Storing classes in boost::variant - c++

Question

Someone recommended me to use boost::variant as shape variable to store different types of shapes in it. But, when implemented boost::variant to my code, I got an error while compiling. Error says: 'Shape': base class undefined and more errors.
Here is my code (Object.h):
using Shape = boost::variant<Rectangle, Circle>;
enum Shape_Type
{
RECTANGLE,
CIRCLE
};
struct Position
{
float x, y;
Position(float position_x, float position_y)
{
x = position_x;
y = position_y;
}
};
class Object : private Shape
{
private:
std::string name;
public:
Object() = default;
Object(std::string name, Rectangle rectangle) : name(name), Shape(rectangle)
{
}
Object(std::string name, Circle circle) : name(name), Shape(circle)
{
}
void setPosition(float, float);
void setAngle(float);
Shape* getShape()
{
Shape* shape = this;
return shape;
}
Position getPosition();
const std::string* getName()
{
return &name;
}
};
class Rectangle
{
private:
sf::RectangleShape rectangleshape;
public:
Rectangle() = default;
Rectangle(float width, float height)
: rectangleshape(sf::RectangleShape(sf::Vector2f(width, height)))
{
}
void setPosition(float position_x, float position_y)
{
rectangleshape.setPosition(position_x, position_y);
}
void setAngle(float angle)
{
rectangleshape.setRotation(angle);
}
sf::RectangleShape* getRectangleShape()
{
return &rectangleshape;
}
Position getPosition()
{
return Position(rectangleshape.getPosition().x,
rectangleshape.getPosition().y);
}
};
class Circle
{
private:
sf::CircleShape circleshape;
public:
Circle() = default;
Circle(std::string name, float radius)
: circleshape(sf::CircleShape(radius))
{
}
void setPosition(float position_x, float position_y)
{
circleshape.setPosition(position_x, position_y);
}
void setAngle(float angle)
{
circleshape.setRotation(angle);
}
sf::CircleShape* getCircleShape()
{
return &circleshape;
}
Position getPosition()
{
return Position(circleshape.getPosition().x,
circleshape.getPosition().y);
}
};
And btw is getShape() function good?

Answer 1

Variants are used for static polymorphism, so you don't need the base class at all (that's dynamic - or virtual - polymorphism).
The members in a variant typically do not share a common base class, so you wouldn't have the getShape function, or you'd need to template it:
template <typename T>
T const& getShape() const { return boost::get<T>(_shape); }