[Zope3-dev] Re: Alternate schema types

[Tres Seaver]

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Gary Poster wrote:

> On Jul 12, 2005, at 11:01 AM, Tres Seaver wrote:
> 
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>> I would like to break the hard-wired assumption in the forms / widgets
>> machinery that all schemas must be interfaces with fields;  in
>> particular, I would like to make the introspection of the fieldset  from
>> a given schema pluggable.
> 
> The use cases make sense to me.
> 
> An observation is that the proposed implementation only works with 
> zope.app.form and perpetuates some other assumptions within the 
> zope.app.form.utility module--assumptions that we have found  constraining.
> 
> The zope.formlib package (http://svn.zope.org/zope.formlib/trunk/, 
> formerly known as zc.page) already provides a more powerful  abstraction
> in IFormFields.  The abstraction is only helpful with the  zope.formlib
> utilities, though (not zope.app.form.utlilty).

Would a similar indirection work there?  E.g., instead of:

    >>> from zope import interface, schema
    >>> class IOrder(interface.Interface):
    ...     identifier = schema.Int(title=u"Identifier", readonly=True)
    ...     name = schema.TextLine(title=u"Name")
    ...     min_size = schema.Float(title=u"Minimum size")
    ...     max_size = schema.Float(title=u"Maximum size")
    ...     now = schema.Datetime(title=u"Now", readonly=True)

    >>> from zope.formlib import form
    >>> class MyForm:
    ...     form_fields = form.Fields(IOrder)

we could do:

    >>> from zope import interface, schema
    >>> class IOrder(interface.Interface):
    ...     identifier = schema.Int(title=u"Identifier", readonly=True)
    ...     name = schema.TextLine(title=u"Name")
    ...     min_size = schema.Float(title=u"Minimum size")
    ...     max_size = schema.Float(title=u"Maximum size")
    ...     now = schema.Datetime(title=u"Now", readonly=True)

    >>> from zope.formlib import IFormFields
    >>> class MyForm:
    ...     form_fields = IFormFields(IOrder)

and register zope.formlib.form.Fields as the "default" adapter factory
for IFormFields? (where IFormFields would be the 'IFormIntrospector'
I sketched)?

> A notable downside is that it is not an out-of-the-box fit for Zope 
> 2.8/Five, since the package relies on Python 2.4.  A Python 2.3  version
> probably would be easy enough, removing some of the Python  2.4 features.

Those are mostly decorator-based, right?  In that case, aren't they
basically sugar?


Tres.
- --
===================================================================
Tres Seaver          +1 202-558-7113          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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