virtual overhead

[hendrixj]

I started out with a class that need some functions to be virtual for the usual reasons. As the code was scrubbed, that reason went away. It led me to a question: If a class (that does not inherit from anyone, so it is a base class) uses the virtual keyword for a function that never gets overridden in a derived class (since there are no derived classes), should I expect the "virtual" keyword to force a vtable lookup when the function is called?
Put another way, should I expect the compiler to recognize that a vtable for is not necessary and do the binding directly?

John

[Danny]

Sadly, the answer is yes, but only if you call a member function through a pointer or a reference. A call to a member function via an object is always resolved statically.
Clever compilers and compilers that do whole program analysis are able to optimize away vtable lookup when the function called through a pointer/reference can be resolved statically but don't count on that. So the real question is: does your code call the member functions through pointers or references?
Notice that in any event, virtual implies a vtable per class so the space overhead is inevitable.