On Wed, Apr 22, 2009 at 1:28 PM, David Nolen <dnolen.li...@gmail.com> wrote:
> 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.
OK, I see the clever hack now. This could work, until murphy's law
kicks in and you get a false positive when two different sets of
private data produce the same hash... (or someone boinks the hash
value in the map).
Cheers,
Victor.
> 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
>> >
>> >
>> >
>> >
>> > >
>> >
>>
>>
>
>
> >
>
--~--~---------~--~----~------------~-------~--~----~
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
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
-~----------~----~----~----~------~----~------~--~---
