[BlueBream] [Zope-dev] Referring to same interface using zope.schema.Object
jh at improva.dk
Fri Jul 22 08:53:29 EDT 2011
On 2011-07-22 14:32, Joshua Immanuel wrote:
> On Fri, 2011-07-22 at 13:41 +0200, Jacob Holm wrote:
>> On 2011-07-22 13:26, Brian Sutherland wrote:
>>> This would be my first guess:
>>> class INode(Interface):
>>> INode.parent = Object(
>>> title=u"Parent node",
>>> INode.children = List(
>>> title=u'Child nodes',
> The method suggested by Brian works without any issues. :)
It "works" only in the the sense that it doesn't throw an exception.
It does not define the desired schema.
>> And that guess would be wrong. You can't add fields to an existing
>> schema like that (not sure if you can in other ways). You *can*
>> an existing field however, so a working solution would be:
>> class INode(Interface):
>> parent = Object(
>> title = u'Parent node',
>> schema = Interface, # set to INode later
>> children = List(
>> title = u'Child nodes',
>> value_type = Object(schema=Interface),
>> INode['parent'].schema = INode
>> INode['children'].value_type.schema = INode
> I thought this also should work without any issues.
Trust me, it does.
> But when I ran the
> debug shell to list out the attributes of INode using dir(INode) I
> couldn't find the 'parent' and 'children' attributes in it.
The fields of the schema are not *supposed* to show up in "dir()".
Despite the use of the "class" statement to define them, interfaces are
*not* classes. They are instances of
zope.interface.interface.InterfaceClass, and act like (read-only)
containers of their fields.
Try using 'list(Inode)' for testing and you will see that "my" method
works as expected.
> Even worse
> part is, if there is another field say
> name = TextLine(title=u'Node name')
> This 'name' attribute is also is not visible along with 'parent' and
> 'children' attributes.
> Can someone explain why is this so?
Right. As explained above, it isn't supposed to.
> (Even though the problem gets solved by Brian's method, just curious to
I hope to have convinced you by now that it really isn't solved by
Brian's method, but by mine. (Although I wouldn't call it "my" method
as such. I'm sure I have taken it from somewhere else)
More information about the bluebream