On Fri, Mar 1, 2013 at 3:44 PM, Joachim De Beule <joachim.de.be...@gmail.com
> wrote:
> Here is another (real) example:
>
> When I change the number of slots in a record, e.g. from
>
> (defrecord MyRecord [slot1 slot2] ...)
>
> to
>
> (defrecord Myrecord [slot1] ...)
>
>
>
Are you remembering to recreate the *instances* of the records after
redefinition? I suspect not and this is causing your problem.
I found this somewhat surprising when I first discovered it, but hopefully
this REPL session illustrates the point...
user> (defrecord MyRecord [slot1])
user.MyRecord
user> (def r1 (->MyRecord 1))
#'user/r1
user> (defrecord MyRecord [slot1 slot2])
user.MyRecord
user> (def r2 (->MyRecord 1 2))
#'user/r2
user> r1
#user.MyRecord{:slot1 1}
user> r2
#user.MyRecord{:slot1 1, :slot2 2}
user>
user> (type r1)
user.MyRecord
user> (type r2)
user.MyRecord
; r1 and r2 apparently have the same type, but
user> (= (type r1) (type r2))
false
; r2 is a different (jvm) class (because of different classloader
introduced by redefinition)
user> (def r3 (->MyRecord 3 4))
#'user/r3
; two instances from the same definition *do* have the same type
user> (= (type r2) (type r3))
true
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