From: Robert A Duff <bobduff@world.std.com>
Subject: Re: Ammo-zilla
Date: 1999/11/01
Date: 1999-11-01T00:00:00+00:00 [thread overview]
Message-ID: <wcc66zmnw0h.fsf@world.std.com> (raw)
In-Reply-To: 7vhg2n$7ht$1@nnrp1.deja.com
Robert Dewar <robert_dewar@my-deja.com> writes:
> By the way, speaking as someone quite familiar with garbage
> collection (remember I chaired WG2.1 for many years, and
> was responsible for the SPITBOL compilers -- see for example
> the 1977 paper in SP&E that discusses a new GC algorithm used
> very successfully in SPITBOL), I find the mixture of low level
> system facilities, including those that let you break the type
> model, and GC to be very worrisome, sounds like it can easily
> create a debugging nightmare. Note that one of the reasons that
> GC can succeed in Java is the extremely limited nature of the
> language. GC is more practical in Ada if you severely restrict
> the subset of Ada you support, and eliminate for instance
> stuff like Unchecked_Conversion and address overlays.
>
> What for instance does it mean to do address overlays that
> reference the address of some object if the address of that
> object changes due to GC? I have no idea what a sensible answer
> to this question might be!
I think most languages (or implementations thereof) today that support
garbage collection also have interfacing-to-C capabilities, which
introduces all the issues you're worried about. If you pass pointers
into the C world, you end up pinning down objects "by hand" and so
forth, and yes, it is error prone and possibly inefficient.
I understand your concern, but I don't think it's all that bad -- I
don't think it's unreasonable to have Unchecked_Conversion of pointers
and garbage collection in the same language. You have to be careful,
and you have to minimize and isolate the low-level stuff. After all,
the mere existence of Unchecked_Conversion doesn't cause any problems --
you have to *use* it to cause trouble, and that's a programmer's choice.
- Bob
next prev parent reply other threads:[~1999-11-01 0:00 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-10-23 0:00 Ammo-zilla Stanley R. Allen
1999-10-24 0:00 ` Ammo-zilla Robert Dewar
1999-10-24 0:00 ` Ammo-zilla David Botton
1999-10-24 0:00 ` Ammo-zilla Aidan Skinner
1999-10-24 0:00 ` Ammo-zilla Robert Dewar
1999-10-24 0:00 ` Ammo-zilla David Botton
1999-10-28 0:00 ` Ammo-zilla Charles Hixson
1999-10-28 0:00 ` Ammo-zilla Matthew Heaney
1999-10-28 0:00 ` Ammo-zilla mitch
1999-10-29 0:00 ` Ammo-zilla Matthew Heaney
1999-10-28 0:00 ` Ammo-zilla Laurent Guerby
1999-10-28 0:00 ` Ammo-zilla Charles Hixson
1999-10-29 0:00 ` Ada and GC (Was Re: Ammo-zilla) Vladimir Olensky
1999-10-29 0:00 ` David Botton
1999-10-31 0:00 ` Vladimir Olensky
1999-10-30 0:00 ` Samuel T. Harris
1999-10-30 0:00 ` David Botton
1999-10-28 0:00 ` Ammo-zilla David Starner
1999-10-29 0:00 ` Ammo-zilla Larry Kilgallen
1999-10-29 0:00 ` Ammo-zilla David Starner
