6.4.3 多重路径中的包 Packages in Multiple Directories

Packages support one more special attribute, __path__. This is initialized to be a list containing the name of the directory holding the package's __init__.py before the code in that file is executed. This variable can be modified; doing so affects future searches for modules and subpackages contained in the package.

包支持一个另为特殊的变量， __path__ 。在包的 __init__.py 文件代码执行之前，该变量初始化一个目录名列表。该变量可以修改，它作用于包中的子包和模块的搜索功能。

While this feature is not often needed, it can be used to extend the set of modules found in a package.

这个功能可以用于扩展包中的模块集，不过它不常用。