day27-python之迭代器协议
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2023-12-24 20:08:39
1.item系列方法 2.slots属性 3.内置方法 4.描述符 5.描述符优先级 6.改变对象的字符串显示 7.析构方法 8.自定义格式化方法format 9.迭代器协议 10.迭代器协议实现斐波那契数列 ......
1.item系列方法
# class foo:
# def __getitem__(self, item):
# print('getitem',item)
# 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)
#
class foo:
def __getitem__(self, item):
print('getitem',item)
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)
f1 = foo()
print(f1.__dict__)
f1.name = 'egon'
# f1['name'] = 'egon'
f1['age'] = 18
# print(f1.__dict__)
# del f1.name
# print(f1.age)
# del f1['name']
# print(f1.__dict__)
print(f1['age'])
raise stopasynciteration
# f1=foo()
# print(f1.__dict__)
# # f1.name='egon' #---->setattr-------->f1.__dict__['name']='egon'
# f1['name']='egon'#--->setitem--------->f1.__dict__['name']='egon'
# f1['age']=18
#
# print('===>',f1.__dict__)
#
# # del f1.name
# # print(f1.__dict__)
# #
# # print(f1.age)
# del f1['name']
# print(f1.__dict__)
#
# print(f1['age'])
# raise s
2.slots属性
class foo:
__slots__ = ['name','age']
f1 = foo()
f1.name = 'egon'
print(f1.name)
# class foo:
# __slots__=['name','age'] #{'name':none,'age':none}
# __slots__='name' #{'name':none,'age':none}
# f1=foo()
# f1.name='egon'
# print(f1.name)
# f1.age=18 #--->setattr----->f1.__dict__['age']=18
f1.age = 18
# print(f1.__dict__)
print(foo.__slots__)
print(f1.__slots__)
f1.name = 'egon'
f1.age = 17
print(f1.name)
print(f1.age)
# print(f1.__dict__)
# print(foo.__slots__)
# print(f1.__slots__)
# f1.name='egon'
# f1.age=17
# print(f1.name)
# print(f1.age)
# f1.gender='male'
# f1.gender = 'male'
f2 = foo()
print(f2.__slots__)
f2.name = 'alex'
f2.age = 18
print(f2.name)
print(f2.age)
# f2=foo()
# print(f2.__slots__)
# f2.name='alex'
# f2.age=18
# print(f2.name)
# print(f2.age)
3.内置方法
class foo:
x = 1
def __init__(self,y):
self.y = y
def __getattr__(self, item):
print('------> from getattr:你找的属性不存在')
def __setattr__(self, key, value):
print('-----> from setattr')
self.__dict__[key] = value
def __delattr__(self, item):
print('-----> from delattr')
self.__dict__.pop(item)
f1 = foo(10)
# class foo:
# x=1
# def __init__(self,y):
# self.y=y
#
# def __getattr__(self, item):
# print('----> from getattr:你找的属性不存在')
#
#
# def __setattr__(self, key, value):
# print('----> from setattr')
# # self.key=value #这就无限递归了,你好好想想
# # self.__dict__[key]=value #应该使用它
#
# def __delattr__(self, item):
# print('----> from delattr')
# # del self.item #无限递归了
# self.__dict__.pop(item)
#
#
# f1=foo(10)
# f1.x
4.描述符
# class foo:
# def __get__(self, instance, owner):
# print('===>get方法')
# def __set__(self, instance, value):
# print('===>set方法',instance,value)
# instance.__dict__['x']=value #b1.__dict__
# def __delete__(self, instance):
# print('===>delete方法')
class foo:
def __get__(self, instance, owner):
print('===>get方法')
def __set__(self, instance, value):
print('===>set方法',instance,value)
instance.__dict__['x'] = value
def __delete__(self, instance):
print('===>delete方法')
class bar:
x = foo()
def __init__(self,n):
