For using references in general, here is a little example: [EMAIL PROTECTED]:~$ clj Clojure user=> (def foo (ref 0)) #'user/foo user=> foo #<Ref [EMAIL PROTECTED]> user=> @foo 0 user=> (ref-set foo 1) java.lang.IllegalStateException: No transaction running (NO_SOURCE_FILE:0) user=> (dosync (ref-set foo 1)) 1 user=> @foo 1 user=>
Notice that you have to wrap ref-set in a transaction using dosync, and reading the reference requires the @ macro. -Jeff Brian Doyle wrote: > I am parsing a file and to compare the current line > with the previous line of the file. I am using line-seq > to go thru the file and I thought I would create a > ref to store the previous line. When I want to update > the previous line value I can't seem to do it. I've > never used refs before so I'm sure I'm doing something > very stupid. > > (defstruct line :lat :lon :name) > > (defn convert [file] > (let [prev-line (ref (struct line))] > (with-open [r (reader file)] > (doseq [l (line-seq r)] > (let [ps (split #"," l) > c-line (struct line (ps 0) (ps 1) (ps 2))] > (if (not= c-line @pre-line) > (do ; do stuff here then update pre-line > (dosync ref-set pre-line (apply struct line (vals c-line))) > (println @pre-line)))))))) ; this prints out all nils > doesn't seem to work > > > > Sorry if this email is not formatted correctly. Something is wrong with > my browser > currently typing in a textarea. Thanks. > > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
