NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/sys/mac/programm/20089

Text File | 1992-12-21 | 1.6 KB | 36 lines

Newsgroups: comp.sys.mac.programmer
Path: sparky!uunet!spool.mu.edu!yale.edu!think.com!rpi!deweeset
From: [e-mail] (Thomas E. DeWeese)
Subject: Re: Duplicate Object in Think C?
Message-ID: <d![e-mail]>
Nntp-Posting-Host: ptolemy3.rdrc.rpi.edu
Organization: Rensselaer Polytechnic Institute, Troy, NY
References: <[e-mail]> <[e-mail]>
Date: Sat, 19 Dec 1992 20:26:00 GMT
Lines: 24

In article <[e-mail]> [e-mail] writes:
>In article <[e-mail]>, [e-mail] (Steve White) writes:
>> How do you duplicate an object without knowing its class?  We would like
>> to write something like
>>
>> r = duplicate( p );

  Well CObject has a Copy meathod.  So you can simply define a Copy meathod
for your subclass of the object, that copies it (it might be that the default
meathod can figure the size of all objects thus you would not need to
redefine it).
  If you don't use CObject as your base class, then simply add the meathod
to your base class, (and possibly copy the code from CObject).  And if you
are not using a single base class for all of your objects, you should add one
after all they all share the fact that they are in your application.
Then simply cast all of the object to your base class before passing them
in.
  If you have any more questions let me know.  BTW None of this would be a
problem if the world had decided to use a reasonable implementation of objects
like Objective C, where an object knows what type it is.
                            Thomas DeWeese
[e-mail]