std::uses_allocator<std::function>

template< class R, class... ArgTypes, class Alloc >
struct uses_allocator<std::function<R(ArgTypes...)>, Alloc> : std::true_type { };

This specialization of std::uses_allocator informs other library components that all objects of type std::function support uses-allocator construction, even though they do not have a nested allocator_type.

Notes

std::function's allocator support was poorly specified and inconsistently implemented. Some implementations do not support uses-allocator construction at all, some provide the needed constructor overloads but ignore the supplied allocator argument, and some provide the overloads and use the supplied allocator for construction but not when the std::function is reassigned. As a result, allocator support was removed in C++17.

See also