python的接口实现zope.interface示例

python支持多继承，但是不支持接口，zope.inteface是其三方的接口实现库，在twisted中有大量使用

from zope.interface import Interface
from zope.interface import implementer
import socket

class IHostNameResolver(Interface):
    def getHostByName(name, timeout = (1, 3, 11, 45)): # 可以不用self
        """
        Resolve the domain name C{name} into an IP address.
        """

"""
类装饰器等价于：implementer(IHostNameResolver)(HostNameResolver)
"""
@implementer(IHostNameResolver)
class HostNameResolver:

    def getHostByName(self, name, timeout = (1, 3, 11, 45)):
        try:
            address = socket.gethostbyname(name)
        except socket.error:
            return 'none'
        else:
            return address

resolver = HostNameResolver()
print resolver.getHostByName('localhost')

# 判断HostNameResolver是否实现了接口IHostNameResolver
print IHostNameResolver.implementedBy(HostNameResolver) # True, 调用 SpecificationBasePy.implementedBy()