1999-10-29 0:00 ` Ammo-zilla David Botton
1999-10-29 0:00 ` Ammo-zilla mike
1999-10-29 0:00 ` Ammo-zilla David Botton
1999-10-31 0:00 ` Ammo-zilla Robert Dewar
1999-11-02 0:00 ` Ammo-zilla Charles Hixson
1999-11-03 0:00 ` Ammo-zilla Wes Groleau
1999-11-01 0:00 ` Ammo-zilla Geoff Bull
1999-10-29 0:00 ` Ammo-zilla Matthew Heaney
1999-10-29 0:00 ` Ammo-zilla Charles Hixson
1999-10-29 0:00 ` Ammo-zilla Tucker Taft
1999-10-30 0:00 ` Ammo-zilla Lutz Donnerhacke
1999-10-31 0:00 ` Ammo-zilla Robert Dewar
1999-10-31 0:00 ` Garbage colletion Lutz Donnerhacke
1999-11-01 0:00 ` Robert Dewar
1999-11-01 0:00 ` Lutz Donnerhacke
1999-11-01 0:00 ` Robert Dewar
1999-11-01 0:00 ` Lutz Donnerhacke
1999-11-01 0:00 ` Robert Dewar
1999-11-04 0:00 ` Didier Utheza
1999-11-04 0:00 ` David Starner
1999-11-01 0:00 ` Gnat IDE (was: Garbage colletion) Ted Dennison
1999-11-01 0:00 ` Garbage colletion Larry Kilgallen
1999-10-31 0:00 ` Ammo-zilla Robert Dewar
1999-10-31 0:00 ` Ammo-zilla David Starner
1999-11-01 0:00 ` Ada and GC. Was: Ammo-zilla Vladimir Olensky
1999-11-01 0:00 ` Tucker Taft
1999-11-02 0:00 ` Robert Dewar
1999-11-02 0:00 ` Charles Hixson
1999-11-03 0:00 ` Robert Dewar
1999-11-03 0:00 ` Charles Hixson
1999-11-02 0:00 ` Vladimir Olensky
1999-11-01 0:00 ` Vladimir Olensky
1999-11-01 0:00 ` Ammo-zilla Robert Dewar
1999-11-01 0:00 ` Ammo-zilla Robert Dewar
1999-11-01 0:00 ` Robert A Duff [this message]
1999-11-01 0:00 ` Ammo-zilla Vladimir Olensky
1999-11-01 0:00 ` Ammo-zilla Robert Dewar
1999-11-02 0:00 ` Ammo-zilla Robert A Duff
1999-11-02 0:00 ` Ammo-zilla Robert Dewar
1999-11-03 0:00 ` Ammo-zilla Vladimir Olensky
1999-11-03 0:00 ` Ammo-zilla Robert Dewar
1999-11-04 0:00 ` Ada GC (was Re: Ammo-zilla) Vladimir Olensky
1999-11-06 0:00 ` Robert Dewar
1999-11-06 0:00 ` Vladimir Olensky
1999-11-06 0:00 ` Vladimir Olensky
1999-11-06 0:00 ` Robert Dewar
1999-11-09 0:00 ` Robert A Duff
1999-11-10 0:00 ` Vladimir Olensky
1999-11-10 0:00 ` Richard D Riehle
1999-11-10 0:00 ` Robert A Duff
1999-11-10 0:00 ` Nick Roberts
1999-11-12 0:00 ` Robert I. Eachus
1999-11-12 0:00 ` Didier Utheza
1999-11-12 0:00 ` Robert Dewar
1999-11-12 0:00 ` Robert I. Eachus
1999-11-04 0:00 ` Ada GC (was Ammo-zilla) Nick Roberts
1999-11-04 0:00 ` Wes Groleau
1999-10-30 0:00 ` Ammo-zilla Lutz Donnerhacke
1999-10-30 0:00 ` Ammo-zilla Matthew Heaney
1999-10-31 0:00 ` Ammo-zilla Robert Dewar
1999-10-29 0:00 ` Ammo-zilla Robert I. Eachus
1999-10-28 0:00 ` Ammo-zilla Tucker Taft
1999-10-31 0:00 ` Ammo-zilla Brian Rogoff
1999-11-01 0:00 ` Ammo-zilla Robert Dewar
1999-11-01 0:00 ` Ammo-zilla Brian Rogoff
1999-11-02 0:00 ` Ammo-zilla Robert Dewar
1999-11-02 0:00 ` Ammo-zilla Brian Rogoff
1999-11-02 0:00 ` Ammo-zilla Robert A Duff
1999-10-31 0:00 ` Ammo-zilla Robert Dewar
1999-10-24 0:00 ` Ammo-zilla Aidan Skinner
1999-10-25 0:00 ` Ammo-zilla Jean-Pierre Rosen
1999-10-24 0:00 ` Ammo-zilla Matthew Heaney
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