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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Exceptions as objects (was Re: What is wrong with OO ?)
Date: 1997/01/25
Message-ID: <E4L0nu.DDs@world.std.com>#1/1
X-Deja-AN: 212197705
references: <5acjtn$5uj@news3.digex.net> <E49vLo.AzB@ecf.toronto.edu>
 <yf3lo9iqzhz.fsf@sabi.demon.co.uk> <32e9e445.163056932@library.airnews.net>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: 
 comp.lang.c++,comp.lang.smalltalk,comp.lang.eiffel,comp.lang.ada,comp.object,comp.software-eng
Date: 1997-01-25T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <32e9e445.163056932@library.airnews.net>,
Ronald E Jeffries <jeffries@ic.net> wrote:
>In a project I'm presently working on, the input routines try to
>handle all the errors.  Then when the application definers decided
>what kind of notifications they wanted on input errors, we had to go
>in and edit the input routines and change them all around to get the
>job done.  Had they just thrown an exception, we could have fielded
>the exception where we wanted to, and filed our notifications and gone
>on.

But this is true in Mr. Grandi's scheme, too.  Instead of raising an
exception, Mr. Grandi calls a function to handle the error.  And that
function is *dynamically scoped*, which means that the call site can
define it.  Just like the call site defines the handler code in the C++
or Ada way of doing things.

What you say above is the whole point of exceptions -- one piece of code
detects an error, and a different piece of code decides what to do about
it.  And Mr. Grandi's scheme is just as good as the C++/Ada scheme, in
this regard.  (I'm not sure why Mr. Grandi thinks his scheme is so
vastly superior, though.)

- Bob