Python 礼仪 : Importing Modules

Question

假设我有两个 Python 模块:

module1.py:

import module2
def myFunct(): print "called from module1"

module2.py:

def myFunct(): print "called from module2"
def someFunct(): print "also called from module2"

如果我导入 module1，重新导入 module2 还是只引用 module1.module2 更好？

例如(someotherfile.py):

import module1
module1.myFunct() # prints "called from module1"
module1.module2.myFunct() # prints "called from module2"

我也可以这样做:module2 = module1.module2。现在，我可以直接调用 module2.myFunct()。

但是，我可以将 module1.py 更改为:

from module2 import *
def myFunct(): print "called from module1"

现在，在 someotherfile.py 中，我可以这样做:

import module1
module1.myFunct() # prints "called from module1"; overrides module2
module1.someFunct() # prints "also called from module2"

此外，通过导入 *，help('module1') 显示了 module2 中的所有函数。

另一方面，(假设 module1.py 使用 import module2)，我可以这样做:someotherfile.py:

 import module1, module2
 module1.myFunct() # prints "called from module1"
 module2.myFunct() # prints "called from module2"

同样，礼仪和实践哪个更好？再次引入module2，还是只引用module1的引入？

Answer 1

引用PEP 8 style guide :

When importing a class from a class-containing module, it's usually okay to spell this:

from myclass import MyClass
from foo.bar.yourclass import YourClass

If this spelling causes local name clashes, then spell them

import myclass
import foo.bar.yourclass

强调我的。

不要使用module1.module2；您依赖于 module1 的内部实现细节，稍后可能会更改它使用的导入内容。您可以直接导入 module2，除非模块作者另有说明，否则请这样做。

您可以使用 __all__ convention使用 from modulename import * 限制从模块导入的内容； help() 命令也支持该列表。列出您在 __all__ 中显式导出的名称有助于清理 help() 文本表示:

The public names defined by a module are determined by checking the module’s namespace for a variable named __all__; if defined, it must be a sequence of strings which are names defined or imported by that module. The names given in __all__ are all considered public and are required to exist. If __all__ is not defined, the set of public names includes all names found in the module’s namespace which do not begin with an underscore character ('_'). __all__ should contain the entire public API. It is intended to avoid accidentally exporting items that are not part of the API (such as library modules which were imported and used within the module).