super-interfaces

[Chris Nicholson-Sauls]

Bill Baxter wrote:
> I think this may be a bug with super-interfaces.
> It's telling me that something is not an override, when, in fact, it is.
> 
> Here's the setup:
> 
> interface Fruit
> {
>    ...  // some methods
> }
> interface Vehicle
> {
>    void drive_around();
>    ...  // some other methods
> }
> interface MobileFruit : Fruit, Vehicle
> {
>    // nothing here, should inherit from superinterfaces
> }
> 
> class BaseFruit : Fruit
> {
>    // implement (some of) Fruit's methods here
> }
> 
> class MobileFruitGundam : BaseFruit, MobileFruit
> {
>    // implement what's not in BaseFruit already
> 
>    override void drive_around() {..} // from Vehicle
> }
> 
> The last part doesn't work.  It tells me that drive_around is not an 
> override.  But it works if I don't tag it with 'override'.
> 
> Is that a bug?
> 
> --bb

I don't think it is.  As I understand it, 'override' only masks a virtual function 
implementation or 'abstract' placeholder.  Interfaces do not provide implementations nor 
placeholders, only a contract requiring certain signatures exist.  The main use of 
'override' is to catch non-back-compatible API changes.

-- Chris Nicholson-Sauls