std::function<R(Args...)>::assign
Min standard notice:
Initializes the target with f. The alloc is used to allocate memory for any internal data structures that the function might use.
# Declarations
template< class F, class Alloc >
void assign( F&& f, const Alloc& alloc );
(since C++11) (removed in C++17)
# Parameters
f: callable function to initialize the target withalloc: allocator to use to allocate memory for the internal data structures
# Return value
(none)