Calling an overridden function from a base class?

Question

My question will probably be best explained by an example.

For example, I have 2 classes: A base class and a derived class:

class baseClass
{
public:
    baseClass()
    {
        foo();
    }
    virtual bool foo() { printf("baseClass"); return false;}

};

class derivedClass : public baseClass
{
public:
    bool foo()
    {
        printf("derivedClass");
        return true;
    }

};

When I create an instance of derivedClass, the constructor in baseClass will be called, and foo() will be called from it's constructor. The problem is, the baseClass' constructor is calling its own foo() and no the overridden foo() that the derived class has overridden. Is there anyway to make the baseClass call the overridden function, not it's own definition of the function?

Answer 1

You should not call a virtual method from a constructor because the object has not yet been fully constructed. Essentially, the derived class doesn't exist yet, so its methods cannot be called.