Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!tut.cis.ohio-state.edu!rutgers!sunybcs!boulder!pratt
From: pratt@boulder.Colorado.EDU (Jonathan Pratt)
Newsgroups: comp.sys.mac.programmer
Subject: Re: serious code generation bug in Lightspeed C
Summary: It has been documented!!!
Message-ID: <5838@boulder.Colorado.EDU>
Date: 15 Jan 89 18:47:41 GMT
References: <6275@hoptoad.uucp> <1676@helios.ee.lbl.gov> <6315@hoptoad.uucp>
Sender: news@boulder.Colorado.EDU
Reply-To: pratt@boulder.Colorado.EDU (Jonathan Pratt)
Organization: University of Colorado, Boulder
Lines: 36

In article <6315@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes:
>OK, I stand corrected.  The evaluation order is undefined.  Thanks to
>those who pointed this out, and particularly to those who pointed out
>what a weird and frustrating problem it is regardless.
...
>It is silly to say that this is a well documented problem.  I've read
>three drafts of Inside Mac, starting with the loose-leaf binder edition
>unfathomable aeons ago, and that an assignment could require locking
>has never been explicitly mentioned.  Dennis Cohen claims that it was
>mentioned in a comment in one of the earliest programming examples on
>the Mac.  This is not documentation, this is source code, and I hope
>Apple doesn't become as bad as Sun at understanding the difference.
>This is not a documented problem at all, much less well documented.

As I struggle to avoid turning on the flame thrower...

From the ancient (10/9/84) promotional edition of IM (the phone book)
memory management chapter, page 11:

The Pascal compiler frequently dereferences handles during its normal
operation.  You should take care to write code that will not require
the compiler to deference [sic] handles in the following cases:

- Use of the WITH statement with a handle, such as

    WITH aHandle^^ DO ...

- Assigning the result of a function that can move or purge blocks
  to a field in a record referred to by a handle, such as

    aHandle^^.field := NewHandle(..)

And so on.  The last example is the most relevant - *well documented*.

Jonathan
pratt@boulder.colorado.edu