On 9/14/20 2:25 AM, Simen Kjærås wrote:
On Monday, 14 September 2020 at 03:48:51 UTC, Steven Schveighoffer wrote:
Consider the enum:
enum Foo { a, b }
Foo.a.stringof => "a"
enum x = Foo.a;
x.stringof => "cast(Foo)0"
Is there another way I can take an enum value that's known at compile
time (but not the actual identifier), and get the name of it? I know I
can use a switch, or to!string. But I was hoping this was easy for the
compiler to figure out some way without involving CTFE.
It is a bit weird that x.stringof doesn't simply return the name like
Foo.a.stringof does. Anyways, this works:
template enumName(alias a) {
import std.meta : staticIndexOf, staticMap;
alias T = typeof(a);
enum getValue(string name) = __traits(getMember, T, name);
alias enumValues = staticMap!(getValue, __traits(allMembers, T));
enum enumName = __traits(allMembers, T)[staticIndexOf!(a,
enumValues)];
}
enum Foo { a = 2, b = 19 }
enum x = Foo.a;
pragma(msg, enumName!x); // "a"
Thanks.
I never considered doing something like that. Not sure I like that
better than the CTFE version. I just punted and used to!string in my
code anyway.
A CTFE linear search in a compile-time array probably wouldn't be too
bad, especially when the list of elements is not long.
Again, we could use that ... DIP to make things a lot less complex.
-Steve
