Template mixin enum stringof
Lemonfiend via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Wed Dec 10 05:58:20 PST 2014
On Wednesday, 10 December 2014 at 12:57:16 UTC, ketmar via
Digitalmars-d-learn wrote:
> On Wed, 10 Dec 2014 12:35:44 +0000
> Lemonfiend via Digitalmars-d-learn
> <digitalmars-d-learn at puremagic.com>
> wrote:
>
>> On Wednesday, 10 December 2014 at 12:08:34 UTC, ketmar via
>> Digitalmars-d-learn wrote:
>> > On Wed, 10 Dec 2014 11:52:11 +0000
>> > Lemonfiend via Digitalmars-d-learn
>> > <digitalmars-d-learn at puremagic.com>
>> > wrote:
>> >
>> >> Consider the following:
>> >>
>> >> ---
>> >> enum Foo { BAR, }
>> >>
>> >> mixin template S(string s_)
>> >> {
>> >> enum s = s_;
>> >> }
>> >>
>> >> void main()
>> >> {
>> >> mixin S!(Foo.BAR.stringof); // Error: identifier
>> >> 'stringof' of 'Foo.BAR.stringof' is not defined
>> >>
>> >> enum e = Foo.BAR.stringof;
>> >> mixin S!(e); // works fine
>> >> }
>> >> ---
>> >>
>> >> Why doesn't the first work? And is there an alternative to
>> >> the second version?
>> >
>> > mixin S!((Foo.BAR).stringof);
>> >
>> > sorry, don't remember the parsing rule for this.
>>
>> Wow, I didn't even consider that.. Thanks!
> also, you can use this:
>
> import std.conv : to;
> ...
> mixin S!(to!string(Foo.BAR));
>
> people tend to forget that many `to!` variants are usable in
> CTFE.
Seems like I'd want to move the converting-to-string
functionality to within the template mixin then, something like:
---
mixin template S(T, T t) if (is(T == enum))
{
//import std.traits;
//enum s = fullyQualifiedName!(t); // unfortunately this results
in "t"
import std.conv: to;
enum s = to!string(t); // this works
}
mixin S!(Foo, Foo.BAR);
---
But passing an enum as parameter seems to be somewhat annoying.
If I leave off the first Foo, then it complains about no-matching
template for int parameter.
!(Foo, Foo.BAR) seems kinda redundant..
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