Classes as enums in D?

[Rikki Cattermole via Digitalmars-d-learn]

On 30/11/15 8:58 PM, Andrew LaChance wrote:
> On Monday, 30 November 2015 at 07:54:49 UTC, Rikki Cattermole wrote:
>> enums don't have to be integral, but for performance reasons it is for
>> the best.
>>
>> enum Foo : string {
>>     A = "a",
>>     B = "b",
>>     C = "d",
>>     ERROR = "What are you talking about?"
>> }
>>
>> void main() {
>>     import std.stdio : writeln;
>>     Foo foo = Foo.ERROR;
>>     writeln(foo, " is: ", cast(string)foo);
>> }
>>
>> Also you are welcome in #d on Freenode (IRC) if you are interesting in
>> talking with the rest of us!
>> Btw you probably want tuples (std.typecons : tuple) to emulate those
>> values.
>
> Oh interesting.  So you are saying I could have a struct WhiteKey {...}
> and then an enum that extends WhiteKey?  You also mention Tuples, are
> you recommending the Tuple's type be (WhiteKey, int)?  Thanks!

An enum does not extend other types.
It specifies what the type of the value will be.
It is a little like a map in that way.

I would recommend that the tuple to be the value type of the enum.
You could alias TypeTuple and use it directly and name the fields.
All it is, is a struct.