Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Locking the "chooser" user name?
Message-ID: <7697@hoptoad.uucp>
Date: 18 Jun 89 22:49:25 GMT
References: <1889@dogie.macc.wisc.edu> <22951@santra.UUCP>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 51

In article <22951@santra.UUCP> jmunkki@kampi.hut.fi.hut.fi (Juri Munkki) writes:
>How about setting the protected bit (with ResEdit) after setting the names?
>I don't know how the chooser would react to this, but it might work.

I tried it and got confusing results.  First, I was able to change the
name even with the 'STR ' resource's protected bit set.  However, it
appears that if you then go in and open the resource with ResEdit
again, it reverts to the previous name.  Open it once and it shows the
new name; close it and open it again, and it shows the old name.  This
is very strange behavior and I can only speculate on the reasons.  (I
don't feel like stepping through the DA in MacsBug to make sure,
frankly.)

It would appear that when the Chooser attempts to modify the 'STR '
resource, it receives an error.  This is what would be expected since
the protected bit is set.  However, it interprets this error as meaning
"resource not present" regardless of where the error happens or what is
the actual error code.  It then does an AddResource to create a new
copy of the 'STR ' with the new name, assuming that it has not yet
been set.

The Resource Manager is not sensitive to this error and will let you
create two resources with the same ID.  I believe this is what
happens.  However, at some point ResEdit is detecting this error and
deleting the later copy of the resource without telling you.  This is
why it pops up with the new value the first time, but reverts to the
old value the second time.  This would imply that the checking happens
when you close the window associated with a resource.  (Perhaps Jon
Singer could give some information on this?)

So the answer is -- this does not appear to be safe, as setting the
protected bit can cause the Chooser to introduce an error into the
resource file.  Furthermore, it does not work even if you consider the
error acceptable; since the Resource Manager will return the most
recently added copy of a duplicate resource, the newer (changed)
version of the name will persist.  You can verify this for yourself.
Set the protected bit and close the system file; bring up the Chooser
and change the name; close the Chooser; bring up Chooser again and see
that the name has in fact been changed; repeat the last two steps two
or three times just to make sure; give up and fix the resource file.

I don't mean to revert to cranky mode again, but this is the second
suggestion in the last couple of days that has been put forward without
spending a few minutes doing rudimentary testing with ResEdit.  This
kind of thing does not improve the network's signal to noise ratio.
-- 
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com
Postal: 424 Tehama, SF CA 94103; Phone: (415) 495-2934

"Please help support the moratorium on meaningless quotes in .signatures."
  -- Doug Asherman on rec.music.cd