constraint on variadic template

[Adam D. Ruppe via Digitalmars-d-learn]

On Wednesday, 7 December 2016 at 16:35:52 UTC, Alex wrote:
>     void run()
>     {
>         foreach(s; T)
>         {
>             static assert(__traits(hasMember, s, "run"));
>         }
>     }

Just put that in a function:

bool test(T...)() {
    foreach(s; T)
       if(!__traits(hasMember, s, "run"))
           return false;
    return true;
}

and use that as the constraint:

S(T...) if (test!T()) {}