Methods in enums

[WebFreak001]

We have UFCS in D, which allows us to define global methods that 
just take for example an enum as first argument, and then call 
that global method using syntax `enumArg.globalMethod(rest)` 
instead of `globalMethod(enumArg, rest)`. I think this is very 
useful for lots of scenarios.

However enums themselves can't contain any methods. I think for 
consistency with the other types, such as union, struct, 
interface, class, etc. it would be nice if enums could just 
contain member methods, similarly to how structs and unions work. 
You can't put any methods inside C structs, but D allows it, so 
why not also for enums?

This would allow selective imports for enums, e.g. `import 
somemod : MyEnum;` to also pull in all the global UFCS functions. 
Nowadays IDEs partially make this obsolete, especially if you 
already know the names of the "member methods" you can call on 
the enum, since they would auto-import this for you. But I think 
D's design allowing a lot of code writing without IDE would fit 
this feature very well, while also benefiting IDE users for 
automatically having all built-in custom enum functions available 
to aid discovery, especially of new libraries. Additionally 
static string parsing methods would naturally fit in there and 
also allow defining special methods such as toString or other 
special things that code such as std.conv uses.

Is there possibly a major reason why enums couldn't contain 
methods? What are your thoughts?

They would of course need a bit of new syntax, like possibly 
separating the enum values and methods with `;`, like what Java 
does, or having a more D-like syntax that just allows methods 
anywhere in the enum. I think the concept itself would fit into 
the language design very nicely.