From: "Vladimir Olensky" <vladimir_olensky@yahoo.com>
Subject: Re: Ada GC (was Re: Ammo-zilla)
Date: 1999/11/04
Date: 1999-11-04T00:00:00+00:00 [thread overview]
Message-ID: <s23mnbp024223@corp.supernews.com> (raw)
In-Reply-To: 7vqd45$iiq$1@nnrp1.deja.com
Robert Dewar wrote in message <7vqd45$iiq$1@nnrp1.deja.com>...
>In article <s20tckqd24291@corp.supernews.com>,
> "Vladimir Olensky" <vladimir_olensky@yahoo.com> wrote:
>> As for me I fully support that.
>> I think that any unchecked conversions should
>> be disallowed for pointers that are traced by GC.
>> It is not only extremely unsafe but I do not see any sense
>> in that if language is extended to support GC.
>
>But that of course is not enough to prevent scary GC bugs :-)
Yes, I agree this does not prevent GC bugs that may exist
in GC implementation itself. But at least that could provide
isolation between GC implementation and GC client.
The last one will never be able to spoil anything in GC
internal data. Also, approach that I discribed yearlier
provides additional level of isolation between GC user
and GC internal data representation and it also allows
to achieve any desired level of sofisticated functionality .
Any pointer of "TRACED" ACCESS TYPE should never
reference real data. Instead it should only provide access to
the Address Descriptor Table entry for the allocated object .
Moreover, Address Descriptor Table structure is completely
hidden from the user. This is the same as protected
memory access in OS running in protected mode.
This already proved to be very effective in providing safety
and reliability.
>As soon as you allow the type safety of the system to be
>compromised in any way, it is possible that critical pointers
>will get damaged.
Again I agree here.
And again I would like to recall neat Modula-3 approach to the
safety issues that could also be very useful in Ada:
Any unsafe operations are allowed only in the modules marked
as UNSAFE . This marker says that here programmer and not
the system is responsible for safety. In modules without such
marker M3 does not allow any unsafe operation and safety
is guaranteed by the system itself. Such approach force
all (potentially) unsafe operations to be concentrated in few
unsafe modules instead of being scatted around.
Right now nothing forces Ada programmer (except his/her
internal discipline) to concentrate all unsafe operation in special
packages.
This reminds me discussions Ada vs. C& C++ where many times
many people were telling that Ada is better in this respect than C++
as C++ does allow to use unsafe and dangerous C style programming
and does not force to use new more safe C++ features.
Yes, Ada is much safer itself but it does not force as Modula-3
to put unsafe code in special places where such operations
could be easily traced and managed.
I think that some ideas implemented in M3 could be very useful in Ada .
There is nothing bad in using other's positive experience.
Here I could remind that Component Pascal (descendant of Oberon-2)
accepted some nice Ada features and they state that Ada positive
experiences were taken into account and that sounds good for me.
Regards,
Vladimir Olensky.
next prev parent reply other threads:[~1999-11-04 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 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 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
1999-10-28 0:00 ` Ammo-zilla Laurent Guerby
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 Tucker Taft
1999-10-30 0:00 ` Ammo-zilla Lutz Donnerhacke
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 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
1999-10-31 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 ` Vladimir Olensky
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
1999-11-01 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 ` Ammo-zilla Robert A Duff
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 ` Vladimir Olensky [this message]
1999-11-06 0:00 ` Ada GC (was Re: Ammo-zilla) Robert Dewar
1999-11-06 0:00 ` Vladimir Olensky
1999-11-06 0:00 ` Robert Dewar
1999-11-06 0:00 ` Vladimir Olensky
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
1999-10-31 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 ` Gnat IDE (was: Garbage colletion) Ted Dennison
1999-11-01 0:00 ` Garbage colletion 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 ` Larry Kilgallen
1999-11-01 0:00 ` Robert Dewar
1999-11-01 0:00 ` Lutz Donnerhacke
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
1999-10-28 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
1999-10-29 0:00 ` Ammo-zilla Robert I. Eachus
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
1999-10-31 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
1999-10-24 0:00 ` Ammo-zilla Robert Dewar
1999-10-24 0:00 ` Ammo-zilla David Botton
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