python 动态添加属性及方法及“__slots__的作用”

1.动态添加属性

class Person(object):

    def __init__(self, newName, newAge):

        self.name = newName

        self.age = newAge

laowang = Person("老王", 10000)

print(laowang.name)

print(laowang.age)

laowang.addr = "北京...."

print(laowang.addr)

laozhao = Person("老赵", 18)

#print(laozhao.addr)

Person.num = 100

print(laowang.num)

print(laozhao.num)

2.动态添加方法

#!/usr/local/bin/python3

# -*- coding:utf-8 -*-

import types

class Person(object):

    def __init__(self,name,age):

        self.name = name

        self.age = age

def eat(self):

    print('---%s正在吃----' %self.name)

p1 = Person('p1',100)

#p1.eat = eat             #右边的eat指向eat 函数内存地址，赋值给p1对象的eat属性

#p1.eat()                 #这样调用会报错

########那样怎么添加呢？？？？

##在开头导入模块types,再用如下方法：

p1.eat = types.MethodType(eat,p1)

p1.eat()

#####用法#################

>>> import types
>>> help(types.MethodType)
Help on class method in module builtins:

class method(object)
| method(function, instance)

##############__slots__ 的作用################

In [18]: class Person(object):

    ...:     __slots__ = ("name","age")       #####只能添加元祖中定义了的属性，不在元组内的不行

    ...:

In [19]: p1 = Person()

In [20]: p1.name = 'haha'

In [21]: p1.addr = 'beijing'

---------------------------------------------------------------------------

AttributeError                            Traceback (most recent call last)

<ipython-input-21-be5d7a142f3a> in <module>()

----> 1 p1.addr = 'beijing'

AttributeError: 'Person' object has no attribute 'addr'