Hi, In message "Re: Question regarding <=> operator and Comparable Mixin" on Thu, 10 Nov 2005 02:27:12 +0900, Manuel Kasten <kasten.m / gmx.de> writes: |But if I return nil (just like Integer <=> String) <= is fine [line |009], but == behaves differently from what I expected. Why doesn't [line |11] return false like [line 10] does? I thought == is supposed to return |true or false, nothing else? "nil" denotes underlying assumption (<=> to return an integer value) is not met. Ruby sometimes use nil as a small error indicator. matz.