python面向对象（七）属性方法的添加

​ 通常情况下，当我们定义了一个class，创建了一个class的实例后，我们可以给该实例绑定任何属性和方法，这就是动态语言的灵活性。下来我就讲下添加属性和方法，同时也将下限值添加属性方法。

添加属性

​ 给一个实例添加属性和方法时，只有对象能使用，对类添加方法和属性时，为类属性和类方法

>>> class Peopre(object):
	"""docstring for Peopre"""
	def __init__(self):
		pass

... ... ... ... ...
>>> p=Peopre()
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x02B1B6F0>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>})
>>> p.__dict__
{}

#  -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
# 对实例添加属性
>>> p.name='张三'
>>> p.name
'张三'
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x02B1B6F0>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>})

#  -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
# 对类添加属性，添加的为类属性
>>> Peopre.name='name'
>>> Peopre.age='12'
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x02B1B6F0>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>, 'name': 'name', 'age': '12'})

>>> p1=Peopre()
>>> p1.name
'name'
>>> p1.age
'12'
>>> p.name
'张三'

添加方法

>>> class Peopre(object):
	"""docstring for Peopre"""
	def __init__(self):
		pass
... ... ... ...
>>> def hi():
		print("你好")
... ...
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x0327E810>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>})

#  -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
# 添加的方法为类方法
>>> Peopre.hi=hi
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x0327E810>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>, 'hi': <function hi at 0x0327E858>})
>>> Peopre.hi
<function hi at 0x0327E858>
>>> Peopre.hi()
你好
>>> def hello():
... 	print("hello!")
...
>>> p = Peopre()
>>> p.hi
<bound method hi of <__main__.Peopre object at 0x032722B0>>
>>> p.hi()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: hi() takes 0 positional arguments but 1 was given

#  -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
# 添加的为普通方法
>>> p.hello = hello
>>> p.hello()
hello!
>>> p.__dict__
{'hello': <function hello at 0x0327E8A0>}
>>>

删除属性、方法

删除的方法:

• del 对象.属性名
• delattr(对象, "属性名")

>>> class Peopre(object):
	"""docstring for Peopre"""
	def __init__(self, name):
		self.name = name
	def hi(self):
		print("我的名字是:%s"%self.name)
... ... ... ... ... ...
>>> p = Peopre("张三")
>>> p.hi()
我的名字是:张三
>>> p.__dict__
{'name': '张三'}
>>> del(p.name)
>>> p.__dict__
{}
#   删除方法
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x02D2E858>, 'hi': <function Peopre.hi at 0x02D2E810>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>})
>>> def hello():
... 	print("你好")
...
>>> Peopre.hello = hello
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x02D2E858>, 'hi': <function Peopre.hi at 0x02D2E810>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>, 'hello': <function hello at 0x0110D660>})
>>> del(Peopre.hello)
>>> Peopre.__dict__
mappingproxy({'__module__': '__main__', '__doc__': 'docstring for Peopre', '__init__': <function Peopre.__init__ at 0x02D2E858>, 'hi': <function Peopre.hi at 0x02D2E810>, '__dict__': <attribute '__dict__' of 'Peopre' objects>, '__weakref__': <attribute '__weakref__' of 'Peopre' objects>})
>>>

__slots__

​ 限制该class能添加的属性. 但__slots__定义的属性仅对当前类起作用，对继承的子类是不起作用的.

>>> class Peopre(object):
	"""docstring for Peopre"""
	__slots__ = ("name","age")
... ... ...
>>> p = Peopre
>>> p = Peopre()
>>> p.name= "张三"
>>> p.age= 14
>>> p.height = 170
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Peopre' object has no attribute 'height'
#   对继承的子类是不起作用的
>>> class Test(Peopre):
		pass

... ... ...
>>> t = Test()
>>> t.height = 170
>>>