March 2022
Intermediate to advanced
522 pages
13h 52m
Chinese
Content preview from Python语言及其应用（第2版）
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176
｜
第
11
章
└
critters
└
rougarou.py
如果
north
和
south
均位于模块搜索路径内，则可以导入这些模块，就好像它们仍然位于单
一目录的包中那样。
from critters import wendigo, rougarou
11.2.4
模块和对象
什么时候该把代码放入模块？什么时候该把代码放入对象？
两者在许多方面看起来很相似。对于包含名为
stuff
的内部数据的对象或模块
thing
，其
数据可以使用
thing.stuff
访问。
stuff
可以在创建模块或类时定义，也可以随后赋值。
模块中的所有类、函数和全局变量都可以在外部访问。对象可以使用属性和双下划线命名
方式隐藏或控制对于其数据特性的访问。
这意味着可以这样做：
>>> import math
>>> math.pi
3.141592653589793
>>> math.pi = 3.0
>>> math.pi
3.0
我们刚刚是把这台计算机上的数学工具毁掉了吗？不是。这不会影响
Python
的
math
模块。
我们只是修改了程序所导入的
math
模块代码副本中的
pi
值，程序结束之后，一切改动就
都消失无踪了。
程序导入的模块只有一份副本，即便多次导入。你可以用它来保存导入该模块的代码感兴
趣的全局内容。这就像是类，同样只有一份副本，但可以由此创建多个对象。
11.3 Python
标准库
Python
的著名主张之一是“自备电池”
2
——
一个庞大的标准模块库，可用于完成大量实用
任务。标准库被分开存放，以免造成核心语言臃肿。当你着手编写 ...
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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.