From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Ada 'hello world' for Android; success!
Date: Wed, 2 Nov 2011 17:27:07 +0100
Date: 2011-11-02T17:27:07+01:00 [thread overview]
Message-ID: <ldib5ai6cc86.1fd7ya7biqreo$.dlg@40tude.net> (raw)
In-Reply-To: 82ipn2ms5p.fsf@stephe-leake.org
On Wed, 02 Nov 2011 11:59:46 -0400, Stephen Leake wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>
>> On Sun, 30 Oct 2011 07:32:59 -0400, Stephen Leake wrote:
>>
>>> In brief, _any_ framework that uses dispatching on class-wide
>>> objects needs reference semantics.
>>
>> Wrong. Reference semantics is required to maintain object's identity.
>
> Well, yes. What good is a system that does not maintain object identity?
Why should it? Most of the objects Ada creates lack run-time identity. Ada
also prevents the programmer from identifying such objects. E.g. by
X'Access for X without "aliased".
> Please rewrite my access_vs_object example, without using reference
> semantics. Note that I am explicitly including container cursors as a
> "reference type".
That is OK, cursor is a referential type, which identities the object it
points to. If the cursor is a publicly access type, that is fine to me.
Moreover I wished that all cursor types implemented "abstract access
interface".
> Or show me another real system that has dispatching on collections of
> heterogeneous objects without reference semantics.
Note that Ada does not have MD. So you just cannot dispatch on the
collection *and* the object in the collection. You probably meant a
different thing: to dispatch on an element of some collection. The word
"dispatch" is irrelevant to identity here, because identity comes from the
collection: the element must stay in the collection while the operation is
performed on it. Is it so?
Or did you mean that it would be impossible to implement a collection of
class-wide objects without pointers? This is true, but it does not imply
referential semantics. E.g. the objects still could be copied in and out
when accessed.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2011-11-02 16:26 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-27 1:18 Ada 'hello world' for Android; success! Stephen Leake
2011-10-27 7:12 ` Alex R. Mosteo
2011-10-28 12:51 ` Stephen Leake
2011-10-27 10:50 ` Jeffrey Creem
2011-10-28 13:01 ` Stephen Leake
2011-10-27 10:58 ` Brian Drummond
2011-10-28 1:37 ` Shark8
2011-10-28 12:22 ` Anatoly Chernyshev
2011-10-29 13:37 ` Stephen Leake
2011-10-29 14:46 ` Anatoly Chernyshev
2011-10-29 20:47 ` Brad Moore
2011-10-29 21:59 ` Anatoly Chernyshev
2011-10-30 3:51 ` Brad Moore
2011-10-30 7:20 ` Anatoly Chernyshev
2011-10-30 10:56 ` Stephen Leake
2011-10-30 17:32 ` Brad Moore
2011-10-29 15:32 ` Georg Bauhaus
2011-10-29 16:09 ` Simon Wright
2011-10-29 17:32 ` tmoran
2011-10-30 11:38 ` Stephen Leake
2011-10-29 20:51 ` Brad Moore
2011-10-30 11:32 ` Stephen Leake
2011-10-31 22:34 ` Randy Brukardt
2011-11-01 8:41 ` Stephen Leake
2011-11-01 9:30 ` Georg Bauhaus
2011-11-02 15:55 ` Stephen Leake
2011-11-02 17:37 ` Robert A Duff
2011-11-08 3:56 ` Randy Brukardt
2011-11-03 0:37 ` Georg Bauhaus
2011-11-03 11:36 ` Stephen Leake
2011-11-03 15:24 ` Robert A Duff
2011-11-03 18:43 ` Pascal Obry
2011-11-03 22:14 ` Georg Bauhaus
2011-11-04 8:48 ` Dmitry A. Kazakov
2011-11-04 12:18 ` Stephen Leake
2011-11-04 15:03 ` Georg Bauhaus
2011-11-05 16:56 ` Stephen Leake
2011-11-01 9:52 ` Dmitry A. Kazakov
2011-11-02 15:59 ` Stephen Leake
2011-11-02 16:27 ` Dmitry A. Kazakov [this message]
2011-11-02 17:38 ` Simon Wright
2011-11-10 17:25 ` Stephen Leake
2011-11-27 15:18 ` mockturtle
2011-11-28 22:35 ` Ada 'hello world' for Android; success! (but music player failure) Stephen Leake
2011-11-29 11:23 ` Georg Bauhaus
2011-11-30 3:33 ` Stephen Leake
2011-11-30 18:57 ` Georg Bauhaus
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