Tuple enumeration without integers or strings

[Paul Backus]

On Friday, 1 January 2021 at 23:14:43 UTC, Rekel wrote:
> I seem to have hit a bit of a wall when comparing D enums to 
> Java enums.
> Of course the latter is just a fancy class, though it'd be nice 
> to see partially equivalent usefulness regardless.
>
> For example, as soon as non-integer, non-string values are 
> given to enums things get messy for me when using switch cases, 
> I haven't yet found a satisfying way of doing this.

D's switch statement only works on strings and integers. For more 
complex values, the easiest thing is to just use an if-else chain.

If you really want to use a switch statement, you can do it by 
defining a function that maps each of your enum values to a 
unique integer; for example:

enum Wind { ... }

size_t index(Wind w)
{
     if (w = Wind.N) return 0;
     // etc.
}

void someFunction(Wind w)
{
     switch(w.index) {
         case Wind.N.index: // uses CTFE
             // ...
             break;
         // etc.
         default: assert(0);
     }
}