python 反射

class Student:
    """
    1.tom是实例化的对象，反射：对象的属性、方法
    2.Student是类，反射：类的静态属性和类方法
    3.反射方法：获取的值要加()，有参数时，要添加参数
    4.hasattr()用于判断和getattr()可以看成夫妻档，一般成对出现
    """
    country = ‘china‘

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

    def info(self, new_grade):
        if self.grade < new_grade:
            return "恭喜"
        else:
            return "遗憾"

    @classmethod
    def coun(cls, new_country):
        Student.country = new_country


tom = Student(‘tom‘, 70)
if hasattr(tom, ‘name‘):        # 对象属性反射
    print(getattr(tom, ‘name‘))     # 结果：tom    

if hasattr(tom, ‘info‘):
    ret = getattr(tom, ‘info‘)      # 对象方法的反射
    print(ret(80))          # 结果：恭喜       

if hasattr(Student, ‘coun‘):
    ret = getattr(Student, ‘coun‘)      # 静态属性/类属性的反射
    ret(‘USA‘)

if hasattr(Student, ‘country‘):     # 类方法的反射
    print(getattr(Student, ‘country‘))      # 结果：USA

import sys
"""
1.反射自己的模块，实质是.py文件命令、函数的反射
2.sys.modules[__name__]，获取当前文件对象
3.python一切皆对象
"""
name = ‘tom‘


def output():
    return "Hello World!"


# print(sys.modules[__name__])    # 获取当前文件，python一切皆对象
if hasattr(sys.modules[__name__], ‘name‘): 
    print(getattr(sys.modules[__name__], ‘name‘))   # 结果：tom
if hasattr(sys.modules[__name__], ‘output‘):
    ret = getattr(sys.modules[__name__], ‘output‘)      #
    print(ret())       # 结果：Hello World!

"""
1.setattr()，Sets the named attribute on the given object to the specified value
2.delattr(), Deletes the named attribute from the given object.
"""


class Test:
    def sb(self):
        return ‘sb‘


t1 = Test()
setattr(t1, ‘name‘, ‘china_lead‘)   # 设置对象t1的属性name和值china_lead
if hasattr(t1, ‘name‘):
    print(getattr(t1, ‘name‘))      # 结果：china_lead
try:
    delattr(t1, ‘name‘)     # 通过反射删除对象的属性
    getattr(t1, ‘name‘)
except Exception as error:
    print(‘result: %s‘ % error)     # result: ‘Test‘ object has no attribute ‘name‘