I have following architecture

class A_Base {
    virtual foo() { } }

class A_Derived : public A_Base  {
    foo () { } }

class B_Base : A_Base {
    bar() { foo() } 
}

class B_Derived : public B_Base, A_Derived {
}

int main () {
    B_base var = B_Derived();

    var.bar(); // calls foo() from class A_Base and not A_Derived  
}

B_base has to heritate from A_base.

How can I make that when calling var.bar(), bar is called from A_Derived and not A_Base