Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!rutgers!ames!sdcsvax!ucbvax!GRIN2.BITNET!MCGUIRE From: MCGUIRE@GRIN2.BITNET Newsgroups: comp.os.vms Subject: RE: Are Transfer Vectors Truly Useful When Creating Shareable Images? Message-ID: <8707281945.AA02228@ucbvax.Berkeley.EDU> Date: Mon, 27-Jul-87 14:16:00 EDT Article-I.D.: ucbvax.8707281945.AA02228 Posted: Mon Jul 27 14:16:00 1987 Date-Received: Thu, 30-Jul-87 01:34:14 EDT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 21 > Date: 25 Jul 87 16:34:27 GMT > From: Bengt Baeverman> Subject: Re: Are Transfer Vectors Truly Useful When Creating Shareable > Images? > > The easiest thing I can think of is using a vector, just like the transfer > vector, to access the data. All the UNIVERSAL symbols are really pointers to > the symbols you want to access. In fact, you can even maintain compatibility if the data types change, if you point to a descriptor instead of a data object. For example, if you decide to change a word to a longword in your shareable code, you can maintain backward compatibility by supporting word arguments as long as you like, even while writing new applications that pass longwords. Of course, this requires you to perform conditional branches and conversions based on the data type in the descriptor. Ed McGuire Systems Coordinator Grinnell College MCGUIRE@GRIN2.BITNET