DIP 1030--Named Arguments--Community Review Round 1 Discussion

[Timon Gehr]

On 10.02.20 20:46, Adam D. Ruppe wrote:
> On Monday, 10 February 2020 at 19:38:34 UTC, Manu wrote:
>> If we must mirror
>> the argument names and default arguments, you must fall back into 
>> string mixin territory
> 
> It is super simple. Consider this example:
> 
> ---
> int foo(string s = null, int a = 12) {
>          return a + 12;
> }
> template wrapWithPrint(alias fn) {
>          static if(is(typeof(fn) P == __parameters))
>          auto wrapWithPrint(P params) {
>                  import std.stdio;
>                  writeln(params);
>                  auto ret = fn(params);
>                  writeln("returned: ", ret);
>                  return ret;
>          }
>          else static assert(0);
> }
> void main() {
>          wrapWithPrint!foo();
>          wrapWithPrint!foo("cool");
>          wrapWithPrint!foo("cool", 20);
> }
> ---
> 
> Default values and param names are included in the __parameters thing 
> and just works if you use it directly.
> 
> I saw people overcomplicating this just a few hours ago too which is why 
> I have this example ready. There's plenty of techniques to do this 
> though I guess they aren't well known.

What if fn is a template?