20 General utilities library [utilities]

20.8 Function objects [function.objects]

20.8.11 Polymorphic function wrappers [func.wrap]

20.8.11.2 Class template function [func.wrap.func]

20.8.11.2.4 function invocation [func.wrap.func.inv]

R operator()(ArgTypes... args) const

Effects: INVOKE(f, std::forward<ArgTypes>(args)..., R) ([func.require]), where f is the target object ([func.def]) of *this.

Returns: Nothing if R is void, otherwise the return value of INVOKE(f, std::forward<ArgTypes>(args)..., R).

Throws: bad_function_call if !*this; otherwise, any exception thrown by the wrapped callable object.