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: What to Remember, and When?
Message-ID: <7942@hoptoad.uucp>
Date: 11 Jul 89 04:38:55 GMT
References: <2184@husc6.harvard.edu> <26190@agate.BERKELEY.EDU>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 36

There's one sticky bit to all this state information mess that has yet
to be mentioned.  If you store this information for plain text files,
you will have to fake the modification date.  Consider this -- you open
a C source file, scroll around in it, and close it.  This causes the
position resource to be updated in the file's resource fork, and the
modification date becomes the present.  Now when that file is checked
against its object code, it looks as if it's out of date and needs to
be recompiled.

There's a similar problem on other kinds of files, but the misleading
modifcation dates are only visible to a human.  Still, just opening a
file and moving around in it should *not* change the apparent
modification date.

This is easily solved on the Mac OS by setting the mod date field in a
FileParam and calling PBSetFInfo.  MPW does exactly this with its state
resources.  But this operation may not be implemented on files on a
network file system on a non-Mac OS.  For instance, only the super-user
can change file dates on UNIX.  The server may be set up to let you do
this, or not.

It would be better in some ways if there were an OS call that stashed
this positional information with files on request without touching the
mod date, but if you think about it, that also creates some problems
on remote non-Mac file systems.

I don't have a solution -- I think the positional resource makes a lot
of sense for other reasons, a lot more sense than an application-specific
state saver.  I just thought these issues should be aired.
-- 
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com
Postal: 424 Tehama, SF CA 94103; Phone: (415) 495-2934

"Yet another piece of evidence that it's a Communist society which is being
 presented as good, but which we probably would not want to live in."
	-- Ken Arromdee on rec.arts.startrek, on the Federation's Red Menace