April 2023
Intermediate to advanced
769 pages
25h 16m
Chinese
Content preview from 流畅的Python（第2版）
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492
｜
第
17
章
LookupError
ValueError
AssertionError
ArithmeticError
SystemError
ReferenceError
MemoryError
BufferError
Warning
GeneratorExit
SystemExit
KeyboardInterrupt
你或许已经明白了，不过我还是想继续坚持婴儿学步原则，再嵌套一层
for
循环，到达第
3
层。程序的其余部分没有变化，示例
17-31
只给出了
sub_tree
生成器。
示例
17-31
tree/step4/tree.py
中的
sub_tree
生成器
def sub_tree(cls):
for sub_cls in cls.__subclasses__():
yield sub_cls.__name__, 1
for sub_sub_cls in sub_cls.__subclasses__():
yield sub_sub_cls.__name__, 2
for sub_sub_sub_cls in sub_sub_cls.__subclasses__():
yield sub_sub_sub_cls.__name__, 3
通过示例
17-31
可以清晰地看到处理模式：一层
for
循环对应一层子类。如果一层
for
循
环产出第
N
层子类，那么下一层循环就进入第
N
+1
层。
17.11.1
节讲过
，我们可以把驱动生成器的嵌套
for
循环替换成
yield ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.