Python中的迭代器、生成器

代码中需要导入:

from collections import Iterable, Iterator

1. 可迭代(iterable)对象

参考官网链接

class I:
    def __init__(self, v):
        self.v = v

    def __iter__(self):
        return iter([self.v])  # 返回的应该是迭代器对象

i = I(2)
print(isinstance(i, Iterable), isinstance(i, Iterator)) # True False
print(iter(i)) # <list_iterator object at 0x00000000021C8358>

class I:
    def __init__(self, v):
        self.v = v

    def __getitem__(self, item):
        if item > self.v:
            raise IndexError
        return item


i = I(2)
print(isinstance(i, Iterable), isinstance(i, Iterator)) # False False
print(iter(i)) # <iterator object at 0x0000000001DFCD30>

2. 迭代器(iterator)

参考官网链接

class I:
    def __init__(self, v):
        self.v = v

    def __iter__(self):
        return self

    def __next__(self):
        if self.v < 10:
            self.v += 1
            return self.v
        raise StopIteration

i = I(2)
print(isinstance(i, Iterable), isinstance(i, Iterator))  # True True
print(iter(i)) # <__main__.I object at 0x00000000021E0898>

3. 生成器(generator)

参考官网链接

class I:
    def __init__(self, v):
        self.v = v

    def __iter__(self):
        yield 1


i = I(2)
print(isinstance(i, Iterable), isinstance(i, Iterator)) # True False
print(iter(i)) # <generator object I.__iter__ at 0x00000000022204C0>