C++11 std::bind std::function 变参函数
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从最基础的了解,std::bind和std::function
- /*
- * File: main.cpp
- * Author: Vicky.H
- * Email: eclipser@163.com
- */
- #include <iostream>
- #include <functional>
- #include <typeinfo>
- #include <string.h>
- int add1(int i, int j, int k) {
- return i + j + k;
- }
- class Utils {
- public:
- Utils(const char* name) {
- strcpy(_name, name);
- }
- void sayHello(const char* name) const {
- std::cout << _name << " say: hello " << name << std::endl;
- }
- static int getId() {
- return 10001;
- }
- int operator()(int i, int j, int k) const {
- return i + j + k;
- }
- private:
- char _name[32];
- };
- /*
- *
- */
- int main(void) {
- // 绑定全局函数
- auto add2 = std::bind(add1, std::placeholders::_1, std::placeholders::_2, 10);
- // 函数add2 = 绑定add1函数,参数1不变,参数2不变,参数3固定为10.
- std::cout << typeid(add2).name() << std::endl;
- std::cout << "add2(1,2) = " << add2(1, 2) << std::endl;
- std::cout << "\n---------------------------" << std::endl;
- // 绑定成员函数
- Utils utils("Vicky");
- auto sayHello = std::bind(&Utils::sayHello, utils/*调用者*/, std::placeholders::_1/*参数1*/);
- sayHello("Jack");
- auto sayHelloToLucy = std::bind(&Utils::sayHello, utils/*调用者*/, "Lucy"/*固定参数1*/);
- sayHelloToLucy();
- // 绑定静态成员函数
- auto getId = std::bind(&Utils::getId);
- std::cout << getId() << std::endl;
- std::cout << "\n---------------------------" << std::endl;
- // 绑定operator函数
- auto add100 = std::bind(&Utils::operator (), utils, std::placeholders::_1, std::placeholders::_2, 100);
- std::cout << "add100(1, 2) = " << add100(1, 2) << std::endl;
- // 注意:无法使用std::bind()绑定一个重载函数
- return 0;
- }
- /*
- * File: main2.cpp
- * Author: Vicky.H
- * Email: eclipser@163.com
- */
- #include <iostream>
- #include <typeinfo>
- void sayHello() {
- std::cout << "Hello world !" << std::endl;
- }
- int sum(int i, int j, int k) {
- return i + j + k;
- }
- template <typename T>
- class Func {
- public:
- Func(T fun) {
- if (!fun) {
- throw "fun nullptr";
- }
- _fun = fun;
- }
- template<typename R, typename A1, typename A2, typename A3, typename A4, typename A5>
- R Call(A1 a1, A2 a2, A3 a3, A4 a4, A5 a5) {
- return _fun(a1, a2, a3, a4, a5);
- }
- template<typename R, typename A1, typename A2, typename A3, typename A4>
- R Call(A1 a1, A2 a2, A3 a3, A4 a4) {
- return _fun(a1, a2, a3, a4);
- }
- template<typename R, typename A1, typename A2, typename A3>
- R Call(A1 a1, A2 a2, A3 a3) {
- return _fun(a1, a2, a3);
- }
- template<typename R, typename A1, typename A2>
- R Call(A1 a1, A2 a2) {
- return _fun(a1, a2);
- }
- template<typename R, typename A1>
- R Call(A1 a1) {
- return _fun(a1);
- }
- template<typename R>
- R Call() {
- return _fun();
- }
- void Call() {
- _fun();
- }
- private:
- T _fun;
- };
- #include <functional>
- template<typename R = void, typename... Args>
- class Fn {
- public:
- Fn(std::function<R(Args...)> fun) : _fun(fun) {
- }
- R operator()(Args... args) {
- return _fun(args...);
- }
- private:
- std::function<R(Args...) > _fun;
- };
- /*
- * 将函数注册到对象中,通过对象直接调用
- */
- int main(void) {
- Func<void(*)() > sayHelloFunc(sayHello);
- sayHelloFunc.Call();
- Func<int (*)(int, int, int) > sumFunc(sum);
- std::cout << "sumFunc.Call<int>(1, 2, 3) : " << sumFunc.Call<int>(1, 2, 3) << std::endl;
- std::cout << "\n---------------------------" << std::endl;
- Fn<> sayHelloFn(sayHello);
- sayHelloFn();
- Fn<int, int, int, int> sumFn(sum);
- std::cout << "sumFn(1, 2, 3) : " << sumFn(1, 2, 3) << std::endl;
- std::cout << "\n---------------------------" << std::endl;
- return 0;
- }
Hello world !
sumFunc.Call<int>(1, 2, 3) : 6
---------------------------
Hello world !
sumFn(1, 2, 3) : 6
---------------------------
上面的例子非常有趣,使用了2种方案,将一个函数,注册到一个对象/仿函数中,并且通过一个对象/仿函数来直接调用调用。
例子显而易见的,第2种方案更佳简洁,并且对传递参数有明确的判断,当参数类型或数量不正确的时候,编译器将导致失败。
这种方案,可以将类的成员变量直接作为函数的参数使用,或者,如我:
http://blog.csdn.net/eclipser1987/article/details/23926395
这篇文章中,无法直接调用脚本函数类,有了好的解决办法。这个我将随后补充。
- #include <list>
- #include <functional>
- template<typename... Args>
- class Fns
- {
- private:
- std::list<std::function<void(Args...)> > _calls;
- public:
- virtual ~Fns()
- {
- _calls.clear();
- }
- void connect(std::function<void(Args...)> fct)
- {
- _calls.push_back(fct);
- }
- template<typename Object>
- void connect(Object* object, void (Object::*method)(Args...))
- {
- _calls.push_back([object,method](Args... args){(*object.*method)(args...);});
- }
- template<typename Object>
- void connect(Object* object, void (Object::*method)(Args...) const)
- {
- _calls.push_back([object,method](Args... args){(*object.*method)(args...);});
- }
- template<typename Object>
- void connect(const Object* object, void (Object::*method)(Args...) const)
- {
- _calls.push_back([object,method](Args... args){(*object.*method)(args...);});
- }
- void emit(Args... args)
- {
- for(auto call : _calls)
- call(args...);
- }
- };
- #include <cstdio>
- #include "Signal.hpp"
- class Foo
- {
- public:
- void bar(int x, int y)
- {
- printf("Foo::bar(%d, %d)\n", x, y);
- }
- };
- void foobar(int x, int y)
- {
- printf("foobar(%d, %d)\n", x, y);
- }
- int main(void)
- {
- Foo foo;
- Fns<int, int> s;
- // Connect a function
- s.connect(foobar);
- // Connect a class method
- s.connect(&foo, &Foo::bar);
- // Create and connect some lambda expression
- s.connect([&foo](int x, int y){
- printf("lambda::"); foo.bar(x, y);
- });
- // Emit the signal !
- s.emit(4, 2);
- getchar();
- return 0;
- }
foobar(4, 2)
Foo::bar(4, 2)
lambda::Foo::bar(4, 2)
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