[Zope-dev] zope.app.form: Make "no value" always available?

[Thomas Lotze]

Roger Ineichen wrote:

> Since this is a miss behavior and I agree that this should get fixed. We
> probably should think about a solution which supports the old behavior by
> default.
> 
> Note, this whould probably also break other packages like
> z3c.csvvocabulary.

We've thought about this some more. Our current suggestion is to implement
both behaviours using a class attribute for switching, with the base class
implementing the new, better one and a subclass setting the attribute
differently for BBB.

We'd like to register the base class with changed behaviour as the
default, though, in order to facilitate adoption of the new and better
implementation and provide an override registration for the BBB widget.
Applications would then have an easy migration path, having to add only
one line of ZCML after the zope.app.form update.

Also, we'd like to implement the new behaviour in such a way that the "no
value" value isn't shown for required fields that already have a valid
value set. What do others think about this?

Viele Grüße,
Thomas Lotze

-- 
Thomas Lotze · tl at gocept.com
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