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

All answers are dealing with the most simple scenario, where calling a virtual method only requires getting the address of the actual method to call. In the general case, when multiple and virtual inheritance come into play, calling a virtual method requires shifting the this pointer.

The method dispatch mechanism can be implemented in more than one way, but it is common to find that the entry in the virtual table is not the actual method to call, but rather some intermediate 'trampoline' code inserted by the compiler that relocates the this pointer prior to calling the actual method.

When the dispatch is the simplest, just an extra pointer redirection, then trying to optimize it does not make sense. When the problem is more complex, then any solution will be compiler dependent and hackerish. Moreover, you do not even know in what scenario you are: if the objects are loaded from dlls then you don't really know whether the actual instance returned belongs to a simple linear inheritance hierarchy or a more complex scenario.