from collections import Iterable
from collections import Iterator
import time


class Classmate(object):
    current_num = 0

    def __init__(self):
        self.name = list()

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

    # 如果想要一个对象成为一个可迭代的对象，即可以使用for 那么必须实现__iter__方法
    def __iter__(self):
        # 返回这个对象必须有__next__方法
        return ClassIterator(self)


class ClassIterator(object):
    def __init__(self, obj):
        self.obj = obj

    def __iter__(self):
        pass

    def __next__(self):
        if self.obj.current_num<len(self.obj.name):
            ret = self.obj.current_num
            self.obj.current_num += 1
            return self.obj.name[ret]
        else:
            raise StopIteration


classmate = Classmate()
classmate.add("老王")
classmate.add("张三")

# 判断Classmate是否是可迭代类型
print("判断classmate是否可迭代", isinstance(classmate, Iterable))
classmate_iterator = iter(classmate)
print("判断classmate_iterator是否是可迭代对象", isinstance(classmate_iterator, Iterator))
print(next(classmate_iterator))
for n in classmate:
    # 每调用一次都会调用classmate的__iter__方法返回值对象的__next__方法
    print(n)
    time.sleep(1)

E:\python_project\NetWork\venv\Scripts\python.exe E:/python_project/NetWork/协程/__init__.py
判断classmate是否可迭代 True
判断classmate_iterator是否是可迭代对象 True
老王
张三

Process finished with exit code 0

改进版的迭代器

from collections import Iterable
from collections import Iterator
import time


class Classmate(object):
    current_num = 0

    def __init__(self):
        self.name = list()

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

    # 如果想要一个对象成为一个可迭代的对象，即可以使用for 那么必须实现__iter__方法
    def __iter__(self):
        # 返回这个对象必须有__next__方法
        return self

    def __next__(self):
        if self.current_num < len(self.name):
            ret = self.current_num
            self.current_num += 1
            return self.name[ret]
        else:
            raise StopIteration


classmate = Classmate()
classmate.add("老王")
classmate.add("张三")

# 判断Classmate是否是可迭代类型
print("判断classmate是否可迭代", isinstance(classmate, Iterable))
classmate_iterator = iter(classmate)
print("判断classmate_iterator是否是可迭代对象", isinstance(classmate_iterator, Iterator))
print(next(classmate_iterator))
for n in classmate:
    # 每调用一次都会调用classmate的__iter__方法返回值对象的__next__方法
    print(n)
    time.sleep(1)