可包装对象

std::function模板类是一个通用的可调用对象的包装器，用简单的、统一的方式处理可调用对象。

#include <iostream>
#include<functional>
using namespace std;
void show(int age, const string& message)
{
	cout << "age " << age << "message " << message << endl;
}
class AA
{
public:
	static void show(int age, const string& message)
	{
		cout <<  "age " << age << "message " << message << endl;
	}
};
struct BB
{
	void operator()(int age, const string& message)
	{
		cout << "age " << age << "message " << message << endl;
	}
};
class CC
{
public:
	void show(int age, const string& message)
	{
		cout << "age " << age << "message " << message << endl;
	}

};
int main()
{
	using Fun = void(int, const string&);
	auto lb = [](int age, const string& message)
		{
			cout << "age " << age << "message " << message << endl;
		};
	function<void(int, const string&)> fn1 = show;
	function<void(int, const string&)> fn2 = AA::show;
	function<void(int, const string&)> fn3 = BB();
	function<void(int, const string&)> fn4 = lb;
	function<void(CC&, int, const string&)> fun5 = &CC::show;
	fn1(1,"Name");
	fn2(1, "Name");
	fn3(1, "Name");
	fn4(1, "Name");
	CC cc;
	fun5(cc,1,"Name");
}