Weird indeed: user=> (def a (atom 1)) #'user/a user=> (try (prn :test) (finally (swap! a inc) (.foo nil))) :test java.lang.NullPointerException (NO_SOURCE_FILE:0) user=> @a 3
I would have expected 2 as a result, in any case ? 2010/8/10 Meikel Brandmeyer <m...@kotka.de> > Hi, > > On Aug 10, 8:36 am, Brian Stiles <brian.sti...@gmail.com> wrote: > > > The following succeeds: > > > > (try > > (prn 1) > > (finally > > (prn 2) > > (doto (System/out) (.print "-") (.println "-")))) > > > > prints: > > > > 1 > > 2 > > -- > > > > The following fails (note the odd duplication of "2" in the output): > > > > (try > > (prn 1) > > (finally > > (prn 2) > > (.. (System/out) (print "-") (println "-")))) > > > > prints: > > > > 1 > > 2 > > -2 > > -Exception in thread "main" java.lang.NullPointerException > > Of course it fails, because print is a void method and hence "returns" > nil. So you are calling print on nil leading to the NPE. > > Why the 2 is printed twice... good question: > > user=> (try (prn 1) (finally (prn 2) (.foo nil))) > 1 > 2 > 2 > java.lang.NullPointerException (NO_SOURCE_FILE:0) > user=> (let [] (try (prn 1) (finally (prn 2) (.foo nil)))) > 1 > 2 > 2 > java.lang.NullPointerException (NO_SOURCE_FILE:0) > user=> (let [a (atom 2)] (try (prn 1) (finally (prn @a) (.foo nil)))) > 1 > 2 > java.lang.NullPointerException (NO_SOURCE_FILE:0) > user=> (def a (atom 2)) > #'user/a > user=> (try (prn 1) (finally (prn @a) (.foo nil))) > 1 > 2 > 2 > java.lang.NullPointerException (NO_SOURCE_FILE:0) > > Sincerely > Meikel > > -- > 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<clojure%2bunsubscr...@googlegroups.com> > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > -- 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
