Path: utzoo!attcan!uunet!husc6!bloom-beacon!bu-cs!dartvax!eleazar.dartmouth.edu!earleh
From: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Change in System Tools 6.0 Menu Manager behavior.
Keywords: menuWidth -> -1, PopUpMenuSelect
Message-ID: <9549@dartvax.Dartmouth.EDU>
Date: 26 Jul 88 17:40:53 GMT
References: <9365@dartvax.Dartmouth.EDU> <14581@apple.Apple.COM>
Sender: news@dartvax.Dartmouth.EDU
Reply-To: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Organization: Dartmouth College, Hanover, NH
Lines: 40

In article <14581@apple.Apple.COM> tecot@apple.apple.com.UUCP 
	(Ed Tecot) writes:
>In article <9365@dartvax.Dartmouth.EDU> earleh@eleazar.dartmouth.edu 
	(Earle R. Horton) writes:
>>..., and why is this new behavior not documented anywhere?
>
>...  Since there were
>relatively few applications which use custom pop-ups, this problem was not
>discovered until too late.  It is not documented, and as such is considered
>antisocial behavior by this programmer.  It has been fixed in 6.0.1.

Thank you, Ed, for an honest explanation.

There are many, many structure members and parameters which are used
by "relatively few applications," but which appear in Inside Macintosh
to be "public" and therefore subject to consistent handling across
operating system releases.  The effects of such actions are in a sense
permanent, too.  Even though the problem may be fixed in 6.0.1, one
has no guarantees that his customers will not be using 6.0 at some
future time.  The programmer therefore must assume worst case, i.e.
that the operating system WILL change the value of menuWidth to -1 at
ALL times.  Otherwise he cannot assure consistent program behavior if
he is using pop-ups and needs to know their size.

I asked a question in my original posting which someone at Apple may
care to answer: How many other undocumented cases are there where the
system modifies shared variables or variables which actually "belong"
to the application, and not to the system?  Is Apple in the habit of
making such behavior public when they discover it, or only where they
get caught?  Do persons in authority at Apple frown on such behavior,
or is it an established technique there?

I am not banging on Apple here, but the degree of complication of the
Macintosh programmer interface seems to demand some extra degree of
assurance that things will not change unless they are well documented,
perhaps even beforehand.  If too many things like this happen, and
there is too little official explanation, then programming for the
Macintosh could become even more of a guessing game than it is now,
hardly a cheery prospect.
Earle R. Horton.  H.B. 8000, Dartmouth College, Hanover, NH 03755