Discussion Thread: DIP 1030--Named Arguments--Final Review

[Paul Backus]

On Wednesday, 20 May 2020 at 20:01:51 UTC, Arine wrote:
> On Wednesday, 20 May 2020 at 03:04:13 UTC, 12345swordy wrote:
>>
>> So if the implementation detail is standardized, would you 
>> still object to this?
>>
>> -Alex
>
> Both methods are terrible. A pull request that used either 
> method in phobos would be rightfully rejected today. It doesn't 
> bode well when such a destructive practice is suggested by the 
> creator of a language, and then they completely fall silent 
> from the discussion. I hope he doesn't have have the same 
> holier than though mindset as that other individual that 
> clearly stated they don't care about having any kind of 
> discussion on the subject at all. That's fine by me, it's clear 
> as night and day to me. Practicality seems to be going out the 
> door lately anyways.

Here's a method that works using existing language features and 
doesn't rely on implementation details that aren't part of the 
language spec:

int foo(int, int)
{
     static if (is(typeof(__traits(parent, {})) params == 
__parameters)) {
         mixin("alias x = ", __traits(identifier, params[0..1]), 
";");
         mixin("alias y = ", __traits(identifier, params[1..2]), 
";");
     }
     return x + y;
}

unittest
{
     assert(foo(1, 2) == 3);
}

It's pretty ugly, but the ugliness is hidden entirely inside the 
function's implementation. And the whole static if block could be 
factored out into a mixin if you wanted to re-use it in multiple 
functions.