Can I get polymorphic behavior without using virtual functions?

Question

Because of my device I can\'t use virtual functions. Suppose I have:

class Base
{
    void doSomething() { }
};

class Derived : public Base
{
    void doSom         


        

Answer 1

You can make your own vtable, I suppose. I'd just be a struct containing your "virtual" function pointers as part of Base, and have code to set up the vtable.

This is kind of a gross solution -- it's the C++ compiler's job to handle this feature.

But here goes:

#include 

class Base
{
protected:
    struct vt {
        void (*vDoSomething)(void);
    } vt;
private:
    void doSomethingImpl(void) { std::cout << "Base doSomething" << std::endl; }
public:
    void doSomething(void) { (vt.vDoSomething)();}
    Base() : vt() { vt.vDoSomething = (void(*)(void)) &Base::doSomethingImpl;}
};

class Derived : public Base
{
public:
    void doSomething(void) { std::cout << "Derived doSomething" << std::endl; }
    Derived() : Base() { vt.vDoSomething = (void(*)(void)) &Derived::doSomething;}
};