Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!mips!daver!tscs!tct!chip From: chip@tct.com (Chip Salzenberg) Newsgroups: comp.lang.c++ Subject: Re: typeof() and virtuals and overloading, oh my! Message-ID: <28007B1C.D1A@tct.com> Date: 8 Apr 91 14:15:55 GMT References: <157@devnull.mpd.tandem.com> <162@devnull.mpd.tandem.com> <6754@stpstn.UUCP> Organization: Teltronics/TCT, Sarasota, FL Lines: 31 According to lerman@stpstn.UUCP (Ken Lerman): >1 -- It is possible to save and restore arbitrarily complex graphs of >objects without explicit cooperation from each class. This is done in >Objective-C. I find this claim hard to believe. How does the freeze method know whether a |char *| member points to allocated memory? If it knows that it is allocated, how does it know whether that memory should be freed when the object is stored? Such questions seem unsolveable without cooperation from the class to be frozen. >3 -- It is NOT necessary that each class in Objective-C have the same >root class, but it IS necessary that each have a first instance >variable which is the "isa" pointer. The "isa" feature amounts to inheritance. "They have a data member in common, and they have these methods in common, but they're not derived from a common base class. Really!" Sure. >4 -- I don't understand the aversion to having a single root class for >those objects which we wish to make persistent. Nor do I. >Multiple inheritence might be good for this. I should hope so! -- Brand X Industries Custodial, Refurbishing and Containment Service: When You Never, Ever Want To See It Again [tm] Chip Salzenberg ,