DIP66 - Multiple alias this

[Andrei Alexandrescu]

On 9/29/20 10:08 PM, Andrei Alexandrescu wrote:
> On 9/29/20 9:42 PM, Mike wrote:
>> On Wednesday, 30 September 2020 at 01:36:59 UTC, Mike wrote:
>>
>>> So, here are a couple of proposals off the top of my head.  I imagine 
>>> someone more talented than I can think of a few more:
>>>
>>> 1.  Deprecate `alias this` for classes, and implement multiple `alias 
>>> this` for structs.  That will give users the composition feature they 
>>> need, and in addition, because structs cannot inherit, it removes the 
>>> complexity Walter spoke of.
>>>
>>> 2.  Add `opImplicit`, implicit copy constructors, or something of 
>>> that ilk.  Then users only need to forward members using D's 
>>> metaprogramming facilities.  Both uses of `alias this` are covered, 
>>> but no `alias this` is required.  `alias this` can then be deprecated 
>>> entirely.
>>>
>>> 3.  Add struct inheritance like C++.
>>
>> 4. Somehow allow structs to implement interfaces.
> 
> I'd love it if interfaces could implement methods. (All MI related 
> issues are related to state, not implementation of methods.)

BTW forgot to mention - this is from the category of removing limitations.