Making enum join variadic

[Artur Skawina via Digitalmars-d-learn]

On 05/02/14 15:38, "Nordlöw" via Digitalmars-d-learn wrote:
> 
> template MemberNamesUnion(E...) if (allSatisfy!(isEnum, E))
> {
>     bool[string] allMembers;   // used to detect member collisions
>     mixin({
>             string r = "enum MemberNamesUnion { ";
>             foreach (T; E) {
>                 import std.range: join;
>                 foreach (member; __traits(allMembers, T)) {
>                     static assert (member in allMembers, "Member collision");
>                     allMembers[member] = true;
>                 }
>                 r ~= [__traits(allMembers, T)].join(",") ~ ",";
>             }
>             return r ~ " }";
>         }());
> }
> 
> It fails as
> 
> enums.d(25,46): Error: static variable allMembers cannot be read at compile time
> enums.d(25,21):        while evaluating: static assert("a" in allMembers)
> 
> Is there a solution to this problem?

Move the AA declaration to inside the lambda, remove the 'static'
from the assert, and fix the condition ("member !in allMembers"), then
it will work.

artur