> On Feb 18, 2021, at 11:30 PM, Sven Barth <pascaldra...@googlemail.com> wrote:
>
> The only thing that will not work and which will continue not to work is that
> m_circle.Draw will not be called if you access the TMyShape through a
> TShape.Draw call. For that one needs to use an explicit declaration:
>
> === code begin ===
>
> type
> TMyShape = class(TShape, ICircle)
> private
> m_circle: TCircle;
> public
> procedure ICircle.Draw = Draw;
> property Circle: TCircle read m_circle implements ICircle;
> procedure Draw; override;
> end;
>
> procedure TMyShape.Draw;
> begin
> m_circle.Draw;
> end;
>
> === code end ===
So the method resolution doesn't actually change the VMT table of the class,
just the interface? That's unfortunate because being able to affect the VMT by
method resolution would open up a lot of possibilities for polymorphism using
composition. Maybe writing wrapper functions is good enough for this. Not sure,
I need to do some research into old code and explore things a bit more.
I just realized another potential problem. If we use the "default" keyword that
means there could be multiple "defaults" unless we limit the property to 1 per
class, which would kind of defeat the purpose of the feature (like the issue we
had with helpers and made multi-helpers for).
Regards,
Ryan Joseph
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