From: David Shochat <shochat@itg-sepg.logicon.com>
Subject: Re: Implementing pointers to pointers in Ada
Date: 1996/09/10
Date: 1996-09-10T00:00:00+00:00 [thread overview]
Message-ID: <3235E2C3.636F@itg-sepg.logicon.com> (raw)
In-Reply-To: 511sp9$ogs@newsbf02.news.aol.com
John Herro wrote:
> Of course, it's not obvious WHY you want to use two levels of indirection.
It was necessary for 68K Mac programming (I don't know about PPC). The
OS had to be able to move heap objects around whenever memory got tight,
so the programmer would access most GUI objects through a so-called
"handle" which was a pointer to a "master" pointer to the actual data.
In Meridian's Ada for the Mac, this was declared just as the examples in
this thread show (without the "all" -- it was Ada 83). This scheme was
crucial to allow the original Mac to run with only 128K. This scheme is
actually much older than the Mac.
-- David
next prev parent reply other threads:[~1996-09-10 0:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
1996-09-09 0:00 Implementing pointers to pointers in Ada Vasilios Tourloupis
1996-09-09 0:00 ` Norman H. Cohen
1996-09-09 0:00 ` Samuel Tardieu
1996-09-09 0:00 ` Mark A Biggar
1996-09-09 0:00 ` Jonas Nygren
1996-09-09 0:00 ` John Herro
1996-09-10 0:00 ` David Shochat [this message]
1996-09-11 0:00 ` Larry Kilgallen
1996-09-12 0:00 ` Dr. John B. Matthews
1996-09-13 0:00 ` Better MacOS Handles through Ada (was: Implementing Pointers to Pointe Larry Kilgallen
1996-09-14 0:00 ` Dr. John B. Matthews
1996-09-15 0:00 ` GUI Generators and Class Libraries (was: Better MacOS Handles Larry Kilgallen
1996-09-15 0:00 ` jim hopper
1996-09-16 0:00 ` Larry Kilgallen
1996-09-17 0:00 ` GUI Generators and Class Libraries Dr. John B. Matthews
1996-09-17 0:00 ` GUI Generators and Class Libraries (wa David Kristola
1996-09-10 0:00 ` Implementing pointers to pointers in Ada John Demby
1996-09-10 0:00 ` Robert A Duff
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