Interfaces, traits, concepts, and my idea for a DIP

[Tofu Ninja via Digitalmars-d]

On Wednesday, 29 July 2015 at 14:51:52 UTC, Atila Neves wrote:
> On Wednesday, 29 July 2015 at 08:25:04 UTC, Roland Hadinger 
> wrote:
>> On Tuesday, 28 July 2015 at 12:49:17 UTC, Atila Neves wrote:
>>> So... instead of having traits / concepts, what I wanted from 
>>> D is to be able to do this:
>>>
>>> struct MyRange: isInputRange { ... }
>>
>> +1
>>
>>> or
>>>
>>> struct MyRange: static isInputRange { ... } // that way 
>>> classes could do this too
>>
>> What about this instead:
>>
>>     @satisfies(isInputRange) struct MyRange { ... }
>>
>> which is not as terse, but maybe less confusing, because 
>> intuitively ':' could be mistaken to mean 'extends'.
>>
>> 'static' has too many meanings already for my taste. I really 
>> don't like it when frequently used keywords are reused to mean 
>> different things in slightly different places.
>
> That looks nice, but who's going to check it? UDAs have to be 
> reflected on to well, do anything. At least a template mixin 
> will cause a static assert to fail.
>
> Atila

If you write:

@satisfies!(isInputRange, MyRange) struct MyRange { ... }

the UDA can check it self, it really works as expected. Which is 
why I suggested a way to get whatever the UDA is attached to 
automatically in my other post.