Oh, nice! I've been wondering what this error means for at least a month now.
Thanks, James On Thursday, October 17, 2013 1:14:21 PM UTC-5, Alex Coventry wrote: > > If you've ever had a confusing > ArityException<http://clojure-log.n01se.net/date/2013-10-16.html#19:37> while > working with macros, the reason may be that > clojure.lang.Compiler.macroexpand1 rethrows any > ArityExceptions<https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Compiler.java#L6475>it > catches from a call to a macro, in order to reduce the number of > arguments reported. This messes up the stack, potentially destroying > information about where the ArityException occurred if it did not occur > from the call to the macro itself. For instance: > > user> (do (defn inner [] (assoc)) (defmacro f [] (inner)) (f)) > ArityException Wrong number of args (-2) passed to: core$assoc > clojure.lang.Compiler.macroexpand1 (Compiler.java:6488) > user> (use 'clojure.repl) (pst) > nil > ArityException Wrong number of args (-2) passed to: core$assoc > clojure.lang.Compiler.macroexpand1 (Compiler.java:6488) > clojure.lang.Compiler.macroexpand (Compiler.java:6544) > clojure.lang.Compiler.eval (Compiler.java:6618) > clojure.lang.Compiler.eval (Compiler.java:6624) > clojure.lang.Compiler.eval (Compiler.java:6597) > clojure.core/eval (core.clj:2864) > clojure.main/repl/read-eval-print--6596/fn--6599 (main.clj:260) > clojure.main/repl/read-eval-print--6596 (main.clj:260) > clojure.main/repl/fn--6605 (main.clj:278) > clojure.main/repl (main.clj:278) > clojure.tools.nrepl.middleware.interruptible-eval/evaluate/fn--1251 > (interruptible_eval.clj:56) > clojure.core/apply (core.clj:617) > nil > user> > > > Note that the call to inner is not in the stack trace, and the number of > arguments to it have been reduced by 2, leading to a nonsensical result in > this case. > > The patch at http://dev.clojure.org/jira/browse/CLJ-1279 fixes this bug. > Might save you some time, if you're developing macros. > > Best regards, > Alex > -- -- 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.
