Python 類的高階特性

可以繫結變數和方法

如果需要繫結的方法來呼叫類內部的成員,該方法的第乙個引數為self

動態繫結的變數與方法只作用於該物件

>>> 

class
user_info
(object):
... 
pass
... 
>>> 
deffoo
():...     print('foo')
... 
>>> 
deffoo_class
(self):
...     print(self.name)
... 
>>> u = user_info()
>>> u.name = 'root'
>>> u.pwd = 'admin'
>>> u.foo = foo
>>> u.foo_class = foo_class
>>> u.name
'root'
>>> u.pwd
'admin'
>>> u.foo()
foo>>> u.foo_class()
traceback (most recent call last):
file "", line 1, in
typeerror: foo_class() missing 1 required positional argument: 'self'

靜態成員是屬於類的, 不屬於物件

>>> 

class
user_info
(object):
name = 'aaa'
>>> user_info.name
'aaa'
>>> a = user_info()
>>> a.name
'aaa'
>>> b = user_info()
>>> b.name
'aaa'
>>> a.name = 'bbb'
>>> a.name
'bbb'
>>> b.name
'aaa'
>>> user_info.name
'aaa'
>>> user_info.name = 'ccc'
>>> a.name
'bbb'
>>> b.name
'ccc'
>>>

比如在給物件賦值時寫錯了變數名,就會變成動態繫結

>>> 

class
user_info
(object):
name = 'aaa'
>>> a = user_info()
>>> a.nama = 'bbb'
#本意是給name賦值,結果繫結了乙個nama的變數

>>> class cls_demo(object):

...     __slots__ = ('name', 'pwd') # 只允許繫結 name 和 pwd
... 
>>> demo1 = cls_demo()
>>> demo1.user = 'root'
traceback (most recent call last):
file "", line 1, in
attributeerror: 'cls_demo' object has no attribute 'user'
>>> demo1.name = 'admin'
>>> demo1.name
'admin'

>>> 

class
user_info
(object):
... 
def__init__
(self, name, pwd):
...         self.__name = name
...         self.__pwd = pwd
... 
... 
@property
... 
defname
(self):
# 特性, 唯讀
... 
return self.__name
... 
@name.setter
... 
defname
(self, val):
# 特性, 只寫
...         self.__name = val
... 
>>> u = user_info('root', 'admin')
>>> print(u.name)
root
>>> u.name = 'aaa'
# u.name實際是呼叫的上面的name方法,這種方式使得python**變得優雅
>>> print(u.name)
aaa>>>

in的時候會呼叫 iter

for的時候會不斷呼叫 next

>>> 

import random
>>> 
class
user_info
(object):
... 
def__init__
(self, name, pwd):
...         self.__name = name
...         self.__pwd = pwd
...         self.__loop = 10
... 
... 
def__iter__
(self):
...         print('__iter__')
...         self.__loop = 10
# 規定迭代次數
... 
return self         
... 
... 
def__next__
(self):
...         print('__next__')
...         ret = random.randint(1, 1000)
...         self.__loop -= 1
... 
ifnot self.__loop:
... 
raise stopiteration()   # 停止迭代
... 
return ret
... 
>>> u = user_info('root', 'admin')
>>> 
for i in u:    # for會接收到stopiteration的異常從而退出迴圈
...     print(i)
... 
__iter__
__next__
542__next__
498__next__
483__next__
353__next__
156__next__
893__next__
624__next__
682__next__
541__next__
>>>

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