Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!dlyons
From: dlyons@Apple.COM (David Lyons)
Newsgroups: comp.sys.apple
Subject: Re: deleting DA's from memory
Message-ID: <31991@apple.Apple.COM>
Date: 30 May 89 18:19:22 GMT
References: <31983@apple.Apple.COM> <10220@claris.com>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 29

In article <10220@claris.com> wombat@claris.com (Scott Lindsey) writes:
>From article <31983@apple.Apple.COM>, by dlyons@Apple.COM (David Lyons):
>
>> Under System Disk 5.0 and later, there are two new Desk Manager calls:
>> RemoveCDA and RemoveNDA (just like InstallCDA and InstallNDA, only different).
[...]
>Why couldn't you just send that DA a shutdown, at which point it *should* undo
>anything it has done.  Then just unload its segment.  Does the fear of mis-
>behaved DA's in this respect prevent it?

The purpose of the Shutdown routine for a CDA or NDA is *not* necessarily to
tell it to get its grubby fingers out of the system, unfortunately.  Consider
CDAs like MacroMate (a macro program which watches the keyboard for special
keystrokes during an interrupt routine & simulates extra keypresses when
appropriate).  It actually uses its ShutDown routine to *install* itself,
which is its only sensible alternative.

NDAs have an Init entry point called by DeskStartUp and DeskShutDown, but there
could be NDAs that leave stuff installed even after they are shut down (although
I don't know of any offhand).

 --Dave Lyons, Apple Computer, Inc.          |   DAL Systems
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