Re: Get enum value name as string at compile time?

[Steven Schveighoffer via Digitalmars-d-learn]

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

Re: Get enum value name as string at compile time?

[Simen Kjærås via Digitalmars-d-learn]

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

Get enum value name as string at compile time?

[Steven Schveighoffer via Digitalmars-d-learn]

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