[fpc-pascal] Casting descendant interface variables to base

[Andrew Hall]

On 30 Jan 11, at 22:28 , cobines wrote:

> it is now a pointer to IBaseInterface, because of implicit QueryInterface?
The reference changes because you have explicitly cast (the implementing object) to another interface.

> So, I think I can compare interface variables but first I have to
> bring them to the same interface using "as", for example to IUnknown.
Yes.  This function will confirm the two provided interfaces are implemented by the same object...

function EqIntf(a, b: IUnknown): Boolean;
begin
  Result := (a as IUnknown) = (b as IUnknown);
end;

Regards Andrew.

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