Home > Backend Development > C++ > How to Retrieve Function Argument Types in a Variadic Template Class?

How to Retrieve Function Argument Types in a Variadic Template Class?

Mary-Kate Olsen
Release: 2024-11-01 10:17:30
Original
514 people have browsed it

How to Retrieve Function Argument Types in a Variadic Template Class?

Retrieving Function Argument Types in a Variadic Template Class

The specified functor class, Foo, provides a means to invoke functions with arbitrary argument lists. However, determining the argument types within the constructor presents a challenge.

To overcome this, you can utilize the function_traits class as follows:

<code class="cpp">template<typename T>
struct function_traits;

template<typename R, typename ...Args>
struct function_traits<std::function<R(Args...)>>
{
    static const size_t nargs = sizeof...(Args);

    typedef R result_type;

    template <size_t i>
    struct arg
    {
        typedef typename std::tuple_element<i, std::tuple<Args...>>::type type;
    };
};</code>
Copy after login

Within the Foo class, you can employ function_traits to obtain the argument type information:

<code class="cpp">class Foo
{
    std::function<void(ARGS...)> m_f;
public:
    using result_type = typename function_traits<decltype(m_f)>::result_type;
    using arg0_type = typename function_traits<decltype(m_f)>::arg<0>::type;
    // ... Additional argument types as needed
};</code>
Copy after login

This approach allows you to leverage the type system to access and manipulate the function argument types in a generic and type-safe manner.

The above is the detailed content of How to Retrieve Function Argument Types in a Variadic Template Class?. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template