python 可迭代对象 迭代器 生成器

一个对象若要用for 循环 则需实现def __iter__(self, item) 或def __iter__(self, item)方法

可迭代对象 实现了def __iter__(self, item)方法  

迭代器  实现了def __iter__(self, item)和def __next__(self)方法  

迭代器一定是可迭代对象 可迭代对象不一定是迭代器

from collections.abc import Iterable,Iterator
class Student():
    def __init__(self,studentList):
        self.studentList=studentList
        self._index=0
    def __getitem__(self, item):
        return self.studentList[item]
    def __iter__(self):
        return iter(self.studentList)
    def __next__(self):
        stu=self.studentList[self._index]
        self._index+=1
        return stu


if __name__=='__main__':

    stus=Student(['aa','bb','cc','ee'])
    for stu in stus:
        print(stu)
    print(isinstance(stus,Iterable))
    print(isinstance(stus, Iterator))
    print(next(stus))