Considering the fact that a pointer to a function returning another pointer to another function is the mechanism used in C to introduce some runtime polymorphism/callbacks, What is the equivalent way to implement this in C++ while improving locality and lower the cost about pointers and indirections ?
For example this syntactic sugar can help but I'm not really interested in this, altough it's a nice way to do things in a C++ way instead of a more C-ish typedef, I'm more interested in improving locality while trying to reduce the use of explicit pointers at runtime.
The real reason as to why people use function pointers in C to emulate polymorphism is not performance but the fact that C neither supports real polymorphism nor templates. These are two alternatives you have in C++. All three approaches are compared in this thread.
Note that even though calling a function pointer does not require the additional vtable lookup that virtual function calls do, calling virtual functions and function pointers both suffer from the same major performance problem: Branch prediction in both cases is not as reliable and you tend to end up with more pipeline flushes.