While looking at the implementation of std::reference_wrapper
here
The constructors and operators are obvious to me but I didn't understand this part
template< class... ArgTypes >
typename std::result_of<T&(ArgTypes&&...)>::type
operator() ( ArgTypes&&... args ) const {
return std::invoke(get(), std::forward<ArgTypes>(args)...);
}
Could someone simplify it for me ... would be appreciated
Edit: and would be great to give useful example for operator() of std::reference_wrapper
This defines the operator() member function, which is applicable for an std::reference_wrapper wrapping a reference to a Callable. The purpose of it is to call the underlying Callable.
class ... Args is to make it generic in terms of the parameters that can be passed to the underlying Callable.typename std::result_of<T&(ArgTypes&&...)>::type partinvoke call as a general-purpose way of calling the Callable, which works irrespective of what type of Callable it is (Functor, function pointer, member function pointer etc).std::forward in passing the argument list to achieve perfect forwarding - so for example lvalue and rvalues passed in to the original call retain their l/rvalue-ness in the underlying call.
operator()to the referee Functor.