self.x = n
b1 = bar(10)
print(b1.__dict__)
b1.x = 11111111111
print(b1.__dict__)
# class bar:
# x=foo() #在何地？
# def __init__(self,n):
# self.x=n #b1.x=10
# b1=bar(10)
# print(b1.__dict__)
# b1.x=11111111111111111
# print(b1.__dict__)
#
b1.y = 111111111111111111111111
print(b1.__dict__)
print(bar.__dict__)
# b1.y=11111111111111111111111111111111111111
# print(b1.__dict__)
# print(bar.__dict__)
b1 = bar()
b1.x = 1
# del b1.x
print(b1.x)
#在何时？
# b1=bar()
# b1.x
#
# b1.x=1
#
# del b1.x
# print(b1.x)
#
# b1.x=1
# print(b1.__dict__)
#
# del b1.x
5.描述符优先级
# class foo:
# def __get__(self, instance, owner):
# print('===>get方法')
#
# def __set__(self, instance, value):
# print('===>set方法',instance,value)
#
# def __delete__(self, instance):
# print('===>delete方法')
# class foo:
# def __get__(self, instance, owner):
# print('===>get方法')
# def __set__(self, instance, value):
# print('===>set方法',instance,value)
# # instance.__dict__['x']=value #b1.__dict__
# def __delete__(self, instance):
# print('===>delete方法')
#
#
# class bar:
# x=foo() #在何地？
# print(bar.x)
# bar.x=1
# print(bar.__dict__)
# print(bar.x)
# print(bar.__dict__)
# b1=bar()
# b1.x #get
# b1.x=1 # set
# del b1.x # delete
# b1=bar()
# bar.x=111111111111111111111111111111111111111
# b1.x
#
# del bar.x
# b1.x
class foo:
def __get__(self, instance, owner):
print('===>get方法')
def __delete__(self, instance):
print('===>delete方法')
class bar:
x = foo()
def __getattr__(self, item):
print('-------->')
b1 = bar()
# b1.x = 1
print(b1.__dict__)
# class foo:
# def __get__(self, instance, owner):
# print('===>get方法')
#
#
# # def __delete__(self, instance):
# # print('===>delete方法')
#
#
# class bar:
# x=foo() #在何地？
# def __getattr__(self, item):
# print('----->')
#
# b1=bar()
# b1.x=1
# print(b1.__dict__)
# b1.xxxxxxxxxxxxxxxxxxxxxxx
6.改变对象的字符串显示
# l=list('hello')
#
# print(l)
# file=open('test.txt','w')
# print(file)
# class foo:
# def __init__(self,name,age):
# self.name=name
# self.age=age
# def __str__(self):
# return '名字是%s 年龄是%s' %(self.name,self.age)
#
# f1=foo('egon',18)
# print(f1) #str(f1)--->f1.__str__()
#
# x=str(f1)
# print(x)
#
# y=f1.__str__()
# print(y)
class foo:
def __init__(self,name,age):
self.name = name
self.age = age
def __str__(self):
return '折是str'
def __repr__(self):
return '名字是%s 年龄是%s' %(self.name,self.age)
f1 = foo('as',12)
f1.__repr__()
# class foo:
# def __init__(self,name,age):
# self.name=name
# self.age=age
# # def __str__(self):
# # return '折是str'
# def __repr__(self):
# return '名字是%s 年龄是%s' %(self.name,self.age)
#
# f1=foo('egon',19)
# #repr(f1)---->f1.__repr__()
# print(f1) #str（f1）---》f1.__str__()------>f1.__repr__()
7.析构方法
# class foo:
# def __init__(self,name):
# self.name=name
# def __del__(self):
# print('我执行啦')
#
# f1=foo('alex')
#
# # del f1 #删除实例会触发__del__
# del f1.name #删除实例的属性不会触发__del__
# print('--------------------->')
#
# #程序运行完毕会自动回收内存，触发__del__
class foo:
def __init__(self,name):
self.name = name
def __del__(self):
print('我执行啦')
f1 = foo('andy')
# del f1.name
8.自定义格式化方法format
