How exactly does Tuple work?

[Jan Hönig]

On Sunday, 8 November 2020 at 13:10:33 UTC, Adam D. Ruppe wrote:
> On Sunday, 8 November 2020 at 10:03:46 UTC, Jan Hönig wrote:
>> Is there some recourse, which explains the `alias <something> 
>> this`?
>
> If your object is used in a way that doesn't compile, the 
> compiler will change `obj` to `obj.whatever_alias_this_is` and 
> try again.
>
> So say you have
>
> struct S {
>     int a;
>     alias a this;
> }
>
> S obj;
>
> obj += 5;
>
>
> It will see that obj +=5 doesn't compile on its own, but it has 
> alias a this so it changes `obj` to `obj.a` and tries again.
>
> So `obj.a += 5;` is the end result.

So it's like inheritance resolved at compile time. It's 
inheritance with virtual member functions without overhead.
I am guessing only one alias works.

And we use this, because struct can't do inheritance and 
interface is abstract.