enums and std.traits

[Jonathan M Davis]

On Saturday, August 04, 2012 15:22:34 Jonathan M Davis wrote:
> On Sunday, August 05, 2012 00:15:02 Timon Gehr wrote:
> > T fun(T)(T arg) if(isSomeString!arg){
> > 
> >      return arg~arg[0];
> > 
> > }

> Though honestly, I'd argue that the compiler should treat arg ~ arg[0] as
> being string rather than the enum type anyway, since it makes no sense to
> get a new enum value by concatenating to an existing one. The new one
> probably isn't a valid enum value. It's the same problem that we get when
> we allow bit manipulation on enum types (which should also be disallowed
> IMHO). So, I think that that's more of a problem with enums than
> isSomeString.

Okay. I responded to that too quickly and mixed myself up a bit. The compiler 
already behaves this way. It unfortunately does type

return arg ~ arg;

as the enum type, but it correctly marks

return arg ~ arg[0];

as being a string, which does result in breakage. But the alternative right 
now is that using isSomeString breaks _all_ cases where an enum is passed 
rather than just some.

So, no, having isSomeString work with enums isn't perfect, but I still think 
that it's better than the current situation.

- Jonathan M Davis