Python之迭代器

1.如果有重载__iter__方法则表示类是一个Iterable

2.如果有重载__next__方法则表示类是一个Iterator

3.可以使用isinstance(obj, Iterable)和isinstance(obj, Iterator)来判断一个实例是否是Iterable和Iterator

from collections import Iterable
from collections import Iterator
import time


class MyIterable:
    """
    类的注释
    """
    def __init__(self):
        self.names = list()
        self.__ind = 0

    def add(self, name):
        self.names.append(name)

    def __iter__(self):
        # return MyIterator(self)
        return self

    def __next__(self):
        print('return from MyIterable::__next__')
        if len(self.names) > self.__ind:
            ret = self.names[self.__ind]
            self.__ind += 1
            return ret
        else:
            raise StopIteration


# class MyIterator():
#     """
#     类的注释
#     """
#     def __init__(self, iterable):
#         self.iterable = iterable
#         self.__ind = 0
#
#     # def __iter__(self):
#     #     pass
#
#     def __next__(self):
#         print('return from MyIterator::__next__')
#         if len(self.iterable.names) > self.__ind:
#             ret = self.iterable.names[self.__ind]
#             self.__ind += 1
#             return ret
#         else:
#             raise StopIteration


def main():
    iterable = MyIterable()
    iterable.add('python')
    iterable.add('cpp')
    iterable.add('csharp')

    # iterator = MyIterator()

    # print(isinstance(iterable, Iterable))
    # print(isinstance(iterator, Iterator))

    # print(next(iterator))

    for name in iterable:
        print(name)
        time.sleep(1)


if __name__ == '__main__':
    main()