Newsgroups: comp.unix.wizards
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: OSF, and why it is a side issue
Message-ID: <1988May31.210815.5586@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1988May29.014006.4964@utzoo.uucp>, <11715@mimsy.UUCP>
Date: Tue, 31 May 88 21:08:15 GMT

> ... The battle cry of `compatibility' (which Henry
> himself has raised against some of the things Berkeley has done) serves
> to hinder the replacement or removal of misfeatures.

Agreed, but it does not make it impossible, necessarily.  It's an additional
and often annoying constraint on the process, but cleverness can still get
the job done much of the time.  The obvious method is the one that was used
in the V6-V7 transition, which Chris alluded to, to support the V6 stty()
and gtty() system calls even though V7 used ioctl() instead:  define the
new interface carefully and then implement the old one in terms of it.
Eventually you can consider removing the old interface, but the important
thing is that people can start doing it right without having all their
old software suddenly break.  It's not always possible to do this -- the
V6-V7 ioctl business was admittedly a favorable case -- but much can be
done if one tries.  (My complaint about Berkeley is that they seldom try.)

One does also need the courage (and backing) to break things now and then.
My belief is that it would be possible to produce a much cleaner system
that one could port to without experiencing *more* trouble than one does
going between variants today.  Note that I'm not saying it would be totally
painless, just that it would not require exceptional effort.
-- 
"For perfect safety... sit on a fence|  Henry Spencer @ U of Toronto Zoology
and watch the birds." --Wilbur Wright| {ihnp4,decvax,uunet!mnetor}!utzoo!henry