class Person:
    city = ‘zhengzhou‘
    def show_info(self):
        print(‘info---‘)
    @classmethod
    def show_city(cls):
        print(‘city---‘)
# 使用类调用属性
if hasattr(Person,‘city‘):  #先判断有没有，有再获取，防止没有该属性而报错
    res = getattr(Person,‘city‘)
    print(res)
# 使用类调用方法
if hasattr(Person,‘show_city‘): #先判断有没有，有再获取，防止没有该方法而报错
    res2 = getattr(Person,‘show_city‘)  #得到一个方法地址
    res2()  #调用方法

# 对象调用方法
jcc = Person()
if hasattr(jcc,‘show_info‘):
    fun = getattr(jcc,‘show_info‘)
    fun()

import time
inp = input(‘>>>‘)
t1 = getattr(time,inp)
print(t1())

import sys
year = 2018
def jcc():
    print(‘jcc‘)
print(sys.modules[‘__main__‘])  #得到本模块
getattr(sys.modules[‘__main__‘],‘year‘)     #反射得到变量
fun = getattr(sys.modules[‘__main__‘],‘jcc‘)
fun()

class Person():
    @staticmethod
    def getinfo(name,age):
        print(‘%s,%s‘%(name,age))
fun = getattr(Person,‘getinfo‘)
fun(‘jcc‘,‘18‘)     #参数直接传

class Person():
    def __init__(self,name):
        self.name = name
    def __getitem__(self, item):
        print(‘getitem‘)
        return self.__dict__[item]
    def __setitem__(self, key, value):
        print(‘setitem‘)
        self.__dict__[key] = value
    def __delitem__(self, key):
        print(‘delitem‘)
        self.__dict__.pop(key)
    def __delattr__(self, item):
        print(‘delattr‘)
        self.__dict__.pop(item)


p = Person(‘jcc‘)
print(p[‘name‘])    #自动调用__getitem__
p[‘age‘] = 16       #自动调用__setitem__
del p.age           #自定调用__delattr__
del p[‘age‘]        #自动调用__delitem__

class Person():
    def __init__(self,name):
        print(‘__init__‘)
        self.name = name
    def __new__(cls, *args, **kwargs):
        print(‘__new__‘)
        return object.__new__(cls)
p = Person(‘jcc‘)   #先自动调用__new__，再自动调用__init__

利用__new__方法 生成一个单例模式
class Person():
    def __init__(self,name):
        self.name = name
    def __new__(cls, *args, **kwargs):
        if not hasattr(cls,‘instance‘):
            cls.instance = object.__new__(cls)
        return cls.instance
p1 = Person(‘jcc‘)
p2 = Person(‘dudu‘)
print(p1 ==p2)

class Person():
    def __init__(self,name):
        self.name = name
    def __new__(cls, *args, **kwargs):
        print(‘__new__‘)
        return object.__new__(cls)
    def __call__(self, *args, **kwargs):
        print(‘__call__‘)
p = Person(‘jcc‘)   #自动调用__new__方法
p()     #自动调用__call__方法

class A:
    def __init__(self):
        self.a = 1
        self.b = 2
    def __eq__(self,obj):
        print(‘__eq__‘)
        if  self.a == obj.a and self.b == obj.b:
            return True
a = A()
b = A()
print(a == b)   #自动调用__eq__方法
__hash__
class A:
    def __init__(self):
        self.a = 1
        self.b = 2

    def __hash__(self):
        print(‘__hash__‘)
        return hash(str(self.a)+str(self.b))
a = A()
print(hash(a))      #自动调用__hash__方法