Can you cache a virtual function lookup in C++?

Question

Say I have a virtual function call foo() on an abstract base class pointer, mypointer->foo(). When my app starts up, based on the contents of a file, it chooses to instantiate a

Answer 1

So assuming that this is a fundamental issue you want to solve (to avoid premature optimization arguments), and ignoring platform and compiler specific hackery, you can do one of two things, at opposite ends of complexity:

1. Provide a function as part of the .dll that internally simply calls the right member function directly. You pay the cost of an indirect jump, but at least you don't pay the cost of a vtable lookup. Your mileage may vary, but on certain platforms, you can optimize the indirect function call.
2. Restructure your application such that instead of calling a member function per instance, you call a single function that takes a collection of instances. Mike Acton has a wonderful post (with a particular platform and application type bent) on why and how you should do this.