> At 17:53 +0100 3/10/05, Thomas Sandlaß wrote: [request for clarification of 'covariant' and 'contravariant' usage] > >'Co' means together like in coproduction. And 'contra' is the opposite > >as in counterproductive. With instanciating parametric types the question > >arises how a subtype relation between instanciating types propagates > >to the template. E.g with Int <: Num, covariance would result in > >Array[Int] <: Array[Num]. Referential classes are actually quite difficult > >because upon write they are contravariant and covariant when read! > >So a third case of uncomparable types is needed as well, or it is the default > >if nothing else is specified.
Thomas, I appreciate you attempting to explain this, but it remains clear as mud, at least to me. Could you please try again, using very short, very non-technical words and not assuming a mathematical or scientific background on the part of your reader? Something that would help: We could all look the words up in a dictionary, so we don't need a definition. What we need is a clarification, in simple terms, of what *you* mean by them, in this context. Thank you. --Dks
