Is it possible to generate a enum from a tuple of types without string mixins?
------------
struct S(Types...)
{
    enum Tag
    {
        //?
    }
}
------------

where the tag enum should have Types.length members. The exact names of the enum members don't matter and could be numbered, for example: Tag._1, Tag._2, ...

This is what I have right now, using string mixins: http://dpaste.dzfl.pl/536e0be9

It implements a simple C-like tagged union in a generic way, so stuff like this is possible:

-------------------------------------------
alias Value = TaggedUnion!(int, string);
auto val = Value("Hello");
auto vals = val.get!string();
val.set(0);
final switch(val.tag)
{
    case Value.tagType!int:
        break;
    case Value.tagType!string:
        break;
}
-------------------------------------------

It's basically std.variant Algebraic with less features, but it should be much faster as it doesn't use TypeInfo.

On Saturday, 25 January 2014 at 15:38:39 UTC, Johannes Pfau wrote:
> Is it possible to generate a enum from a tuple of types without string
> mixins?
> ------------
> struct S(Types...)
> {
>     enum Tag
>     {
>         //?
>     }
> }
> ------------



Without mixins altogether... dunno. But nothing stops you from making a eponymous template :)

http://dpaste.dzfl.pl/0af9dd7e

If one wants to generate code with new identifiers, usage of string mixins is pretty much unavoidable.

On 01/25/14 16:38, Johannes Pfau wrote:
> Is it possible to generate a enum from a tuple of types without string mixins?
> ------------
> struct S(Types...)
> {
>     enum Tag
>     {
>         //?
>     }
> }
> ------------
> 
> where the tag enum should have Types.length members. The exact names of the enum members don't matter and could be numbered, for example: Tag._1, Tag._2, ...

Well, if you don't need names then just use the index directly.

Eg, see 'DiscUnion.type' in

http://forum.dlang.org/thread/mtkzbwfgwsstndxbesgy@forum.dlang.org#post-mailman.555.1377703234.1719.digitalmars-d-learn:40puremagic.com

(A newer compiler may allow for that offset-of calculation at CT)

artur

Am Sat, 25 Jan 2014 18:55:54 +0100
schrieb Artur Skawina <art.08.09@gmail.com>:

> 
> Well, if you don't need names then just use the index directly.
> 
> Eg, see 'DiscUnion.type' in
> 
> http://forum.dlang.org/thread/mtkzbwfgwsstndxbesgy@forum.dlang.org#post-mailman.555.1377703234.1719.digitalmars-d-learn:40puremagic.com
> 
> (A newer compiler may allow for that offset-of calculation at CT)
> 
> artur

Thanks for all the answers, I guess I'll keep the string mixin.
I don't really need the names but I need the enum to support final
switch.