# x='{0}{0}{0}'.format('dog')
#
# print(x)
# class date:
# def __init__(self,year,mon,day):
# self.year=year
# self.mon=mon
# self.day=day
# d1=date(2016,12,26)
#
# x='{0.year}{0.mon}{0.day}'.format(d1)
# y='{0.year}:{0.mon}:{0.day}'.format(d1)
# z='{0.mon}-{0.day}-{0.year}'.format(d1)
# print(x)
# print(y)
# print(z)
# x='{0.year}{0.mon}{0.day}'.format(d1)
# y='{0.year}:{0.mon}:{0.day}'
# z='{0.mon}-{0.day}-{0.year}'
# format_dic={
# 'ymd':'{0.year}{0.mon}{0.day}',
# 'm-d-y':'{0.mon}-{0.day}-{0.year}',
# 'y:m:d':'{0.year}:{0.mon}:{0.day}'
# }
format_dic = {
'ymd':'{0.year}{0.mon}{0.day}',
'm-d-y':'{0.mon}-{0.day}-{0.year}',
'y:m:d':'{0.year}:{0.mon}:{0.day}'
}
class date:
def __init__(self,year,mon,day):
self.year = year
self.mon = mon
self.day = day
def __format__(self, format_spec):
print('我执行啦')
print('--->',format_spec)
if not format_spec or format_spec not in format_dic:
format_spec = 'ymd'
fm = format_dic[format_spec]
return fm.format(self)
d1 = date(2016,12,13)
print(format(d1,'ymd'))
print(format(d1,'y:m:d'))
print(format(d1,'m-d-y'))
print(format(d1,'m-d:y'))
# class date:
# def __init__(self,year,mon,day):
# self.year=year
# self.mon=mon
# self.day=day
# def __format__(self, format_spec):
# print('我执行啦')
# print('--->',format_spec)
# if not format_spec or format_spec not in format_dic:
# format_spec='ymd'
# fm=format_dic[format_spec]
# return fm.format(self)
# d1=date(2016,12,26)
# # format(d1) #d1.__format__()
# # print(format(d1))
# print(format(d1,'ymd'))
# print(format(d1,'y:m:d'))
# print(format(d1,'m-d-y'))
# print(format(d1,'m-d:y'))
# print('===========>',format(d1,'asdfasdfsadfasdfasdfasdfasdfasdfasdfasdfasdfasdfasd'))
print('=============>',format(d1,'assddd'))
9.迭代器协议
# class foo:
# def __init__(self,n):
# self.n=n
# def __iter__(self):
# return self
#
# def __next__(self):
# if self.n == 13:
# raise stopiteration('终止了')
# self.n+=1
# return self.n
class foo:
def __init__(self,n):
self.n = n
def __iter__(self):
return self
def __next__(self):
if self.n == 13:
raise stopiteration('终止了')
self.n+=1
return self.n
f1 = foo(10)
print(f1.__next__())
print(f1.__next__())
# l=list('hello')
# for i in l:
# print(i)
# f1=foo(10)
# # print(f1.__next__())
# # print(f1.__next__())
# # print(f1.__next__())
# # print(f1.__next__())
#
# for i in f1: # obj=iter(f1)------------>f1.__iter__()
# print(i) #obj.__next_()
for i in f1:
print(i)
10.迭代器协议实现斐波那契数列
# class fib:
# def __init__(self):
# self._a=1
# self._b=1
#
# def __iter__(self):
# return self
# def __next__(self):
# if self._a > 100:
# raise stopiteration('终止了')
# self._a,self._b=self._b,self._a + self._b
# return self._a
class fib:
def __init__(self):
self._a = 1
self._b = 1
def __iter__(self):
return self
def __next__(self):
if self._a > 100:
raise stopiteration('终止了')
self._a,self._b=self._b,self._a+self._b
return self._a
f1 = fib()
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
# f1=fib()
# print(next(f1))
# print(next(f1))
# print(next(f1))
# print(next(f1))
# print(next(f1))
# print('==================================')
# for i in f1:
# print(i)