On 02/02/2026 22:00, Michael Van Canneyt via fpc-devel wrote:
Whether it is a good approach, there we probably differ in opinion :-)
Well, the good approach doesn't work.
interface can't have virtual/override apparently (it can but ignores).
In a class, an overridden function can actually return a subclass of
what the virtual method returned.
And well, why not, it fulfills all the need.
If that was possible in an interface too, then all would be good
IFoo = interface
function Itm: TItem; virtual;
ISubFoo = interface(IFoo)
function Itm: TSubItem; override;
ISubFoo fulfils every bit of the contract of its base.
But this does not work, so I need to look for something else.
You read my description. Ideas?
Other than just "drop the constraint" => then yes, it works, because I
have completely independent interfaces, no inheritance, just the same
name for 2 functions that have diff return types....
I can't however see, how that is better.
Copy and paste the code... That might have been the solution before
generics.
Not using interfaces at all => but this code includes (not limited but
includes) stuff that is an API for 3rd party. Really want that as an
interface.
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