You're missing the clever hack ;) I'm hashing the private data structure and
associating it to the map. This is what is used in the equality test. You
can verify yourself that it works.
my-object ;; -> {:private -1261861093}
my-other-object ;; -> {:private -1261861093}
Make sense? A few quick tests show that the hash of a data structure will
match on any VM.
On Wed, Apr 22, 2009 at 1:01 PM, Victor Rodriguez <vict...@gmail.com> wrote:
>
> On Tue, Apr 21, 2009 at 12:01 PM, David Nolen <dnolen.li...@gmail.com>
> wrote:
> > Nice post thanks for putting it together. My gut feeling is that the
> need
> > for information hiding is still overinflated, but... until someone builds
> a
> > 200k LOC Clojure program who will know for sure?
> > Here's my shot at a solution for private data:
> > (defn set-private [m k x]
> > (let [the-meta (meta m)
> > new-private (assoc (:private the-meta) k x)]
> > (with-meta
> > (assoc m :private (hash new-private))
> > (assoc the-meta :private new-private))))
> > (defn get-private [m k]
> > (get (:private (meta m)) k))
> > (def my-object (set-private {} :first "Bob"))
> > (def my-other-object (set-private {} :first "Bob"))
> > (get-private my-object :first) ; -> "Bob"
> > (= my-object my-other-object) ; -> true
> > No secret keys, no other libraries, and I believe this supports equality
> > just fine. Since we're using metadata the data travels around easily
>
> This won't work, since metadata is not used for equality tests, isn't
> that right?
>
> Regards,
>
> Victor Rodriguez.
>
> > between operations.
> > ---------- Forwarded message ----------
> > From: Mark Engelberg <mark.engelb...@gmail.com>
> > Date: Tue, Apr 21, 2009 at 6:41 AM
> > Subject: Re: Abstract data types in functional languages
> > To: clojure@googlegroups.com
> >
> >
> >
> > On Mon, Apr 20, 2009 at 11:00 AM, Timo Mihaljov <noid....@gmail.com>
> wrote:
> >> Is the concept of Abstract Data Types [1] useful in Clojure?
> >>
> >> If yes, how would you implement one?
> >
> > I have composed a lengthy response to this question, and added it to my
> > blog:
> > http://programming-puzzler.blogspot.com/2009/04/adts-in-clojure.html
> >
> > I look forward to everyone's comments,
> >
> > Mark
> >
> >
> >
> >
> > >
> >
>
> >
>
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