Hi,
I have two questions about interface usage.
1. How interfaces are to handle when casting?
Theoretically it should be safe to do this:
TObservable = class
public
procedure Register( obsv: IObserver );
private
procedure NotifyObservers(param: TParameter);
fObservers: TFPObjectList;
end;
procedure TObservable.Register( obsv: IObserver );
begin
fObservers.add(TObject(obsv));
end;
When using a cast from an interface to an object the compiler warns
about the class types "TObject" and "IObserver" not being related.
Since an implementor of in interface always will be a class type and any
class type at least inherits from TObject, I assume it is okay?
Is there a better method of handling this case?
2. Will an interface and a class with the same signature but not
explicitely implementing this interface be runtime-compatible and
interchangably usable?
Smth. like this:
IObserver = Interface
procedure Notify( param: TParameter );
end;
TObserver = class
public
procedure Notify( param: TParameter ); virtual; abstract;
end;
Is it legal to use one or the other when e.g. handing over an observer
to a method having an IObserver as argument?
TIA,
Marc
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