On Nov 3, 2008, at 8:35 PM, Mark H. wrote:
> > On Nov 3, 5:39 pm, "Paul Stadig" <[EMAIL PROTECTED]> wrote: >> Could/Should the max function be modified to work against the >> Comparable interface instead of expecting its arguments to be >> numbers? >> >> I'm working with a sequence of strings that are dates in the >> "yyyy-mm-dd" format, and I want to find the max. Calling max gives an >> exception about not being able to cast to a java.lang.Number. > > I vote "no, max shouldn't be modified" because > > 1. The notation is ambiguous in the context of dates. What's the > "max" date? The most recent one, or the oldest one? > 2. Even if everyone agrees on what the "max date" of a sequence of > dates means, you're asking what "max" means for a sequence of > strings. You're thinking of some kind of dictionary order, but some > people might want to use string length. Since your version of max > would accept arbitrary strings, it would break for dates represented > using a different string format. > > The semantics of "max string" are unclear enough that it would be > better to write out the operation explicitly so that all readers of > the code know what you mean. > I think clearly spelling out how objects of a type should be sorted is the point of the Comparable interface. Therefore if the authors of a given class have determined an absolute ordering for instances of that class I'd expect max or anything that sorts a list to follow that definition. Users are free to create subclasses that overwrite that definition, to use a different function, or ideally to to pass some kind of function as a parameter to max (and functions like it) and use that parameter for the purpose of the comparison. - Cosmin --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
