Multiple same class instances in single parent class

Question

I am trying to have multiple instances of the same class in a parent class. Each with their own constructor arguments.

I have tried this, but not sure how to fix this. Any help would be greatly appreciated.

Base.h

class Base
{
    public:
    Base(int a, int b);
};

Parent.h

#include "Base.h"

class Base_A :Base{};
class Base_B :Base{};

class Parent : Base_A, Base_B 
{
    public:
    Parent (int a1, int a2, int b1, int b2);
}

Parent.cpp

Parent::Parent (int a1, int a2, int b1, int b2) :Base_A(a1,a2), Base_B(b1,b2)
{
    //....
}

When compiling I get the following error:

no instance of constructor "Base_A::Base_A" matches the argument list -- argument types are: (int, int)
no instance of constructor "Base_B::Base_B" matches the argument list -- argument types are: (int, int)

Answer 1

You don't have constructors for the Base_A class and Base_B class (which takes two integers as arguments). This is exactly what the compiler is showing us with an error. So all what we need to do is define the constructor.

class Base_A : Base 
{
public:
    Base_A(int a, int b) : Base(a, b) {}
};

class Base_B : Base 
{
public:
    Base_B(int a, int b) : Base(a, b) {}
};

Note: You might run into the diamond problem. This is because both Base_A and Base_B are inherited from the class Base.