Hi, would the response to this question : http://stackoverflow.com/questions/757684/enum-inheritance be the same for D?

I have these two enums:
enum first : string{
 a="a",
 b="b"
}

enum second : string{
 a=first.a,
 b=first.b,
 c="c"
}

Is there a way to make this cleaner? I don't mind having something like
second.firstchar.a
with firstchar  beeing a "first" enum.

To do that I would need to tell the enum that it can also use the type "first" because in the end, that is a string too...

On 2012-07-26 13:40, maarten van damme wrote:
> Hi, would the response to this question :
> http://stackoverflow.com/questions/757684/enum-inheritance be the same
> for D?
>
> I have these two enums:
> enum first : string{
>   a="a",
>   b="b"
> }
>
> enum second : string{
>   a=first.a,
>   b=first.b,
>   c="c"
> }
>
> Is there a way to make this cleaner? I don't mind having something like
> second.firstchar.a
> with firstchar  beeing a "first" enum.
>
> To do that I would need to tell the enum that it can also use the type
> "first" because in the end, that is a string too...

I'm pretty sure it's possible to do with some meta programming magic.

-- 
/Jacob Carlborg

maarten van damme:

> enum first : string{
>  a="a",
>  b="b"
> }
>
> enum second : string{
>  a=first.a,
>  b=first.b,
>  c="c"
> }
>
> Is there a way to make this cleaner?

By convention in D enum names start with an upper case.

I have tried this, partially derived by Simen Kjaeraas code (with T.stringof), but isn't D supporting mixins inside enums?


string EnumInh(T)() if (is(T == enum)) {
    string result;
    foreach (e; __traits(allMembers, T))
        result ~= e ~ " = " ~ T.stringof ~"." ~ e ~ ",\n";
    return result;
}

enum First : string {
    a = "a",
    b = "b"
}

enum Second : string {
    mixin(EnumInh!First),
    c = "c"
}

void main() {}

Bye,
bearophile

On Thu, 26 Jul 2012 15:07:56 +0200, bearophile <bearophileHUGS@lycos.com> wrote:

> but isn't D supporting mixins inside enums?

Nope. "The text contents of the string must be compilable as a valid StatementList, and is compiled as such."

And enums don't allow statements in their body.

-- 
Simen