> If you need to keep that pointer in a collection, or in a class member, or pass as a function argument, “auto” won’t work. Trivially solved with decltype, no

> If you need to keep that pointer in a collection, or in a class member, or pass as a function argument, “auto” won’t work. Trivially solved with decltype, no need to remember anything. decltype(std::mem_fn(&Foo::Whatever)) Typedef it if you want. > And std::function introduce some performance overhead. It's the same performance as a virtual function call. Pretty much the same as a function pointer invoke.