On 2/18/22 06:19, kdevel wrote: > // auto b3 = B ("A", "B"); // Error: cannot implicitly convert > // expression `"A"` of type `string` to `A` Yeah, D disallows some implicit conversions. Adding a constructor to B will make it work: this(string as, string bs) { this.a = A(as); this.b = A(bs); } } Ali