Question

I always think of having to use pointers for polymorphism. Using the canonical example:

DrawEngine::render(Shape *shape)
{
    shape->draw();
    shape->visible(true);
}

And passing in pointer to various Shape derived classes. Does it work the same with references?

DrawEngine::render(Shape &shape)
{
     shape.draw();
     shape.visible(true);
}

Is it even valid to do:

engine.render(myTriangle); // myTriangle instance of class derived from Shape

If this works, are there any differences between the two cases? I tried to find information in Stroustrup, but I found nothing.

I reopened this because I wanted to explore just a tad more.

So at least one difference is dynamic_cast. For me, polymorphism includes the use of dynamic_cast.

Can I go

Rhomboid & r = dynamic_cast<Rhomboid &>(shape);

What happens if the cast fails? Is this any different?

Rhomboid * r = dynamic_cast<Rhomboid*>(&shape);

Answer 1

With regard to polymorphism, references work just like pointers.