[Zope3-dev] Re: Poll example for ObjectWidget

[Peter Mayne]

I've been trying to figure out why the Poll example in 
zope/app/form/browser/widgets.txt doesn't work.

The zope.app.form.CustomWidgetFactory class (which is used in the custom 
views) creates a widget as follows:

     def __call__(self, context, request):
         args = (context, request) + self.args
         instance = self._widget_factory(*args)
         for item in self.kw.items():
             setattr(instance, item[0], item[1])
         return instance

The SequenceWidget class has the following:

     def __init__(self, context, value_type, request, subwidget=None):
         super(SequenceWidget, self).__init__(context, request)

         self.subwidget = None

The initializer has the extra parameter value_type between context and 
request, so the arguments that the factory builds cannot match 
__init__(), hence the error:

   File "/opt/ZopeX3-3.0.0/lib/python/zope/app/form/__init__.py", line 
92, in __call__
     instance = self._widget_factory(*args)
TypeError: __init__() takes at least 4 arguments (3 given)

when attempting to add a Poll object.

Removing the value_type parameter from SequenceWidget.__init__() makes 
Poll work fine, and since value_type isn't used anyway...

Alternatively, changing the def to:

     def __init__(self, context, request, value_type=None, subwidget=None):

works too.

(Needless to say, this breaks the tests for SequenceWidget because they 
all pass the value_type argument, but removing the now extraneous 
TextLine() argument from each test widget creation fixes that.)

Presumably all widgets should conform to the

	def __init__(self, context, request, ...):

style to match the CustomWidgetFactory; there's no documentation for 
CustomWidgetFactory or IViewFactory that says it only works for a subset 
of widgets. However (for instance), ItemDisplayWidget inherits from 
ItemsWidgetBase, which has

	def __init__(self, field, vocabulary, request):

which would have to be

	def __init__(self, field, request, vocabulary):

to be able to be created by CustomWidgetFactory.

So, exactly how confused am I? :-) I've read 
zope/app/form/browser/README.txt, and I'm none the wiser as to what 
should be happening here.

PJDM
-- 
Peter Mayne
Spherion Technology Solutions
Canberra, ACT, Australia
"You're given the form, but you have to write the sonnet yourself.
What you say is completely up to you." - Mrs. Whatsit