Make enum auto castable

[Jonathan M Davis via Digitalmars-d-learn]

On Monday, June 05, 2017 00:16:15 Mike B Johnson via Digitalmars-d-learn 
wrote:
> On Sunday, 4 June 2017 at 23:39:11 UTC, Jonathan M Davis wrote:
> > On Sunday, June 04, 2017 22:52:55 Mike B Johnson via
> >
> > Digitalmars-d-learn wrote:
> >> [...]
> >
> > Aside from whatever implicit conversions are built into the
> > language, the only way to define an implicit conversion in D is
> > via alias this on a user-defined type, which then tells that
> > type that it can convert to whatever type the result of the
> > alias this is. e.g. if you have
> >
> > [...]
>
> I might be able to change the enum, I assume you mean something
> like
>
> enum myenum : S { }
>
> where S is the struct that implicitly converts?

Yes.

However, be aware that you can currently only define one alias this per
type. So, the rest of the code will then need to be able to deal with the
fact that the enum is a struct that implicitly converts to VARIANT and does
not implicitly convert to int. So, if you're just passing the enums around
and comparing them, you're fine, but if you need to treat them as ints
somewhere, then you'll need to provide an explicit conversion (via
overloading opCast or by creating a specific function for it or just
exposing a member with the int value or whatever), and that could get
annoying in the same way that you're annoyed about the VARIANT issue right
now.

But if you don't actually need to treat the enum as an int, and you can make
it a struct that implicitly converts to VARIANT instead, then that will fix
your VARIANT conversion problem.

- Jonathan M Davis