Taken: https://www.jianshu.com/p/621fc81a1dc1
effect:
on A package callable entities (function pointer, functor, lambda expression), such packages can function pre-bound parameter.
Example of use:
#include <iostream>
using namespace std;
void global_func(int a){//全局函数
cout<<"call global_func:"<<a<<endl;
}
auto labmda = [](int a){cout<<"lambda:"<<a<<endl;};
class ClassA{
public:
void member_func(int a){//类成员函数
cout<<"call ClassA::member_func:"<<a<<endl;
}
static void static_member_func(int a){//类静态函数
cout<<"call ClassA::static_member_func:"<<a<<endl;
}
};
class Functor{//仿函数
public:
void operator()(int a){
cout<<"call Functor()"<<a<<endl;
}
};
int main(int argc, const char * argv[]) {
function<void(int)> func;
func = global_func;
func(10);
auto bindGlobalFunc = std::bind(global_func, 10);
bindGlobalFunc();
func = labmda;
func(11);
auto bindLabmdaFunc = std::bind(labmda, 11);
bindLabmdaFunc();
Functor testFunctor;
func = testFunctor;
func(12);
auto bindFunctorFunc = std::bind(testFunctor, 12);
bindFunctorFunc();
ClassA a_object;
func = std::bind(&ClassA::member_func, &a_object, std::placeholders::_1);
func(13);
auto bindClassMemberFunc = std::bind(&ClassA::member_func,&a_object, 13);
bindClassMemberFunc();
func = std::bind(&ClassA::static_member_func, std::placeholders::_1);
func(14);
auto bindClassStaticFunc = std::bind(&ClassA::static_member_func, 14);
bindClassStaticFunc();
return 0;
}
Output:
call global_func:10
call global_func:10
lambda:11
lambda:11
call Functor()12
call Functor()12
call ClassA::member_func:13，
call ClassA::member_func:13
call ClassA::static_member_func:14
call ClassA::static_member_func:14
Precautions:
In the form of parameters are passed by value pre-bound
parameters are not pre-bound to use std :: placeholders (placeholders) in the form of mass, from the beginning of _1, in ascending order, in the form passed by reference
std :: bind the return value is a callable entity can be directly assigned to std :: function
For the pointer bound reference type parameter, the caller needs to ensure that the life cycle there before calling
std :: placeholders represent the new callable object of several parameters of the original function of several parameters and match
