enums and std.traits

[Jonathan M Davis]

On Sunday, August 05, 2012 00:15:02 Timon Gehr wrote:
> On 08/04/2012 11:09 PM, Jonathan M Davis wrote:
> > I agree that an enum's base type should not implicitly convert to the enum
> > type, since that would mean that you could have an invalid enum value, but
> > I see no problem with enums implicitly converted to their base type.
> Well, there is a problem:
> 
> T fun(T)(T arg) if(isSomeString!arg){
>      return arg~arg[0];
> }
> 
> The constraint would be too weak.

True, but that's still going to cause a lot fewer problems than making 
isSomeString fail for enums will, and if auto is used, then it's not a 
problem.

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.

- Jonathan M Davis