DIP 1020--Named Parameters--Community Review Round 2

[rikki cattermole]

On 18/09/2019 1:52 AM, jmh530 wrote:
> On Tuesday, 17 September 2019 at 13:36:59 UTC, rikki cattermole wrote:
>> [snip]
>>
>> So with signatures you essentially need a separate parameter type 
>> which says: will probably be inferred from something but can be set by 
>> the user if they really need to.
>>
>> In your above example, I suspect it will have name collisions as-is.
>>
>> [snip]
> 
> Would it help to use opDispatch? Maybe something like below (assuming 
> types are first class objects):
> 
> struct Foo(T) {
>      type opDispatch(string U)()
>          if (is(T == mixin(U))
>      {
>          return mixin(U);
>      }
> }

Yes.

But as a language feature I have no idea what first class types would do 
in D.

For example:

alias Foo(T) = T.U;

in long form:

template Foo(T) {
	alias Foo = T.U;
}

So we already have "functions" that return types+constants already.