C++ 11: function & bind 使用示例

#include <functional>

struct Foo {

    Foo(int num) : num_(num) {}

    void print_add(int i) const { std::cout << num_+i << '\n'; }

    int num_;

};

void print_num(int i)

{

    std::cout << i << '\n';

}

struct PrintNum {

    void operator()(int i) const

    {

        std::cout << i << '\n';

    }

};

int main()

{

    // store a free function

    std::function<void(int)> f_display = print_num;

    f_display(-9);

    // store a lambda

    std::function<void()> f_display_42 = []() { print_num(42); };

    f_display_42();

    // store the result of a call to std::bind

    std::function<void()> f_display_31337 = std::bind(print_num, 31337);

    f_display_31337();

    // store a call to a member function

    std::function<void(const Foo&, int)> f_add_display = &Foo::print_add;

    const Foo foo(314159);

    f_add_display(foo, 1);

    // store a call to a member function and object

    using std::placeholders::_1;

    std::function<void(int)> f_add_display2= std::bind( &Foo::print_add, foo, _1 );

    f_add_display2(2);

    // store a call to a function object

    std::function<void(int)> f_display_obj = PrintNum();

    f_display_obj(18);

}