app.py

import zope.component as c

from zca import render, User, Lion, Kitty, Tiger, AnimalToID
from zca import TigerToID


c.provideAdapter(TigerToID)
c.provideAdapter(AnimalToID)


render(User('User', 'http://example.com/user.jpg', 20))
render(Lion('Lion', 'http://example.com/lion.jpg'))
render(Kitty('Kitty'))
render(Tiger('T', 'http://example.com/t1.jpg', 'http://example.com/t2.jpg'))

zca.py

import zope.interface as i
import zope.component as c


class IIdentificationCard(i.Interface):
    url = i.Attribute("""Subject picture URL.""")
    name = i.Attribute("""The name of the subject.""")


def render(obj):
    obj = IIdentificationCard(obj)
    print '<img src="%s" alt="%s">' % (obj.url, obj.name)


@i.implementer(IIdentificationCard)
class User(object):
    def __init__(self, name, url, age):
        self.name = name
        self.url = url
        self.age = age


class IAnimal(i.Interface):
    growling = i.Attribute("""The guttural vocalization of the animal.""")
    name = i.Attribute("""The name of the animal.""")
    picture = i.Attribute("""The URL of a picture of the animal.""")

#     def f(a, b):
#         """Docstring"""


@i.implementer(IAnimal)
class Lion(object):
    growling = 'Rarr!'

    def __init__(self, name, picture):
        self.name = name
        self.picture = picture


@i.implementer(IAnimal)
class Kitty(object):
    growling = 'Meew...'

    def __init__(self, name):
        self.name = name
        self.picture = '/kitty.jpeg'


@i.implementer(IAnimal)
class Tiger(object):
    growling = '?!?'

    def __init__(self, name, pic1, pic2):
        self.name = name
        self.picture = pic1
        self.picture2 = pic2


@c.adapter(IAnimal)
@i.implementer(IIdentificationCard)
class AnimalToID(object):
    def __init__(self, context):
        self.url = context.picture
        self.name = context.name


@c.adapter(Tiger)
@i.implementer(IIdentificationCard)
class TigerToID(object):
    def __init__(self, context):
        self.url = context.picture2
        self.name = context.name