python之反射 | 易学教程

反射：用字符串数据类型的变量名来访问这个变量的值
反射的方法: getattr hasattr setattr delattr

1、一般的代码编写的方式

class Student:
    def __init__(self,name):
        self.name = name
    def check_course(self):
        print('check_course')
    def choose_course(self):
        print('choose_course')
    def choosed_course(self):
        print('查看已选择的课程')
stu = Student()
num = input('>>>')
if num == 'check_course':
    stu.check_course()
elif num == 'choose_course':
    stu.choose_course()
elif num == 'choosed_course':
    stu.choosed_course()

2、类静态属性类方法静态方法
命名空间.XXX == getattr(命名空间,'XXX')

class Student:
    ROLE = 'STUDENT'
    @classmethod
    def check_course(cls):
        print('查看课程了')

    @staticmethod
    def login():
        print('登录')
# 反射查看属性
print(Student.ROLE)
print(getattr(Student,'ROLE'))

# 反射调用方法
getattr(Student,'check_course')()  # 类方法
getattr(Student,'login')()         # 静态方法

num = input('>>>')
if hasattr(Student,num):
    getattr(Student,num)()

3、对象
方法对象属性

class A():
    def __init__(self,name):
        self.name = name

    def func(self):
        print('in func')

a = A('alex')
print(a.name)
print(getattr(a,'name'))
getattr(a,'func')()

4、模块中的反射

import os   # 别人写好的python代码的结合
# os.rename('__init__.py','init')
# getattr(os,'rename')('init','__init__.py') # == os.rename
rename = os.rename
rename2 = getattr(os,'rename')
rename2('__init__.py','init')  # os.rename('__init__.py','init')
rename('init','init2')          # os.rename('init','init2')

def wahaha():
    print('wahaha')

def qqxing():
    print('qqxing')

反射自己模块中的内容  找到自己当前文件所在的命名空间
wahaha()
qqxing()

import sys
print(sys.modules)
# import 都相当于导入了一个模块，模块哪个导入了 哪个没导入 在我的python解释器里应该记录下来
# 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
# sys.modules 这个方法 表示所有在当前这个python程序中导入的模块
# '__main__': <module '__main__' from 'D:/sylar/python_workspace/day20/4.反射.py'>
print(sys.modules['__main__']) # 显示当前文件所在的系统位置
my_file = sys.modules['__main__']
my_file.wahaha()
my_file.qqxing()
# 'qqxing'
# 'wahaha'
getattr(my_file,'wahaha')()
getattr(my_file,'qqxing')()

# 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')

测试题：

选课系统的代码

根据每个身份对应的类让用户选择能够做的事情

class Manager:
    OPERATE_DIC = [
        ('创造学生账号', 'create_student'),
        ('创建课程', 'create_course'),
        ('查看学生信息', 'check_student_info'),
    ]

    def __init__(self, name):
        self.name = name

    def create_student(self):
        print('创建学生账号')

    def create_course(self):
        print('创建课程')

    def check_student_info(self):
        print('查看学生信息')


class Student:
    OPERATE_DIC = [
        ('查看所有课程', 'check_course'),
        ('选择课程', 'choose_course'),
        ('查看已选择的课程', 'choosed_course')
    ]

    def __init__(self, name):
        self.name = name

    def check_course(self):
        print('check_course')

    def choose_course(self):
        print('choose_course')

    def choosed_course(self):
        print('查看已选择的课程')


def login():
    username = input('user : ')
    password = input('pwd : ')
    with open('userinfo') as f:
        for line in f:
            user, pwd, ident = line.strip().split('|')  # ident = 'Manager'
            if user == username and pwd == password:
                print('登录成功')
                return username, ident


import sys


def main():
    usr, id = login()
    print('user,id :', usr, id)
    file = sys.modules['__main__']
    cls = getattr(file, id)  # Manager = getattr(当前文件,'Manager')
    obj = cls(usr)
    operate_dic = cls.OPERATE_DIC
    while True:
        for num, i in enumerate(operate_dic, 1):
            print(num, i[0])
        choice = int(input('num >>>'))
        choice_item = operate_dic[choice - 1]
        getattr(obj, choice_item[1])()

main()
# l = ['a','b','c']
# for num,i in enumerate(l,1):
#     print(num,i)

# class A:
#     def __init__(self,name):
#         self.name = name
#
# a = A('alex')


# # a.name = 'alex_SB'
# # getattr(a,'name')
# setattr(a,'name','alex_SB')
# print(a.name)
# print(a.__dict__)
# del a.name
# print(a.__dict__)
# delattr(a,'name')
# print(a.__dict__)

来源：CSDN

作者：yunson_Liu

链接：https://blog.csdn.net/baidu_38432732/article/details/103994839

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