Evaluator variables in conditional label assignment

@evalalways:=bc4 = Exists("/programfiles/Beyond Compare 4/BCompare.exe");
@evalalways:=bc5 = Exists("/programfiles/Beyond Compare 5/BCompare.exe");
@label:=return (bc5) ? "BC5" : (bc4) ? "BC4" : "No BC";

Details of @evalalways: