| Defined in header
<type_traits> | ||
|---|---|---|
template <class, class R = void> struct is_callable; // not defined template <class Fn, class... ArgTypes, class R> struct is_callable<Fn(ArgTypes...), R>; | (1) | (since C++17) |
template <class, class R = void> struct is_nothrow_callable; // not defined template <class Fn, class... ArgTypes, class R> struct is_nothrow_callable<Fn(ArgTypes...), R>; | (2) | (since C++17) |
Fn is callable with the arguments ArgTypes... and the result would be convertible to R. Formally, determines whether INVOKE(declval<Fn>(), declval<ArgTypes>()..., R) is well formed when treated as an unevaluated operand.Fn is callable with the arguments ArgTypes... and the result would be convertible to R (same as (1)), and that such call is known not to throw any exceptions.Fn, R, and all types in ArgTypes can be any complete type, array of unknown bound, or (cv-qualified) void.
| Defined in header
<type_traits> | ||
|---|---|---|
template <class T, class R = void> constexpr bool is_callable_v = std::is_callable<T, R>::value; | (1) | (since C++17) |
template <class T, class R = void> constexpr bool is_nothrow_callable_v = std::is_nothrow_callable<T, R>::value; | (2) | (since C++17) |
| value
[static]
| true if INVOKE(declval<Fn>(), declval<ArgTypes>()..., R) is well formed when treated as an unevaluated operand , false otherwise (public static member constant) |
| operator bool | converts the object to bool, returns value (public member function) |
| operator()
(C++14)
| returns value (public member function) |
| Type | Definition |
|---|---|
value_type | bool |
type | std::integral_constant<bool, value> |
Version (1) of this trait may be implemented in terms of std::is_convertible and std::result_of.
| (C++17)
| invokes any Callable object with given arguments (function template) |
| (C++11)
| deduces the return type of a function call expression (class template) |
| (C++11)
| obtains a reference to its argument for use in unevaluated context (function template) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/types/is_callable