python 使用__slots__

使用__slots__：

正常情况下,当我们定义了一个class,创建了夜歌class的实例后,我们可以给该梳理绑定任何属性和方法,

给实例绑定一个属性:


class Student(object):
   pass
s=Student()
s.name='aaa'
print s.name



给class 绑定方法:



使用__slots__

class Student(object):
   pass
s=Student()
s.name='aaaa'
s.score='bbbb'
s.age='ccc'
print s.name
print s.score
print s.age


C:Python27python.exe C:/Users/TLCB/PycharmProjects/untitled/mycompany/cookbook/a21.py
aaaa
bbbb
ccc


为了达到限制的目的，Python允许在定义class的时候，定义一个特殊的__slots__变量，来限制该class能添加的属性：


# !/usr/bin/env python
# -*- coding: utf-8 -*-
class Student(object):
    __slots__ = ('name', 'age')  # 用tuple定义允许绑定的属性名称
s=Student()
s.name='aaaa'
s.score='bbbb'
s.age='ccc'
print s.name
print s.score
print s.age


C:Python27python.exe C:/Users/TLCB/PycharmProjects/untitled/mycompany/cookbook/a21.py
Traceback (most recent call last):
  File "C:/Users/TLCB/PycharmProjects/untitled/mycompany/cookbook/a21.py", line 7, in <module>
    s.score='bbbb'
AttributeError: 'Student' object has no attribute 'score'