...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
The class template function_traits extracts information from function types (see also is_function). This traits class allows you to tell how many arguments a function takes, what those argument types are, and what the return type is.
Synopsis
template <std::size_t Align> struct function_traits;