Wishlist proposal, documenting fn arg as in or out or mod

[Cecil Ward]

On Wednesday, 21 June 2023 at 00:55:40 UTC, Richard (Rikki) 
Andrew Cattermole wrote:
> On 21/06/2023 3:01 AM, Cecil Ward wrote:
>> I would love to be able to document my arguments
>
> If you want a way to do it without compiler backed you can use 
> UDA's:
>
> ```d
> void main() {
>     func(2);
> }
>
> enum MyThing;
>
> void func(@MyThing int x) {
> }
> ```

Wow, I didn’t know that kind of tech was extensible like that. I 
really need the checking that the compiler does though, on in for 
example, making it const, and out presumably being either ref. 
(Or input-output passing of registers, seeing as having to have a 
pointer to a one machine word-sized value, say, that was in a 
register only one nanosec ago, is a bit mad. One hopes that the 
compilers might have a small size limit and switch to copy-by-ref 
only if args width exceeds that size.)

That could give me a way of starting full documentation earlier 
though.