Background:

I intend to use builder pattern to create a branch of concreate classes whose parent classes are the same. Since all the said concreate classes to be instantiated all need a same setting method, say

void set_mgr(Mgr&);,

so it seems that there should be a member variable(whose type is Mgr*) in the pure abstract class. And a copy constructor is needed in the pure abstract class.

I have carefully read this question on the stackoverflow. There is even an example to show it’s legal to implenment a copy constructor for a pure abstract class, but the code snippet could not be compiled at all.