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python抽象基类用法实例分析

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Release: 2016-06-10 15:10:46
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本文实例讲述了python抽象基类用法。分享给大家供大家参考。具体如下:

定义抽象类,需要使用abc模块,该模块定义了一个元类(ABCMeata),和装饰器 @abstractmethod, @abstractproperty
如果要实例化继承了Foo 的子类,子类必须实现了Foo所有的抽象方法(跟java一样),否则实例化报错。
抽象类不能直接实例化

#!coding=utf-8
from abc import ABCMeta, abstractmethod, abstractproperty
class Foo:
  __metaclass__ = ABCMeta
  @abstractmethod
  #在python3.0中 使用 class Foo(metaclass=ABCMeta)语法
  def spam(self, a, b):
    pass
  @abstractproperty
  def name(self):
    pass
class Bar(Foo):
  def spam(self, a, b):
    print a, b
  def name():
    pass
b = Bar()
b.spam(1,2)
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抽象基类支持对已经存在的类进行注册,使其属于该基类,使用register()方法
向抽象基类注册某个类,对于注册类中的实例,涉及后续基类的类检测操作比如(isinstance, issubclass) 将返回True,向抽象基类注册某个类时,不会检查该类是否实现了任何抽象方法或特性,这种注册过程只会影响类型检查

class Crok(object):
  def spam(self, a, c):
    print "gork.span"
Foo.register(Grok)
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希望本文所述对大家的Python程序设计有所帮助。

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