On Sat, Jun 27, 2009 at 4:30 PM, Handkea fumosa<hfum...@gmail.com> wrote: > > On Jun 27, 11:32 am, Meikel Brandmeyer <m...@kotka.de> wrote: >> Am 26.06.2009 um 23:44 schrieb Michael Spiegel: >> > =>(def foo (sorted-set "bob" "alice" "michael")) >> > => (contains? foo 5) >> > java.lang.ClassCastException: java.lang.String cannot be cast to >> > java.lang.Number (NO_SOURCE_FILE:0) >> >> IIRC, this came up already. And the general result was, >> that it is a bug in the user code to compare an Integer >> with a String. >> >> A sorted-set is not a usual set. It contains elements, >> which can be sorted according to an ordering. >> Comparing two things, where one is not in the domain >> of the ordering, is not defined. > > I'd agree that a ClassCastException is not inappropriate if you try to > put heterogeneous objects into a sorted-set. > > But contains? should probably just return true or false, never throw. > Michael's set doesn't contain 5; asking whether it does does not seem > to me to be an error. I think it would be desirable for contains? to > have returned false. A simple, crude way to make it do so would be to > wrap the original contains? code in a try ... catch that catches > ClassCastException and returns false if one gets thrown. >
Deducing it doesn't contain 5 because it was passed a key incomparable to some other key seems like a stretch to me, and bug-hiding. Clojure is relatively free of exception catching in normal flow of control, and I'm disinclined to start here. Rich --~--~---------~--~----~------------~-------~--~----~ 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 Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
