Les Tyrrell wrote:
> 
> You might find the Messenger framework written by Paul Baumann
> to be worth looking at.  I haven't yet had a chance to use it,
> but plan to try it out in a few projects of mine coming up.
> 
> Messenger was one of the frameworks that Paul brought to the
> first Camp Smalltalk, so there is a desire ( if not the already
> existing capability ) to have it in the Squeak Smalltalk environment
> as well.  Information about Messenger, along with a link to the
> downloadable files, can be found at:
> 
> http://wiki.cs.uiuc.edu/CampSmalltalk/Messenger+project

The problem with this is that it's still aimed at talking with people.
My interest is more in non-interactive applications -- web servers,
machine controllers, etc. -- that may never have a person with whom
to communicate.

There are two problems that I see with this:

1. Text-based error descriptions don't allow easy special-case handling.
It is common to have to do one thing on a timeout (possibly different
in different contexts), and another on a transient failure of another
type, and yet another for a permanent failure.

The Exception hierarchy allows for this (and text messages can ride
along for free!)

2. There is a single recipient for the messages. Exception handling
allows scoped, nested exception handling. If one context can't handle
an exception, it can re-raise it. Or do something and raise another
exception. And it can be handled in a context that can actually do
something.

-- 
Ned Konz
currently: Stanwood, WA
email:     ned at bike-nomad.com
homepage:  http://bike-nomad.com