Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!olivea!apple!lsr
From: lsr@Apple.com (Larry Rosenstein)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Software should be robust (was Common problem with Dialog Manager)
Message-ID: <11722@goofy.Apple.COM>
Date: 15 Jan 91 18:57:27 GMT
References: <47962@apple.Apple.COM> <1991Jan11.002919.12966@dartvax.dartmouth.edu> <1991Jan11.150446.16850@ux1.cso.uiuc.edu> <1991Jan11.173254.26319@dartvax.dartmouth.edu>
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In article <1991Jan11.173254.26319@dartvax.dartmouth.edu>, ari@eleazar.dartmouth.edu (Ari Halberstadt) writes:
> 
> Presumabely, Apple had the forethought to place a loop into the load
> segment routine, something like:

You get a System Error in this case.

> There is little reason why the program may not simply display an alert
> "Could not proceed since the disk is unreadable (error #-1234)"

True.  MacApp uses its own routine to pre-load a code segment and uses its
standard error handling code if the segment can't be loaded.  In theory,
this should abort back to the main event loop and display an alert.  (If
the failure is due to lack of memory, then it should work; if the heap is 
corrupted, then all bets are off.)

Since the ROM has no standard failure handling mechanism, it couldn't signal
a failure.  I think the Segment Loader has no other choice but to do
a System Error.

Larry