class A:pass
class B(A):pass
a = A()
print(isinstance(a,A))
print(issubclass(B,A))
print(issubclass(A,B))>>>
True
True
False

class A:def func(self):print('in func')a = A()
a.name = 'alex'
a.age = 63ret = getattr(a,'name')  # 通过变量名的字符串形式取到的值
print(ret)
print(a.__dict__)变量名 = input('>>>')   # func
print(getattr(a,变量名))
print(a.__dict__[变量名])》》》
alex
{'name': 'alex', 'age': 63}
>>>age
63
63

class A:def func(self):print('in func')a = A()a.func()
ret = getattr(a,'func')
print(ret)                      #不加括号只能打印一个内存地址
ret()》》》
in func
<bound method A.func of <__main__.A object at 0x00000250C461E668>>
in func

class A:price = 20@classmethoddef func(cls):print('in func')print(getattr(A,'price'))》》》
20

#需要使用到装饰器    classmethod     staticmethodclass A:price = 20@classmethoddef func(cls):print('in func')if hasattr(A,'func'):getattr(A,'func')()》》》
in func

#新建一个my.py
#内容
day = 'Monday'  # 周一def wahaha():print('wahahaha')class C:pass#在另一个py文件里运行
import my
print(my.day)
print(getattr(my,'day'))》》》
Monday
Monday

#新建一个my.py
#内容
day = 'Monday'  # 周一def wahaha():print('wahahaha')class C:pass#在另一个py文件里运行

getattr(my,'wahaha')()》》》
wahahaha

#新建一个my.py
#内容
day = 'Monday'  # 周一def wahaha():print('wahahaha')class C:pass#在另一个py文件中运行import my
print(getattr(my,'C')())》》》
<my.C object at 0x0000029F28E9E080>

# time
# asctime
import time
print(getattr(time,'time')())
print(getattr(time,'asctime')())》》》
1516608195.0811734
Mon Jan 22 16:03:15 2018

def qqxing():print('qqxing')
year = 2018
import sys
print(sys.modules['__main__'].year)
print(getattr(sys.modules['__main__'],'year'))》》》
2018
2018

def qqxing():print('qqxing')
year = 2018
import sysgetattr(sys.modules['__main__'],'qqxing')()
变量名 = input('>>>')
print(getattr(sys.modules[__name__],变量名))》》》
qqxing
>>>year
2018

import time
print(time.strftime('%Y-%m-%d %H:%M:S'))
print(getattr(time,'strftime')('%Y-%m-%d %H:%M:S'))》》》
2018-01-22 16:08:S
2018-01-22 16:08:S

class A:name = 'xiaoming'def run(self):return 'gogogo'
a = A()
print(a.run())
print(hasattr(a,'name'))     #判断对象是否有  name  属性
print(hasattr(a,'run'))      #判断对象是否有  run  方法
print(hasattr(A,'run'))      #判断类是否有  run  属性
print(hasattr(A,'rn')) 》》》
gogogo
True
True
True
False

class A:pass
a = A()
setattr(a,'name','nezha')
setattr(A,'name','alex')
print(A.name)
print(a.name)

class A:pass
a = A()
setattr(a,'name','nezha')
setattr(A,'name','alex')delattr(a,'name')
print(a.name)
delattr(A,'name')
print(a.name)》》》
alex
Traceback (most recent call last):File "D:/Python学习/Python/学习资料/学习视频/day27/2.反射.py", line 122, in <module>print(a.name)
AttributeError: 'A' object has no attribute 'name'

#_*_coding:utf-8_*_

format_dict={'nat':'{obj.name}-{obj.addr}-{obj.type}',#学校名-学校地址-学校类型'tna':'{obj.type}:{obj.name}:{obj.addr}',#学校类型:学校名:学校地址'tan':'{obj.type}/{obj.addr}/{obj.name}',#学校类型/学校地址/学校名
}
class School:def __init__(self,name,addr,type):self.name=nameself.addr=addrself.type=typedef __repr__(self):return 'School(%s,%s)' %(self.name,self.addr)def __str__(self):return '(%s,%s)' %(self.name,self.addr)def __format__(self, format_spec):# if format_specif not format_spec or format_spec not in format_dict:format_spec='nat'fmt=format_dict[format_spec]return fmt.format(obj=self)s1=School('oldboy1','北京','私立')
print('from repr: ',repr(s1))
print('from str: ',str(s1))
print(s1)'''
str函数或者print函数--->obj.__str__()
repr或者交互式解释器--->obj.__repr__()
如果__str__没有被定义,那么就会使用__repr__来代替输出
注意:这俩方法的返回值必须是字符串,否则抛出异常
'''
print(format(s1,'nat'))
print(format(s1,'tna'))
print(format(s1,'tan'))
print(format(s1,'asfdasdffd'))

class B:def __str__(self):return 'str : class B'def __repr__(self):return 'repr : class B'b=B()
print('%s'%b)
print('%r'%b)%s和%r

class A:def __init__(self,name):self.name = namedef __call__(self):'''打印这个对象中的所有属性:return:'''for k in self.__dict__:print(k,self.__dict__[k])
a = A('alex')()    #后面的括号可以直接让__call__(self)函数执行
》》》
name alex

class A:def __init__(self):self.a = 1self.b = 2def __len__(self):return len(self.__dict__)
a = A()
print(len(a))

class Foo:def __init__(self,name,age,sex):self.name = nameself.age = ageself.sex = sexdef __getitem__(self, item):if hasattr(self,item):return self.__dict__[item]def __setitem__(self, key, value):self.__dict__[key] = valuedef __delitem__(self, key):del self.__dict__[key]f = Foo('wangming',38,'男')
print(f['name'])
f['hobby'] = '男'
print(f.hobby,f['hobby'])
del f.hobby      # object 原生支持  __delattr__
del f['hobby']   # 通过自己实现的
print(f.__dict__)

class A:def __init__(self):self.x = 1print('in init function')def __new__(cls, *args, **kwargs):print('in new function')return object.__new__(A, *args, **kwargs)a = A()
print(a.x)》》》
in new function
in init function
1

#单例模式
#一个类 始终 只有 一个 实例
#当你第一次实例化这个类的时候 就创建一个实例化的对象
#当你之后再来实例化的时候 就用之前创建的对象class Singleton:def __new__(cls, *args, **kw):if not hasattr(cls, '_instance'):cls._instance = object.__new__(cls, *args, **kw)return cls._instanceone = Singleton()
two = Singleton()two.a = 3
print(one.a)
# 3
# one和two完全相同,可以用id(), ==, is检测
print(id(one))
# 29097904
print(id(two))
# 29097904
print(one == two)
# True
print(one is two)单例模式单例模式

class A:def __init__(self):self.a = 5self.b = 2def __eq__(self,obj):if  self.a == obj.a and self.b == obj.b:return True
a = A()
b = A()
print(a.a)
print(a.b)
print(b.a)
print(b.b)
print(a == b)》》》
5
2
5
2
True