Thank you for your explanation. I also suspect there is some subtle
issue with the class file being used by the different constructors.
However, I would be surprised if this behaviour is intended, and that
the 'hackery' you proposed is the only, and prefered way of solving this.
To better illustrate the core issue, I updated the example slightly
as follows:
Premise:
defrecordissue.arecord and defrecordissue.protocol constitute some
library.
1. defrecordissue.arecord defines a record type, and a function that
will return an instance of the record:
(ns defrecordissue.arecord)
(defrecord ARecord [])
(defn make-record
[]
(->ARecord))
2. defrecordissue.protocol defines a protocol, and extends it to the
record type defined in 1. It also defines a public function
intended to be used by libraries:
(ns defrecordissue.aprotocol
(:require [defrecordissue.arecord])
(:import [defrecordissue.arecord ARecord]))
(defprotocol AProtocol
(afn [this]))
(extend-protocol AProtocol
ARecord
(afn [this] 42))
(defn some-public-fn
[]
(afn (defrecordissue.arecord/make-record)))
3. defrecordissue.consumer is a consumer of the library, knows
nothing of any protocols or records, but only wants to call a
function thats part of the public api:
(ns defrecordissue.consumer
(:require [defrecordissue.aprotocol]))
(defrecordissue.aprotocol/some-public-fn)
This fails with the same root cause.
I've created a new branch for this in the GitHub repo.
https://github.com/ragnard/defrecordissue/tree/more-realistic
/Ragge
On Thursday, 18 April 2013 12:19:35 UTC+1, Andrew Sernyak wrote:
>
> I guess extend-type does changes only to generated java class and the var
> defrecordissue.arecord->ARecord
> contains the 'old' version of ARecord constructor. Obviously it would be
> weird for defprotocol to change the variable in another namespace.
> Especially when you can extend a record from anywhere.
>
> So If you want to create a record that implements your protocol via var
> from record namespace, you should do some hackery to update that variable.
> I've done a pull-request for you, but using direct constructor will be more
> idiomatic
>
> ;
>> ; this won't work unless you update manualy a variable ->ARecord in the
>> namespace
>> ;
>> ;(defrecordissue.aprotocol/afn (defrecordissue.arecord/->ARecord))
>> ;
>> ; like
>> (defmacro from-ns[nmsps & body]
>> "launches body from namespace"
>> `(binding
>> [*ns* (find-ns ~nmsps)]
>> (eval
>> (quote (do ~@body)))))
>> (from-ns 'defrecordissue.arecord
>> (import '(defrecordissue.arecord.ARecord))
>> (alter-var-root
>> ('->ARecord (ns-publics 'defrecordissue.arecord))
>> (fn[x] (fn[] (new ARecord)))))
>> (println (defrecordissue.aprotocol/afn
>> (defrecordissue.arecord/->ARecord)))
>> ; 42
>
>
> ndrw
>
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