interface 2c abstract python 3f

1from abc import ABC, abstractmethod
2
3class AccountingSystem(ABC):
4
5    @abstractmethod
6    def create_purchase_invoice(self, purchase):
7        pass
8
9    @abstractmethod
10    def create_sale_invoice(self, sale):
11        log.debug('Creating sale invoice', sale)
12

1class GizmoAccountingSystem(AccountingSystem):
2
3    def create_purchase_invoice(self, purchase):
4        submit_to_gizmo_purchase_service(purchase)
5
6    def create_sale_invoice(self, sale):
7        super().create_sale_invoice(sale)
8        submit_to_gizmo_sale_service(sale)
9

1from abc import ABCMeta, abstractmethod
2
3class IInterface:
4    __metaclass__ = ABCMeta
5
6    @classmethod
7    def version(self): return "1.0"
8    @abstractmethod
9    def show(self): raise NotImplementedError
10
11class MyServer(IInterface):
12    def show(self):
13        print 'Hello, World 2!'
14
15class MyBadServer(object):
16    def show(self):
17        print 'Damn you, world!'
18
19
20class MyClient(object):
21
22    def __init__(self, server):
23        if not isinstance(server, IInterface): raise Exception('Bad interface')
24        if not IInterface.version() == '1.0': raise Exception('Bad revision')
25
26        self._server = server
27
28
29    def client_show(self):
30        self._server.show()
31
32
33# This call will fail with an exception
34try:
35    x = MyClient(MyBadServer)
36except Exception as exc:
37    print 'Failed as it should!'
38
39# This will pass with glory
40MyClient(MyServer()).client_show()
41