[fpc-devel] Question on interface inheritance...

[Martin Frb]

On 01/02/2026 16:34, Mattias Gaertner via fpc-devel wrote:
>
> On 2/1/26 15:51, Martin Frb via fpc-devel wrote:
>>
>> Or do you mean, the act of reintroduction, rather than the keyword?
>
> I think the compiler should not allow reintroducing in interfaces.
>
> In Delphi you get the same problem, stopping with
>
> TIntfBarBase.GetFoo is not implemented
>

Ok, lets see what other think / it wont help for now either, since it 
wont work with the current compiler.


But I do think that (other than the work for the compiler devs) it would 
be a neat feature.

Though, probably only if the reintroduced version returns a subclass of 
the original

IFaceBase
    GetFoo: TFooBase;

IFace(IFaceBase)
    GetFoo: TFoo;

Since TFoo inherits from TFooBase the new interface still 100% fulfils 
the contract of the base.

Technically the interfaces still work even if the types are non 
compatible (since the method of the base interface still exists in the 
inherited, it only can't be accessed directly)