Typeinfo

[Adam D. Ruppe via Digitalmars-d]

On Friday, 3 April 2015 at 00:21:47 UTC, Andrei Alexandrescu 
wrote:
> Hey folks, is there any way to figure out whether a type is 
> immutable or shared given its typeinfo?

Yes: if it is an instance of TypeInfo_Invariant or 
TypeInfo_Shared.

void main() {
         string s;
         char[] c;
         assert(cast(TypeInfo_Invariant) typeid(s).next !is null);
         assert(cast(TypeInfo_Invariant) typeid(c).next is null);
}

The next is there because the array itself isn't immutable, so we 
look at the type inside.