44、class類：

一、類定義的一般形式：

1、簡單的形式：實例化對象沒有自己獨有的數據屬性。

>>> class fistclass():

... data1 = 'hello world' ### ==>這是類的數據屬性或類成員屬性。

... def printdata(self): ###==>這是類的方法，而且這里至少有一個參數self！！！

... print('nihao%s' %self.data1)

...

>>> class1 = fistclass() ##==>類實例化

>>> class1.

class1.__class__( class1.__format__( class1.__le__( class1.__reduce_ex__( class1.__weakref__

class1.__delattr__( class1.__ge__( class1.__lt__( class1.__repr__( class1.data1

class1.__dict__ class1.__getattribute__( class1.__module__ class1.__setattr__( class1.printdata(

class1.__dir__( class1.__gt__( class1.__ne__( class1.__sizeof__(

class1.__doc__ class1.__hash__( class1.__new__( class1.__str__(

class1.__eq__( class1.__init__( class1.__reduce__( class1.__subclasshook__(

>>> class1.data1 ##類數據屬性調用

'hello world'

>>> class1.printdata() ##類的方法的調用

nihaohello world

2、定義對象獨有的數據屬性：

>>> class seclass():

... data1 = 'hello seclass'

... def setdata(self,x):

... self.str1 = x

... def printdata(self):

... print(self.str1)

...

>>> ins1 = seclass()

>>> ins1.

ins1.__class__( ins1.__format__( ins1.__le__( ins1.__reduce_ex__( ins1.__weakref__

ins1.__delattr__( ins1.__ge__( ins1.__lt__( ins1.__repr__( ins1.data1

ins1.__dict__ ins1.__getattribute__( ins1.__module__ ins1.__setattr__( ins1.printdata(

ins1.__dir__( ins1.__gt__( ins1.__ne__( ins1.__sizeof__( ins1.setdata(

ins1.__doc__ ins1.__hash__( ins1.__new__( ins1.__str__(

ins1.__eq__( ins1.__init__( ins1.__reduce__( ins1.__subclasshook__(

>>> ins1.data1

'hello seclass'

>>> ins1.setdata('abc')

>>> ins1.printdata()

abc

>>> ins2 = seclass()

>>> ins2.data1

'hello seclass'

>>> ins2.setdata('xy')

>>> ins2.printdata()

xy

3、__init__()方法：

創建實例時，python會自動調用類中的__init__方法，以隱性的為實例提供屬性。

__init__稱之為構造器。

如果類中沒有定義__init__方法，則實例之初僅僅是創建一個簡單的名稱空間。

>>> class thirdclass():

... data3 = 'hello thirdclass'

... def __init__(self,who):

... self.name = who

...

>>> ins3 = thirdclass('lucy')

>>> ins3.

ins3.__class__( ins3.__format__( ins3.__le__( ins3.__reduce_ex__( ins3.__weakref__

ins3.__delattr__( ins3.__ge__( ins3.__lt__( ins3.__repr__( ins3.data3

ins3.__dict__ ins3.__getattribute__( ins3.__module__ ins3.__setattr__( ins3.name

ins3.__dir__( ins3.__gt__( ins3.__ne__( ins3.__sizeof__(

ins3.__doc__ ins3.__hash__( ins3.__new__( ins3.__str__(

ins3.__eq__( ins3.__init__( ins3.__reduce__( ins3.__subclasshook__(

>>> ins3.data3

'hello thirdclass'

>>> ins3.name

'lucy'

4、__dict__:

>>> ins3.__dict__ 實例的屬性

{'name': 'lucy'}

>>> thirdclass.__dict__ 類的屬性。

mappingproxy({'data3': 'hello thirdclass', '__init__': , '__dict__': , '__module__': '__main__', '__doc__': None, '__weakref__': })

5、類中的可用變量：

>>> class c1():

... var1 = 'hello c1' ###==>類的靜態變量！！！！

... def __init__(self,who):

... self.insdata = who ###==>實例變量。

... self.name = '123' ###==>局部變量：只屬于這個方法。

...

>>> ins1 = c1(12)

>>> ins1.

ins1.__class__( ins1.__format__( ins1.__le__( ins1.__reduce_ex__( ins1.__weakref__

ins1.__delattr__( ins1.__ge__( ins1.__lt__( ins1.__repr__( ins1.insdata

ins1.__dict__ ins1.__getattribute__( ins1.__module__ ins1.__setattr__( ins1.name

ins1.__dir__( ins1.__gt__( ins1.__ne__( ins1.__sizeof__( ins1.var1

ins1.__doc__ ins1.__hash__( ins1.__new__( ins1.__str__(

ins1.__eq__( ins1.__init__( ins1.__reduce__( ins1.__subclasshook__(

>>> ins1.name

'123'

>>> ins1.var1

'hello c1'

>>> ins1.insdata

12

6、類的繼承：python允許多重繼承，屬性搜索方法：從左往右，從下往上。

>>> class PClass(object):

... gender = 'male'

... def __init__(self,who):

... self.name = who

...

>>> class CClass(PClass):

... def displayinfo(self):

... print(self.gender,self.name)

...

>>> ins1 = CClass('lucy')

>>> ins1.

ins1.__class__( ins1.__format__( ins1.__le__( ins1.__reduce_ex__( ins1.__weakref__

ins1.__delattr__( ins1.__ge__( ins1.__lt__( ins1.__repr__( ins1.displayinfo(

ins1.__dict__ ins1.__getattribute__( ins1.__module__ ins1.__setattr__( ins1.gender

ins1.__dir__( ins1.__gt__( ins1.__ne__( ins1.__sizeof__( ins1.name

ins1.__doc__ ins1.__hash__( ins1.__new__( ins1.__str__(

ins1.__eq__( ins1.__init__( ins1.__reduce__( ins1.__subclasshook__(

>>> ins1.gender

'male'

>>> ins1.name

'lucy'

>>> ins1.displayinfo()

male lucy