[fpc-devel] suggestion: virtual method co-variance

[Flávio Etrusco]

On Tue, Oct 14, 2014 at 7:40 AM, Marco van de Voort <marcov at stack.nl> wrote:
>
> I recently had to dive a bit into C++ again, and reconnected with a feature
> I liked at first sight, the C++ covariance of virtual methods (changing the
> return type of a overriden method to a descendant of the original type).
> Googling a bit it seems that some languages(C#) also seem to allow this for
> parameters.  (not just return types)
>
> I suddenly wondered why it was never proposed or talked about  for FPC,
> since it seems such a nice feature.  Is there something particularly wrong
> with it?
>
> To a certain degree it can be emulated with generics, but that it
> requires a generic for every type, and must be prepared in the library code.
>

Actually this was kind of talked ;-)
http://lists.freepascal.org/pipermail/fpc-devel/2014-February/033394.html

Best regards,
Flávio