AsciiFiler/Unknown class.

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2 total messages Started by Greg Franks Thu, 22 Nov 1990 21:53

#160

Author: Greg Franks
Date: Thu, 22 Nov 1990 21:53

24 lines
1600 bytes

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

Re: AsciiFiler/Unknown class.

#169

Author: Gavin Finnie
Date: Tue, 04 Dec 1990 10:26

17 lines
1341 bytes

In article <1990Nov22.215303.29686@ccs.carleton.ca> greg@cygnus.sce.carleton.ca
(Greg Franks) writes:
>
>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.

I would be interested to see people's solutions to this general problem
(not just the specific question about the Unknown class), since it is a
potential headache when maintaining a large system written in Objective-C.

Gavin Finnie                             email:  gavin@praxis.co.uk
Praxis Systems plc                                       
20 Manvers Street                        phone: +44-225-444700
Bath BA1 1PX, England                    fax:   +44-225-465205

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