Newsgroups: comp.lang.objective-c
Path: utzoo!utgpu!cunews!greg
From: greg@cygnus.sce.carleton.ca (Greg Franks)
Subject: AsciiFiler/Unknown class.
Message-ID: <1990Nov22.215303.29686@ccs.carleton.ca>
Originator: greg@organia.sce.carleton.ca
Sender: news@ccs.carleton.ca (news)
Organization: Carleton University, Ottawa, Canada
Date: Thu, 22 Nov 90 21:53:03 GMT


Greetings.  We have an evolving application that adds new classes,
changes existing classes and disposes of old classes.  Adding new
classes is no problem.  We have a solution to the dreaded 'change
instance variable of a class and try to read in old versions problem'
that works for us so changing classes is no problem.  However, we have
now tried to dispose of a class.  No problem... Just link in 'Unknown'
and the old references will be read in and blown away.  Surprise
surprise.  The code for handling 'Unknown' in Filer.m has been
commented out.  Furthermore, the interface to Unknown has changed so
even if we compiled it back in it would still bomb.  Sooo, we have
left the old class linked in.  Question: Has anyone successfully used
Unknown??  If so, can they share the method for getting it work.
Enquiring minds want to know!

We are running objc 4.0.


Thanks
-- 
Greg Franks, (613) 788-5726               | "The reason that God was able to    
Systems Engineering, Carleton University, | create the world in seven days is   
Ottawa, Ontario, Canada  K1S 5B6.         | that he didn't have to worry about 
greg@sce.carleton.ca uunet!mitel!sce!greg | the installed base" -- Enzo Torresi