D should have a root interface

downs default_357-line at yahoo.de
Mon Jul 28 22:13:27 PDT 2008


Frank Benoit wrote:
> Robert Fraser schrieb:
>> Frank Benoit Wrote:
>>
>>> // user lib
>>> interface List{
>>>     void add(Object);
>>> }
>>> interface ArrayList : List{
>>>     void add(Object){}
>>> }
>>>
>>> // calling code
>>> List list = ...
>>> IFile file = ... // interface type
>>> list.add( file ); // compile error
>>> list.add( cast(Object) file );
>>>
>>> This makes problems when one want to add() an interface instance. A
>>> cast to Object is necessary. This is so ugly.
>>>
>>> If there would be at least an empty root interface for all D
>>> interfaces, this can be used for method signatures.
>>>
>>> // D runtime and used by compiler
>>> interface IObject {
>>> }
>>>
>>> // user lib
>>> interface List{
>>>     void add(Object);
>>>     void add(IObject);
>>> }
>>> interface ArrayList : List{
>>>     void add(Object){ ... }
>>>     void add(IObject io){ add(cast(Object)io); }
>>> }
>>>
>>> This would not break any code and helps to make the calling code less
>>> casty.
>>
>> Or, you know, just make all instances of interfaces that don't extend
>> IUnknown implicitly castable to object.
> 
> yes yes yes yes!
> 
yes!!

please :(

:ahem: strong vote in favor from me.



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