Why typeof(template) is void?
mogu via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Tue Jul 19 22:54:41 PDT 2016
On Wednesday, 20 July 2016 at 01:50:37 UTC, Adam D. Ruppe wrote:
> On Wednesday, 20 July 2016 at 01:14:05 UTC, mogu wrote:
>> Why S's type isn't something like `S: (T) -> S`?
>
> Because S isn't a type... think of a template as being like a
> function that returns a type.
>
> int foo(int) { return 0; }
>
> There, you wouldn't expect typeof(foo) to be int, no,
> typeof(foo) is a function that returns an int.
>
> The template is the same thing - it isn't a type, it is a
> template that returns a type.
So it's a higher kinded type aka type class in Haskell. But D's
reflection cannot get enough information about template's kind.
Only a `void` given. It may be inconvenient in distinction
between an alias of template and void. The only solution AFAIK is
by string of the type property .stringof.
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