enum to flags

[Nicholas Wilson via Digitalmars-d-learn]

On Tuesday, 29 September 2015 at 06:08:03 UTC, Cauterite wrote:
> On Tuesday, 29 September 2015 at 03:31:44 UTC, Nicholas Wilson 
> wrote:
>> so I have a bunch of enums (0 .. n) that i also want to 
>> represent as flags ( 1 << n foreach n ). Is there anyway to do 
>> this other than a string mixin?
>
> You could cheat with operator overloading:
>
> 	enum blah {
> 		foo,
> 		bar,
> 		baz,
> 	};
> 	
> 	struct EnumToFlags(alias E) {
> 		template opDispatch(string Name) {
> 			enum opDispatch = 1 << __traits(getMember, E, Name);
> 		};
> 	};
> 	
> 	alias blahFlags = EnumToFlags!blah;
> 	
> 	static assert(blahFlags.foo == (1 << blah.foo));
> 	static assert(blahFlags.bar == (1 << blah.bar));
> 	static assert(blahFlags.baz == (1 << blah.baz));

Cheating is always good. I'l probably add some template 
constraints.

Thanks
Nic