Question

Do the methods of a member variable have access to other private member variables within the same class? I have in mind a functor member variable.

Can a pointer to a private member variable be dereferenced and assigned to, outside of the class? What about in the method of another member variable?

Maybe something like

class A
{
 someClass a,b;

 A(){a(&b);}
}

Answer 1

Whenever you are calling the method of a member variable, unless its type is the class being defined, you won’t have access to private member variables.

If you give access (somehow) to a pointer to a member variable, without precising that it is “const”, yes, it can be dereferenced and assigned to. The same assertion is still true for the methods of other member variables.

AFTER QUESTION HAS BEEN EDITED :
In your example, you are calling a method (through member variable “a”), providing a pointer to private member variable “b”. You are accessing these two private member variables in A, which is perfectly correct c++.