迭代器协议

1# 一个简单的列表（可迭代对象）
2colors = ["Red", "Green", "Blue"]
3
4# 从列表中获取迭代器
5color_cursor = iter(colors)
6
7# 手动获取项目
8first_item = next(color_cursor)
9print(f"First: {first_item}")
10
11second_item = next(color_cursor)
12print(f"Second: {second_item}")
13
14third_item = next(color_cursor)
15print(f"Third: {third_item}")

1numbers = [10, 20, 30]
2number_stream = iter(numbers)
3
4print("Starting manual loop...")
5
6while True:
7    try:
8        # 请求下一个项目
9        item = next(number_stream)
10        print(f"Processing: {item}")
11    except StopIteration:
12        # 当迭代器为空时执行此块
13        print("Iterator is empty. Stopping loop.")
14        break

1text = "Hi"
2text_iterator = iter(text)
3
4# 检查迭代器对象
5print(f"Methods in iterator: {dir(text_iterator)}")
6
7# 直接调用特殊方法（与 next(text_iterator) 相同）
8print(text_iterator.__next__())
9print(text_iterator.__next__())
10
11# 下一次调用将引发 StopIteration
12# text_iterator.__next__()

1data = ["A", "B", "C"]
2
3# 为同一列表创建两个独立的迭代器
4iter_1 = iter(data)
5iter_2 = iter(data)
6
7# 移动 iter_1 前进
8print(f"Iterator 1: {next(iter_1)}") 
9
10# 移动 iter_2 前进（它从开头开始）
11print(f"Iterator 2: {next(iter_2)}") 
12
13# 再次移动 iter_1
14print(f"Iterator 1: {next(iter_1)}")
15
16# iter_2 仍停留在 'B'
17print(f"Iterator 2: {next(iter_2)}")