Multiple Inheritance : Overriding same named functions in derived.

Technique for overriding same named functions in Base classes in a multiple inheritance: ( See : Item 43 in Effective C++ , see also, Exceptional C++ )

#include < iostream >
using namespace std;

class Base1{
    public:
    virtual int func(){ cout << "base1::func" << endl; }
};

class Base2{
    public:
    virtual int func(){ cout << "base2::func" << endl; }
};

class Der : public Base1, public Base2
{
    public:
    // overrides both Base1, and Base func
    virtual int func() { cout << "der::func" << endl; }
};

/** Using auxillary classes  */
class AuxBase1: public Base1{
    public:
        virtual int base1_func() = 0;
        virtual int func() {return base1_func(); }
};
class AuxBase2: public Base2{
    public:
        virtual int base2_func() = 0;
        virtual int func() {return base2_func(); }
};

class Der2 : public AuxBase1, public AuxBase2
{
    int base1_func() { cout << __func__ << endl; }
    int base2_func() { cout << __func__ << endl; }
    
};

int main()
{
    Der *pd = new Der();
    Base1 *p1 = pd;
    Base2 *p2 = pd;
    p1->func();
    p2->func();
    pd->func();

    Der2 *pd2 = new Der2();
    p1 = pd2;
    p2 = pd2;
    p1->func();
    p2->func();
}

Output :

der::func
der::func
der::func
base1_func
base2_func