python基础----__next__和__iter__实现迭代器协议

#_*_coding:utf-8_*_
__author__ = 'Linhaifeng'
class Foo:
    def __init__(self,x):
        self.x=x

    def __iter__(self):
        return self

    def __next__(self):
        n=self.x
        self.x+=1
        return self.x

f=Foo(3)
for i in f:
    print(i)

简单示范

class Foo:
    def __init__(self,start,stop):
        self.num=start
        self.stop=stop
    def __iter__(self):
        return self
    def __next__(self):
        if self.num >= self.stop:
            raise StopIteration
        n=self.num
        self.num+=1
        return n

f=Foo(1,5)
from collections import Iterable,Iterator
print(isinstance(f,Iterator))

for i in Foo(1,5):
    print(i)

class Fib:
    def __init__(self):
        self._a=0
        self._b=1

    def __iter__(self):
        return self

    def __next__(self):
        self._a,self._b=self._b,self._a + self._b
        return self._a

f1=Fib()

print(f1.__next__())
print(next(f1))
print(next(f1))

for i in f1:
    if i > 100:
        break
    print('%s ' %i,end='')

斐波那契数列

笔记：

from collections import Iterable,Iterator
class Foo:
    def __init__(self,start):
        self.start=start

    def __iter__(self):
        return self

    def __next__(self):
        return 'aSB'


f=Foo(0)
f.__iter__()
f.__next__()

print(isinstance(f,Iterable))
print(isinstance(f,Iterator))

print(next(f)) #f.__next__()
print(next(f)) #f.__next__()
print(next(f)) #f.__next__()


for i in f: # res=f.__iter__() #next(res)
    print(i)



from collections import Iterable,Iterator
class Foo:
    def __init__(self,start):
        self.start=start

    def __iter__(self):
        return self

    def __next__(self):
        if self.start > 10:
            raise StopIteration
        n=self.start
        self.start+=1
        return n

f=Foo(0)

print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))
print(next(f))

for i in f:
    print('====>',i)




class Range:
    '123'
    def __init__(self,start,end):
        self.start=start
        self.end=end

    def __iter__(self):
        return self

    def __next__(self):
        if self.start == self.end:
            raise StopIteration
        n=self.start
        self.start+=1
        return n

for i in Range(0,3):
    print(i)

print(Range.__doc__)


class Foo:
    '我是描述信息'
    pass

class Bar(Foo):
    pass
print(Bar.__doc__) #该属性无法继承给子类

b=Bar()
print(b.__class__)
print(b.__module__)
print(Foo.__module__)
print(Foo.__class__) #?