from abc import ABCMeta, abstractmethod
class IInterface:
__metaclass__ = ABCMeta
@classmethod
def version(self): return "1.0"
@abstractmethod
def show(self): raise NotImplementedError
class MyServer(IInterface):
def show(self):
print 'Hello, World 2!'
class MyBadServer(object):
def show(self):
print 'Damn you, world!'
class MyClient(object):
def __init__(self, server):
if not isinstance(server, IInterface): raise Exception('Bad interface')
if not IInterface.version() == '1.0': raise Exception('Bad revision')
self._server = server
def client_show(self):
self._server.show()
# This call will fail with an exception
try:
x = MyClient(MyBadServer)
except Exception as exc:
print 'Failed as it should!'
# This will pass with glory
MyClient(MyServer()).client_show()