Thank you for your responses, Marek and Elias. Elias, you hit it square on the head - I was using Java 6, and changing to Java 7 corrected the issue. If you don't mind me asking, how did you even know about this behavior? This isn't the type of information you typically see on Hacker News, albeit much more helpful! :)
On Wednesday, October 2, 2013 7:17:40 PM UTC-7, Elias Zaretsky wrote: > > Are you using Java 6 by any chance? This issue may be due to a gotcha in > java.util.EnumMap. The implementation of the entry set iterator in EnumMap > in Java 6 is unorthodox [1]. Its next() method always returns the same > object, which is mutated to "point" to different entries in the map as the > iterator moves forward. This explains the behavior you are observing. Try > switching to Java 7 or make sure you call the keys function every time you > need the sequence of keys. > > [1] > http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/util/EnumMap.java#EnumMap.EntryIterator > > Thanks, > Elias. > > On Wednesday, October 2, 2013 5:19:31 PM UTC-4, James Warren wrote: >> >> I've been using Clojure for a couple months, so while I feel comfortable >> with it, I'm not certain whether some unusual behavior I encountered is a >> bug or a lack of understanding on my part. (I suspect the latter.) >> >> The context arose from using Clojure reflection to inspect a class >> generated by Apache Thrift <http://thrift.apache.org>. Such classes have >> a static, unmodifiable map describing the members of the class. I wrote a >> function to extract the keys of this map; it initially appears to work, but >> "def"ing the results to a symbol and repeatedly using that symbol returns >> inconsistent results. >> >> I've boiled it down to a smaller example that replicates the result: (gist >> available <https://gist.github.com/jameswarren/6799309>) >> >> // Java class >> >> public class DummyClass { >> public enum DummyEnum { >> FIRST, SECOND, THIRD >> } >> >> public static final Map<DummyEnum, String> dummyMap; >> static { >> Map<DummyEnum, String> tmpMap = new EnumMap<DummyEnum, >> String>(DummyEnum.class); >> tmpMap.put(DummyEnum.FIRST, "first"); >> tmpMap.put(DummyEnum.SECOND, "second"); >> tmpMap.put(DummyEnum.THIRD, "third"); >> dummyMap = Collections.unmodifiableMap(tmpMap); >> } >> } >> >> // Clojure ns >> >> (ns refbug.core >> (:import [refbug DummyClass])) >> >> (defn foo [^Class c] >> ;; note: (into [] (keys (clojure.lang.Reflector/getStaticField c >> "dummyMap")))) works >> (keys (clojure.lang.Reflector/getStaticField c "dummyMap"))) >> >> (def m (foo DummyClass)) >> (println m) >> ;; (#<DummyEnum FIRST> #<DummyEnum SECOND> #<DummyEnum THIRD>) >> (println m) >> ;; (#<DummyEnum THIRD> #<DummyEnum THIRD> #<DummyEnum THIRD>) >> >> Two different values upon successive calls using m. Is this expected? And >> if so, why? >> >> Many thanks, >> -James >> >> -- -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
