小编Gor*_*vić的帖子

我有像这样定义的is_callable trait:

#ifndef IS_CALLABLE_HPP
#define IS_CALLABLE_HPP

#include <type_traits>

namespace is_callable_detail
{
    struct no   {};
    struct yes  { no x[2]; };

    template<bool CallableArgs, typename Callable, typename ReturnType, typename ...Args>
    struct check_return
    {
        static const bool value = std::is_convertible<decltype(std::declval<Callable>()(std::declval<Args>()...)), ReturnType>::value;
    };

    template<typename Callable, typename ReturnType, typename ...Args>
    struct check_return<false, Callable, ReturnType, Args...>
    {
        static const bool value = false;
    };
}

template<typename Callable, typename Function>
struct is_callable;

template<typename Callable, typename ReturnType, typename ...Args>
struct is_callable<Callable, ReturnType(Args...)>
{
    private:
        template<typename T>
        static is_callable_detail::yes …