[Zope3-dev] best way to deal with dependency errors

[Casey Duncan]

On Tue, 10 Feb 2004 04:38:26 -0500
Jim Fulton <jim at zope.com> wrote:

[..]
> The ConfirmationRequired exception has a view that:
> 
>    - Displays the issues and a confirmation button
> 
>    - Includes hidden fields that identify the issue.
>      This is needed to make sure that we have confirmed all
>      of the same issues when the application is reexecuted.

This is an interesting pattern. Interactive exception views. Actually I
think that in a well-mannered application, most exceptions should be
interactive in some way.

In general application exception views are a way for the app to express
an "Oh crap, I'm too stupid to figure this out for myself, what should I
do now?".

A simple example would be a transitory error, like lets say a conflict
that recurs after 3 retrys. It could perhaps have a "Try Again" button
that lets the user replay the request.

Or let's say a user tried to delete a locked item. If the user can
unlock the object then the exception view could have a "Delete Anyway"
button that unlocks the object and retrys the delete.

Or let's say you are adding a new item to a folder and you choose a name
that already exists. The exception view could provide a form where the
user can choose a different name.

All of these assume some way to store enough info about the previous
request to replay it (sometimes with modifications). There are of course
many ways to do this, but it would be nice to have this automated by the
framework in some way since it is a common operation.

We may want to think about not limiting this sort of functionality to
events. Otherwise I see myself using events just to get this nice
"resolve issues" functionality even if I wouldn't otherwise use them.
OTOH, maybe that should be a reason to use events.

-Casey