Generating an enum from a tuple of Types?
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.
Re: Generating an enum from a tuple of Types?
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
Re: Generating an enum from a tuple of Types?
If one wants to generate code with new identifiers, usage of string mixins is pretty much unavoidable.
Re: Generating an enum from a tuple of Types?
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/mtkzbwfgwsstndxbe...@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
Re: Generating an enum from a tuple of Types?
Am Sat, 25 Jan 2014 18:55:54 +0100 schrieb Artur Skawina art.08...@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/mtkzbwfgwsstndxbe...@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.
