C ++ 11样式回调？ [英] C++11 styled callbacks?

问题描述

我在类中有一个void函数。在旧的C ++中，我会创建一个静态函数，将类名作为参数，并拥有一个我自己的类，它采用了一个静态void函数+ void *让我轻松调用它。

但是，感觉老学校。它也不是模板的感觉，我可以做更多。什么是更现代的方式来创建回调myclassVar.voidReturnVoidParamFunc

解决方案

使用 std :: function 和lambdas（或 std :: bind（））存储callable：

  #include< functional> 
 #include< iostream> 
 
 
 class Test 
 {
 public：
 void blah（）{std :: cout< BLAH！ << std :: endl; } 
}; 
 
 class Bim 
 {
 public：
 void operator（）（）{std :: cout< BIM！ << std :: endl; } 
}; 
 
 void boum（）{std :: cout<< BOUM！ << std :: endl; } 
 
 
 int main（）
 {
 //存储对象的成员函数：
 Test test; 
 std :: function< void（）> callback = std :: bind（& Test :: blah，test）; 
 callback（）; 
 
 //存储一个可调用的对象（通过拷贝）
 callback = Bim {}; 
 callback（）; 
 
 //存储静态函数的地址
 callback =& boum; 
 callback（）; 
 
 //存储一个lambda的副本（这是一个可调用对象）
 callback = [&] {test.blah（）; }; //通常更清晰，而不是更昂贵 - 比std :: bind（）
 callback（）; 
} 
  

结果：

< >

BLAH！

BIM！

BOUM！
$ b

BLAH！

编译并运行：http://ideone.com/T6wVp

std :: function 可以用作任何可复制对象，所以随意存储它作为一个回调，像在对象的成员。这也意味着你可以自由地把它放在标准的容器，如 std :: vector< std :: function< void（）> < a href =http://www.boost.org/doc/libs/1_51_0/> doc / html / function.html> boost :: function和boost :: bind 已有多年。

I have a void function inside of a class. In old C++ i'd make a function static taking the class name as a parameter and had my own class which took a static void function + a void* for me to easily call it.

However that feels old school. It also isn't templated which feels like i could be doing more. What is a more modern way of creating callbacks to myclassVar.voidReturnVoidParamFunc

解决方案

Use std::function and lambdas (or std::bind()) to store callables:

#include <functional>
#include <iostream>


    class Test
    {
    public:
          void blah() { std::cout << "BLAH!" << std::endl; }
    };

    class Bim
    {
    public:
          void operator()(){ std::cout << "BIM!" << std::endl; }
    };

    void boum() { std::cout << "BOUM!" << std::endl; }


int main()
{
    // store the member function of an object:
    Test test;  
    std::function< void() > callback = std::bind( &Test::blah, test );
    callback();

    // store a callable object (by copy)
    callback = Bim{};
    callback();

    // store the address of a static function
    callback = &boum;
    callback();

    // store a copy of a lambda (that is a callable object)
    callback = [&]{ test.blah(); }; // often clearer -and not more expensive- than std::bind()
    callback();
}      

Result:

BLAH!

BIM!

BOUM!

BLAH!

Compiles and run: http://ideone.com/T6wVp

std::function can be used as any copyiable object, so feel free to store it somewhere as a callback, like in object's member. It also means that you can freely put it in standard containers, like std::vector< std::function< void () > > .

Also note that equivalent boost::function and boost::bind have been available for years.

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