面向对象--反射

什么是反射?

用字符串数据类型的变量名来访问这个变量的值

反射的应用: 类,对象,模块,反射自己模块的内容

反射的方法:

1.getattr

2.hasattr

3.setattr

4.delattr

类

反射查看属性:

class Student:
    mind="有思想的"
    @classmethod
    def check_course(cls):
        print("查看课程")
    @staticmethod
    def login():
        print("登录")

print(Student.mind)
print(getattr(Student,"mind"))

有思想的
有思想的

反射调用方法:

class Student:
    mind="有思想的"
    @classmethod
    def check_course(cls):
        print("查看课程")
    @staticmethod
    def login():
        print("登录")
print(getattr(Student,"check_course"))
getattr(Student,"check_course")()

<bound method Student.check_course of <class '__main__.Student'>>
查看课程

class Student:
    mind="有思想的"
    @classmethod
    def check_course(cls):
        print("查看课程")
    @staticmethod
    def login():
        print("登录")
num=input(">>>")
getattr(Student,num)()

输入:check_course
返回结果:查看课程

输入任意值
返回结果:报错

这时我们就可以进行异常处理了hasatter

class Student:
    mind="有思想的"
    @classmethod
    def check_course(cls):
        print("查看课程")
    @staticmethod
    def login():
        print("登录")
num=input(">>>")
if hasattr(Student,num):
getattr(Student,num)()

对象

方法  对象属性

class A():
    def __init__(self,name):
        self.name=name
    def func(self):
        print("func....")
a=A("asdf")
print(a.name)
print(getattr(a,"name"))

结果:
asdf
asdf

class A():
    def __init__(self,name):
        self.name=name
    def func(self):
        print("func....")
a=A("asdf")
print(a.func())
getattr(a,"func")()

结果:
func....
func....

模块

import os
os.rename("__init__.py",'init')
getattr(os,"name")("__init__.py",'init')

注: 

    getattr(os,"name") == os.rename

import os
r=os.rename
g=getattr(os,"name")
r("__init__.py","init") 
g("__init__.py","init")

注:

os.rename('__init__.py','init')

getattr(os,"name")('init','init2')

反射自己模块中的内容

class A:
    print("A...")
class B:
    print("B...")
A()
B()

执行自己模块的函数只需要A()就可以,但是当前找不到自己当前文件所在的命名空间.

class A:
    print("A...")
class B:
    print("B...")
# import 都相当于导入了一个模块
import sys
# import sys 是一个模块,这个模块里的所有的方法都是和python解释器相关的
# print(sys.modules)
结果:
A...
B...
{'sys': <module 'sys' (built-in)>, 'builtins': <module 'builtins' (built-in)>, '_frozen_importlib': <module '_frozen_importlib' (frozen)>, '_imp': <module '_imp' (built-in)>, '_thread': <module '_thread' (built-in)>, '_warnings': <module '_warnings' (built-in)>, '_weakref': <module '_weakref' (built-in)>, 'zipimport': <module 'zipimport' (built-in)>, '_frozen_importlib_external': <module '_frozen_importlib_external' (frozen)>, '_io': <module 'io' (built-in)>, 'marshal': <module 'marshal' (built-in)>, 'nt': <module 'nt' (built-in)>, 'winreg': <module 'winreg' (built-in)>, 'encodings': <module 'encodings' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\encodings\__init__.py'>, 'codecs': <module 'codecs' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\codecs.py'>, '_codecs': <module '_codecs' (built-in)>, 'encodings.aliases': <module 'encodings.aliases' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\encodings\aliases.py'>, 'encodings.utf_8': <module 'encodings.utf_8' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\encodings\utf_8.py'>, '_signal': <module '_signal' (built-in)>, '__main__': <module '__main__' from 'E:/chenwei/陈伟learning/week5/day1.py'>, 'encodings.latin_1': <module 'encodings.latin_1' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\encodings\latin_1.py'>, 'io': <module 'io' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\io.py'>, 'abc': <module 'abc' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\abc.py'>, '_abc': <module '_abc' (built-in)>, 'site': <module 'site' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site.py'>, 'os': <module 'os' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\os.py'>, 'stat': <module 'stat' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\stat.py'>, '_stat': <module '_stat' (built-in)>, 'ntpath': <module 'ntpath' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\ntpath.py'>, 'genericpath': <module 'genericpath' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\genericpath.py'>, 'os.path': <module 'ntpath' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\ntpath.py'>, '_collections_abc': <module '_collections_abc' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\_collections_abc.py'>, '_sitebuiltins': <module '_sitebuiltins' from 'C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\_sitebuiltins.py'>, 'sitecustomize': <module 'sitecustomize' from 'D:\PyCharm 2018.1.3\helpers\pycharm_matplotlib_backend\sitecustomize.py'>}
# sys.modules 这个方法 表示所有在当前这个python程序中导入的模块
# print(sys.modules['__main__'])
结果:
A...
B...
my_file = sys.modules['__main__']
my_file.A()
my_file.B()
getattr(my_file,'A')()
getattr(my_file,'B')()
结果:
A...
B...

总结:

 反射
 hasattr,getattr
 类名.名字
     getattr(类名,'名字')
 对象名.名字
     getattr(对象,'名字')
 模块名.名字
     import 模块
     getattr(模块,'名字')
 自己文件.名字
     import sys
     getattr(sys.modules['__main__'],'名字')