Class and Interface Fun

[Daniel Keep]

>>>> [snip]
>>>>
>>>> B inherits all the functions from A implicitly. You stil may
>>>> override any of the I interface functions if need be:
>>>>
>>>> class B : A, I
>>>> {
>>>>      override void foo() { ... }
>>>>      // int bar() is inherited from A
>>>> }
>>>>
>>>> Having B explicitly override all the base class virtual functions
>>>> and forward them to A implementation just to make compiler happy is
>>>> unintuitive and plain dumb to me.
>>>>
>>>> C# allows that and I see absolutely no reason why D doesn't.
>>>>
>>>
>>> I think you are missing somethinghere. Change the B definition from:
>>>
>>> class B : A, I
>>>
>>> to just:
>>>
>>> class B : A
>>>
>>> then interfaces become impicit.
>>
>> No, I don't:
>>
>> class B : private A, public I
>> {
>> }
>>
>>
> 
> Other example:
> 
> interface IOStream : InputStream, OutputStream
> {
> }
> 
> class A : InputStream
> {
>   // implement InputStream
> }
> 
> class B : A, IOStream
> {
>   // implement OutputStream interface *only*
> }
> 
> You can't define B like this: class B : A, OutputStream { ... } because
> this way it won't be castable to IOStream.
> 

I believe the rationale behind this is so that you can't implement an
interface "by accident."  For example, you might be implementing an
interface, miss one method, and not know because the base class
implements it.

Alternately, you might be relying on such inheritance.  Then, the base
class changes, and you're left with compile errors and wondering why it
doesn't work.

Forcing you to specify each method removes this ambiguity from the code.

That said, I could have SWORN that aliasing a method from the superclass
worked.  If this isn't a bug, it should be.

Personally, yes it is a bit tedious, but this is why we have templates
and mixins...

  -- Daniel