What c.l.py's opinions about Soft Exception?
John Nagle
nagle at animats.com
Mon Mar 10 01:12:16 EDT 2008
Steven D'Aprano wrote:
> On Sat, 08 Mar 2008 22:24:36 -0800, Kay Schluehr wrote:
>
>> On 9 Mrz., 06:30, Steven D'Aprano <st... at REMOVE-THIS-
>> cybersource.com.au> wrote:
>> Is it really so exotic that it requires the demand for more use cases?
>
>
> Are the existing solutions really so incomplete that we need yet another
> solution?
>
> What problem are you trying to solve with SoftExceptions?
I actually implemented something like "soft exceptions" in a LISP
program long ago. I called them "gripes". They were a way that a function
could complain about something it wanted the caller to fix. The caller
could either fix it or decline to do so.
This was for a robotic planning application, where one module had detected
that some precondition that it needed wasn't satisfied. This was usually
something like some physical object being in the wrong place for a later
operation, and a previously planned move needed to be modified. Passing
the problem back to the caller sometimes allowed an easy fix, rather than
aborting the whole plan and building a new one.
This isn't a common problem.
In the rare cases that it is needed, it can be implemented with callbacks.
It doesn't require a language extension.
John Nagle
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