Question

I have a base class Shape and some other derived classes like Circle, Rectangle and so on. I would like to pass two objects to a function getDistance(object1, object2) to calculate the distance between the two objects.

My question is, how should this function be declared and implemented? Do you think I should use template since I might pass two objects from two different classes? If so, how would the template look like?

Any help is appreciated

Answer 1

Usually you would use a pure virtual on your base class. You already have inheritance from Shape, so templates are overkill for this problem.

Add a virtual GetPosition() to your base Shape class and make getDistance() take two Shape pointers (or references). For example:

class Shape
{
public:
    ~virtual Shape() {}  // Make sure you have a virtual destructor on base

    // Assuming you have a Position struct/class
    virtual Position GetPosition() const = 0;
};

class Circle : public Shape
{
public:
    virtual Position GetPosition() const;  // Implemented elsewhere
};

class Rectangle : public Shape
{
public:
    virtual Position GetPosition() const;  // Implemented elsewhere
};

float getDistance(const Shape& one, const Shape& Two)
{
    // Calculate distance here by calling one.GetPosition() etc
}

// And to use it...
Circle circle;
Rectangle rectangle;
getDistance(circle, rectangle);

EDIT: Pawel Zubrycki is correct – added virtual destructor on base class for good measure. 😉