Covariant problem

[Zarathustra]

Steven Schveighoffer Wrote:

> "Zarathustra" wrote
> > error:
> > function basis.CPolygon2d.getPoints of type CPoint2d[]() overrides but is 
> > not covariant with basis.CPolygon3d.getPoints of type CPoint3d[]()
> >
> > I don't know how to fix this problem. What does 'covariant' mean?
> 
> Covariant means that the override returns something that can be implicitly 
> casted to the base version.
> 
> So the error looks like the base class function getPoints returns type 
> CPoint3d[], but the derived class is returning CPoint2d[].  In order for 
> this to work, CPoint2d[] must be implicitly castable to CPoint3d[], which 
> probably isn't true.
> 
> In order to diagnose the problem exactly, we would have to see code.  At 
> least the class hierarchy.
> 
> -Steve 
> 
> 

Ok, thanks. I understand it now.
CPoint2d class is inherited by CPoint3d. Both classes have same named functions with this difference that one return CPoint2d object and second CPoin3d object. Is possible to extort to call correct function (not from parent class). It's strange, because CPoint2d can be casted to CPoint3d but not inversely.