enum to flags

[Cauterite via Digitalmars-d-learn]

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));