I have started using Zope interfaces in my code, and as of now, they are really only documentation. I use them to specify what attributes the class should possess, explicitly implement them in the appropriate classes and explicitly check for them where I expect one. This is fine, but I would like them to do more if possible, such as actually verify that the class has implemented the interface, instead of just verifying that I have said that the class implements the interface. I have read the zope wiki a couple of times, but still cannot see much more use for interfaces than what I am currently doing. So, my question is what else can you use these interfaces for, and how do you use them for more.
You can actually test if your object or class implements your interface.
For that you can use verify module (you would normally use it in your tests):
>>> from zope.interface import Interface, Attribute, implements
>>> class IFoo(Interface):
... x = Attribute("The X attribute")
... y = Attribute("The Y attribute")
>>> class Foo(object):
... implements(IFoo)
... x = 1
... def __init__(self):
... self.y = 2
>>> from zope.interface.verify import verifyObject
>>> verifyObject(IFoo, Foo())
True
>>> from zope.interface.verify import verifyClass
>>> verifyClass(IFoo, Foo)
True
Interfaces can also be used for setting and testing invariants. You can find more information here: