• Steven Schveighoffer (10/10) Sep 13 2020 Consider the enum:
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (18/28) Sep 13 2020 It is a bit weird that x.stringof doesn't simply return the name
• Steven Schveighoffer (9/42) Sep 14 2020 Thanks.

Steven Schveighoffer <schveiguy gmail.com> writes:

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.

-Steve

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

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"

--
   Simen

Steven Schveighoffer <schveiguy gmail.com> writes:

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