But with a set, the ordering doesn't matter, since #{:foo :bar} = #{:bar
:foo}, so a set as a dispatch value should work just fine.On Mon, Jul 6, 2015 at 1:45 AM, <dmichu...@gmail.com> wrote: > The semantics of a set doesn't guarantee an order either (even though it's > implementation might), I'd sort over the keys and use the resulting > collection as hash-map key so you are independent of any clojure-intrinsic > behavior. > > > On Thursday, July 2, 2015 at 3:06:00 AM UTC+2, Fluid Dynamics wrote: >> >> On Wednesday, July 1, 2015 at 3:54:03 PM UTC-4, Jo Geraerts wrote: >>> >>> Hey, >>> >>> I when i tried to run my program with the shiny new 1.7, it broke. I >>> have traced it down to the fact that zipmap ( >>> https://github.com/clojure/clojure/blame/master/src/clj/clojure/core.clj#L2940) >>> does returns the keys in a different order than i'm used to. >>> >>> e.g clojure 1.6: >>> >>> nREPL server started on port 52315 on host 127.0.0.1 - nrepl:// >>> 127.0.0.1:52315 >>> REPL-y 0.3.5, nREPL 0.2.7 >>> Clojure 1.6.0 >>> Java HotSpot(TM) 64-Bit Server VM 1.8.0_40-b26 >>> Docs: (doc function-name-here) >>> (find-doc "part-of-name-here") >>> Source: (source function-name-here) >>> Javadoc: (javadoc java-object-or-class-here) >>> Exit: Control+D or (exit) or (quit) >>> Results: Stored in vars *1, *2, *3, an exception in *e >>> >>> user=> (zipmap [:a :b] [:c :d]) >>> {:b :d, :a :c} >>> >>> Whereas clojure 1.7 does: >>> >>> nREPL server started on port 52193 on host 127.0.0.1 - nrepl:// >>> 127.0.0.1:52193 >>> REPL-y 0.3.5, nREPL 0.2.7 >>> Clojure 1.7.0 >>> Java HotSpot(TM) 64-Bit Server VM 1.8.0_40-b26 >>> Docs: (doc function-name-here) >>> (find-doc "part-of-name-here") >>> Source: (source function-name-here) >>> Javadoc: (javadoc java-object-or-class-here) >>> Exit: Control+D or (exit) or (quit) >>> Results: Stored in vars *1, *2, *3, an exception in *e >>> >>> user=> (zipmap [:a :b] [:c :d]) >>> {:a :c, :b :d} >>> >>> As i'm using the keys function later on these values as a multimethod >>> dispatch function, things break. >>> >>> It's rather trivial to change my program with the new ordering, but i >>> was wondering if the ordering of the keys of the returned map is part of >>> the contract. >>> >>> When one would need more context about the actual code, the usage of the >>> zipmap can be found here at >>> https://github.com/jgeraerts/imageresizer/blob/master/src/net/umask/imageresizer/urlparser.clj#L19 >>> . >>> The multimethod dispatch >>> https://github.com/jgeraerts/imageresizer/blob/master/src/net/umask/imageresizer/resizer.clj#L15 >>> >>> The tests break with these kinds of exceptions: >>> >>> ERROR in (test-resizer) (MultiFn.java:156) >>> expected: (= [200 [200 200]] (run-resizer "size/200x200/rose-cmyk.tiff")) >>> 20:31:05.179 [main] WARN net.umask.imageresizer.resizer - image not >>> found for uri size/200x200/nonexisting >>> actual: java.lang.IllegalArgumentException: No method in multimethod >>> 'scale' for dispatch value: (:width :height) >>> at clojure.lang.MultiFn.getFn (MultiFn.java:156) >>> clojure.lang.MultiFn.invoke (MultiFn.java:233) >>> >>> I'm glad to hear your feedback. >>> >> >> Key order for (non-sorted) maps is not guaranteed, but there is an easy >> fix: pour the result of keys into a set, e.g. (into #{} (keys my-map)), and >> use #{:width :height} e.g. as your dispatch values. Then it will work >> independently of the vagaries of key ordering. >> > -- > 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/d/optout. > -- “One of the main causes of the fall of the Roman Empire was that–lacking zero–they had no way to indicate successful termination of their C programs.” (Robert Firth) -- 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/d/optout.
