【转】bind简单示例

bind简单示例代码

namespace
{
    class placeholder_ {};
    placeholder_ __1;
}

template <typename R, typename T, typename Arg>
class simple_bind_t
{
private:
    typedef R (T::*F)(Arg);
    F f_;
    T* t_;
    Arg& a_;

public:
    simple_bind_t(F f, T* t, Arg &a)
        : f_(f), t_(t), a_(a)
    {}

    R operator()()
    {
        return (t_->*f_)(a_);
    }
};

template <typename R, typename T, typename Arg>
class simple_bind_t2
{
private:
    typedef R (T::*F)(Arg);
    F f_;
    T* t_;

public:
    simple_bind_t2(F f, T* t)
        : f_(f), t_(t)
    {}

    R operator()(Arg& a)
    {
        return (t_->*f_)(a);
    }
};

template <typename R, typename T, typename Arg>
simple_bind_t<R, T, Arg> simple_bind(R (T::*f)(Arg), T* t, Arg& a)
{
    return simple_bind_t<R, T, Arg>(f, t, a);
}

template <typename R, typename T, typename Arg>
simple_bind_t2<R, T, Arg> simple_bind(R (T::*f)(Arg), T* t, placeholder_& a)
{
    return simple_bind_t2<R, T, Arg>(f, t);
}

class bind_test
{
public:
    void print_string(const std::string str)
    {
        printf("%s", str.c_str());
    }
};

void test()
{
    bind_test t;
    std::string h = "hehe\n";
    simple_bind(&bind_test::print_string, &t, h)();
    simple_bind(&bind_test::print_string, &t, __1)(h);
    boost::function<void (const std::string)> f;
    f = simple_bind(&bind_test::print_string, &t, __1);
    f(h);
}

运行结果

test函数返回结果应该是:
hehe
hehe
hehe