\t" << para.c_str()<<" a:"<<a << endl;
}*/
virtual void f()
{
cout << "A::f()" << endl;
}
static const string getId()
{
cout << "static const string getId():";
return num_sta;
}
int operator()(int i, int j) const
{
return i + j;
}
void init()
{
//std::bind可以表現出多態的行爲
fp f_ = std::bind(&A::f, this);
f_();
}
private:
string say_;
static string num_sta;
};
class B :public A
{
public:
B(string a):A(a){}
virtual void f()
{
cout << "B::f()" << endl;
}
};
string A::num_sta = "static number";
int main()
{
//綁定全局函數
{
// 函數add2 = 綁定add1函數,參數1不變,參數2不變,參數3固定爲10
auto add2 = std::bind(add1, std::placeholders::_1, std::placeholders::_2, 10);
std::cout << typeid(add2).name() << endl;
std::cout << "add2(1,2):\t" << add2(1, 2) << endl;
std::cout << "___________________________" << endl;
//函數add2 = 綁定add1函數, 三個參數都不變
auto add3 = std::bind(add1, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3);
int i = 0;
while (i < 3)
std::cout << "add2(1,2," << i << ")\t" << add3(1, 2, i++) << "\n" << endl;
std::cout << "___________________________" << endl;
}
//綁定成員函數
{
string say("string say()");
A a(say);
//普通成員函數,(成員函數名,所屬類對象,需要綁定的參數和指定的參數)
//不能綁定重載函數,因爲無法確定需要哪個重載函數實例
auto bind_foo = std::bind(&A::foo /*要綁定對象*/, a /*所屬對象(調用者)*/, std::placeholders::_1);
bind_foo(say);
//靜態成員函數(靜態成員函數名,沒有所屬類對象!!
auto bind_static = std::bind(&A::getId);
cout << "bind_static():\t" << bind_static().c_str() << endl;
std::cout << "___________________________" << endl;
//operator函數(和綁定成員函數一樣)
auto bind_operator = std::bind(&A::operator(), a, std::placeholders::_1, std::placeholders::_2);
cout << "bind_operator(5, 10):\t" << bind_operator(5, 10) << endl;
std::cout << "___________________________" << endl;
}
//綁定虛函數
{
A* pa = new B("new B");
pa->init();
}
return 0;
}