Is it proper to use a default constructor with polymorphism?

Question

I basically have something like this:

class CGlToolBase
{
public:
    CGlToolBase(void)
    {

    }
    virtual void OnMouseDown(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnMouseMove(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnMouseUp(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnKeyDown(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnLDoubleClick(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    ~CGlToolBase(void);
};

class CGlToolSelect : public CGlToolBase
{
   bool selected;
public:
    CGlToolSelect(void)
    {
     selected = false;
    }
    virtual void OnMouseDown(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnMouseMove(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnMouseUp(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnKeyDown(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    virtual void OnLDoubleClick(CGlEngine &glEngine, WPARAM wParam, LPARAM lParam);
    ~CGlToolSelect(void);
};

In my select tool I set selected to false. Is this the correct way to do it if I do something like this:

CGlToolBase *tool = new CGlToolSelect;

Thanks

Answer 1

That's perfectly legal and acceptable.

However, some notes:

Your destructor should be virtual. If any class has virtual methods (abstract or not), you should have a public virtual (abstract?) destructor (so delete calls the children destructors) or a protected non-virtual destructor (which prevents the superclass from being deleted as a superclass (it must be deleted as a subclass, thus calling the appropriate destructor)).

You may want to use initializers to set selected in the constructor:

CGlToolSelect() :
    selected(false)
{
}