Hi,
Last week's TWiD had a tip that didn't make sense:
http://dpldocs.info/this-week-in-d/Blog.Posted_2019_05_20.html#tip-of-the-week

template Locals(int i) {
    alias Whatever = int;
}

static foreach(i; [1, 2, 3]) {
   Locals!i.Whatever;
}

The body is just `int;`. Not sure how to reach Adam. What was intended?

On Tuesday, 28 May 2019 at 13:43:45 UTC, Nick Treleaven wrote:
> Hi,
> Last week's TWiD had a tip that didn't make sense:
> http://dpldocs.info/this-week-in-d/Blog.Posted_2019_05_20.html#tip-of-the-week
>
> template Locals(int i) {
>     alias Whatever = int;
> }
>
> static foreach(i; [1, 2, 3]) {
>    Locals!i.Whatever;
> }

> The body is just `int;`. Not sure how to reach Adam. What was intended?

Yes, intended, but also incomplete. The idea there is to use the template as a namespace for whatever local stuff you had. (I adapted this from a reflection thing where Whatever would have been an alias to a member type, and then in simplifying to get to just the new idea - and in a rush to type it up that day - I removed like all the context).

So it might actually be more like (still an incomplete example but more complete):

void test(T)() {
  template Locals(int i) {
     static if(is(typeof(__traits(getMember, T, __traits(allMembers, T)[i])) Ret == return))
       alias ReturnValue = Ret;
  }

  static foreach(idx, t; __traits(allMembers, T)) {
     mixin("auto " ~ t ~ "() { return Locals!idx.ReturnValue.init; }");
  }
}


So now the Locals template wraps a bunch of aliases so we can refer to them more succinctly later.

A regular alias defined inside that static foreach would end up being duplicated in future iterations. Putting the extra {} around it would mean the mixed in function would not be visible outside.

so the Locals template is just a collection of convenience aliases in a namespace.

Ok, thanks for explaining. Nice idea.