Before anyone spends time investigating, this has been accepted as an issue:
https://www.assembla.com/spaces/clojure/support/tickets/353 My workaround for now is to use reify in place of deftype. -Steve On 20 May 2010, at 13:43, Steve Purcell wrote: > I'm loving protocols, but I keep having to restart my JVM to avoid a puzzling > issue when changing protocol definitions. > > Here's the simplest way to reproduce the problem: > > Start with file protoproblem/proto.clj: > > (ns protoproblem.proto) > > (defprotocol Steps > (one [x]) > (two [x])) > > and file protoproblem/impl.clj: > > (ns protoproblem.impl > (:require [protoproblem.proto :as proto])) > > (deftype ArraySteps [a] > proto/Steps > (one [x] (first a)) > (two [x] (second a))) > > In the repl, everything works as expected: > > user> (load "protoproblem/proto") > nil > user> (load "protoproblem/impl") > nil > user> (protoproblem.proto/one (protoproblem.impl.ArraySteps. [1 2])) > 1 > > Now, we redefine the protocol by commenting out the 'one' method def in > proto.clj, and then reloading it: > > user=> (load "protoproblem/proto") > nil > user=> (protoproblem.proto/one (protoproblem.impl.ArraySteps. [1 2])) > java.lang.NullPointerException (NO_SOURCE_FILE:9) > user=> (load "protoproblem/impl") > java.lang.IllegalArgumentException: Can't define method not in interfaces: > one (impl.clj:5) > > That's pretty much as expected. But what if we try to get back to how things > were, by reversing the changes in proto.clj, and reloading? This is where the > problems arise: > > user=> (load "protoproblem/proto") > nil > user=> (load "protoproblem/impl") > nil > user=> (protoproblem.proto/one (protoproblem.impl.ArraySteps. [1 2])) > java.lang.IllegalArgumentException: No implementation of method: :one of > protocol: #'protoproblem.proto/Steps found for class: > protoproblem.impl.ArraySteps (NO_SOURCE_FILE:0) > > Ouch! > > At this point, I have to restart my JVM to proceed, which is making > incremental development of protocols-based code unusually tedious. > > I initially encountered the behaviour using "C-c C-k" under > slime/swank-clojure, but the above transcript is from a plain command-line > repl, using a Clojure 1.2 snapshot from today. (The same thing happened with > a snapshot from 2 weeks ago.) > > Is this a classloader issue, or something else? Any help greatly appreciated. > > -Steve > > -- > 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 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
