Keeping DA's around

Article View: net.micro.mac

Article #1873

#1873

From: Larry Rosenstein
Date: Wed, 26 Jun 1985 01:50

22 lines
1502 bytes

There was a question a couple weeks ago about keeping DA's around after
launching a program.  I lost the original question, but I have an answer.

Desk accessories are implemented as drivers; most of the time they live on
the application's heap.  Launching an application (going back to the Finder
is the same as launching any application) completely wipes out the
application heap and the DA with it.  The launch code clears the device
control entry (DCE) for the driver to reflect the fact that the DA is no
longer around.

You can try placing the driver in the system heap, which is preserved
across program launches.  The launch code will zero out the DCtlWindow
fields of the DCE and also the DCtlStorage field if it is in the
application heap.  (You can't preserve the window because calling
InitWindows clears the window list.)

-- 
Larry Rosenstein
Apple Computer

UUCP:  {nsc, dual, voder, ios}!apple!lsr
CSNET: lsr@Apple.CSNET

Technical Details

Message-ID: <235@apple.UUCP>

Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!decwrl!sun!idi!apple!lsr

Show Full Headers

Complete Article Headers

Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1.chuqui 4/7/84; site apple.UUCP
Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!decwrl!sun!idi!apple!lsr
From: lsr@apple.UUCP (Larry Rosenstein)
Newsgroups: net.micro.mac
Subject: Keeping DA's around
Message-ID: <235@apple.UUCP>
Date: Tue, 25-Jun-85 21:50:56 EDT
Article-I.D.: apple.235
Posted: Tue Jun 25 21:50:56 1985
Date-Received: Thu, 27-Jun-85 08:01:18 EDT
Organization: Advanced Development Group, Apple Computer
Lines: 22