zoukankan      html  css  js  c++  java
  • Python的hasattr(),getattr(),setattr()

    今天读到源码时遇到了setattr()和getattr()两方法,给忘了,重新回顾一下吧!

    1. hasattr(object, name)

      判断object里是否有name属性,有就返回True,没有则返回False.

    class MyClass(object):
        name = 'jack'
        age = '22'
    
    
    obj = MyClass()
    print(hasattr(obj, 'name'))  # True
    print(hasattr(MyClass, 'age'))  # True
    print(hasattr(obj, 'gender'))  # False

    2. getattr(object, name, [default])

      用来获取object的属性或方法,有就打印出来.  没有就打印默认值,若是没有设置默认值则报错

    class MyClass(object):
        name = 'jack'
        age = '22'
    
        def func(self):
            return 'hello world!!!'
    
    
    obj = MyClass()
    
    print(getattr(MyClass, 'name'))  # jack
    print(getattr(obj, 'age'))  # 22
    print(getattr(MyClass, 'func'))  # <function MyClass.func at 0x000001ACDE9A9AE8>
    print(getattr(obj, 'func'))  # <bound method MyClass.func of <__main__.MyClass object at 0x000001D1505D01D0>>
    # print(getattr(MyClass, 'func1'))  # 没有设置默认值,找不到方法会报错: AttributeError: type object 'MyClass' has no attribute 'func1'
    print(getattr(MyClass, 'func1', None))  # 设置了默认值None,找不到就会返回默认值: None
    print(getattr(MyClass, 'func')('self'))  # hello world!!!
    print(getattr(obj, 'func')())  # hello world!!!
    
    

    3.  setattr(object, key, value)

      用来对object的属性key赋值value. 若是key存在,则更新value的值. 若key不存在,则先创建属性key再对其赋值value.

    class MyClass(object):
        name = 'jack'
        age = '22'
    
    
    obj = MyClass()
    
    setattr(MyClass, 'name', 'tom')
    print(getattr(MyClass, 'name'))  # tom
    
    setattr(obj, 'age', 28)
    print(getattr(obj, 'age'))  # 28
    
    setattr(MyClass, 'gender', 'male')
    print(getattr(MyClass, 'gender'))  # male
    print(getattr(obj, 'gender'))  # male
    
    setattr(obj, 'hobby', 'skating')
    print(obj, 'hobby')  # <__main__.MyClass object at 0x00000209F5070630> hobby
    print(MyClass, 'hobby')  # <class '__main__.MyClass'> hobby

      三个方法一起用

    class MyClass(object):
        name = 'jack'
        age = '22'
    
    
    # 判断Myclass是否有gender属性,有则打印,没有则添加
    def if_attr(gender='male'):
        if hasattr(MyClass, 'gender'):
            return getattr(MyClass, 'gender')
        return setattr(MyClass, 'gender', gender)
    
    
    if_attr(gender='female')
    print(getattr(MyClass, 'gender'))  # female
  • 相关阅读:
    连Action Bar都不会 你能说你学过 Android?
    Java设计模式 —— 单例模式
    删库跑路 + 比特币勒索?我的MySQL被黑客攻破了
    微信小程序 带参二维码 纯Java实现
    【个人简介】关于博主&阅读指南
    微信小程序 获取 手机验证码 短信验证码 后端功能实现解析
    Handler processing failed; nested exception is java.lang.NoSuchMethodError:
    腾讯云服务器备案全流程 40天备案的血与泪
    [总结]2020年2月 OI学习/刷题记录
    [Luogu P5680][GZOI2017]共享单车
  • 原文地址:https://www.cnblogs.com/huangqihui/p/10145855.html
Copyright © 2011-2022 走看看