在Python中导入深度嵌套的模块 [英] Importing deeply nested modules in Python

问题描述

考虑以下Python 3.6中的情况:

Consider the following case in Python 3.6:

basepackage
    |---__init__.py
    |---package
            |---__init__.py
            |---subpackage
                    |---__init__.py
                    |---module.py

重要细节:在basepackage.package.__init__.py内有:

from basepackage.package.subpackage.module import AClass as AliasedClass

现在，让我们在要使用的basepackage.package.subpackage.module.py中说:

Now, let's say inside basepackage.package.subpackage.module.py we want to use:

import basepackage.package.subpackage.module as aliased_module [1]

import basepackage.package.subpackage.module as aliased_module [1]

结果是:

AttributeError: module 'basepackage' has no attribute 'package'

具有堆栈跟踪，列出了以下罪魁祸首语句(按以下顺序):

with a stack trace listing following culprit statements (in the below order):

from basepackage.package.subpackage.module import AClass as AliasedClass
import basepackage.package.subpackage.module as aliased_module

但是如果要使用[1]代替:

But if instead of [1] one'd like to use:

from basepackage.package.subpackage import module as aliased_module [2]

from basepackage.package.subpackage import module as aliased_module [2]

然后一切正常.

[1]与[2]有何不同，以致前者导致错误而后者没有错误?

How is [1] so much different than [2] that the former results in an error and the latter not?

推荐答案

要使第一个选项(import basepackage.package.subpackage.module as aliased_module)起作用，必须满足以下条件:

For the first option (import basepackage.package.subpackage.module as aliased_module) to work, these conditions have to be met:

• basepackage/__init__.py必须包含类似于from . import package的行(名称package必须在此basepackage/__init__.py文件中定义)
• basepackage/package/__init__.py必须包含类似于from . import subpackage
的行
• basepackage/package/subpackage/__init__.py必须包含类似于from . import module
的行

• basepackage/__init__.py has to contain a line similar to from . import package (the name package has to be defined inside this basepackage/__init__.py file)
• basepackage/package/__init__.py has to contain a line similar to from . import subpackage
• basepackage/package/subpackage/__init__.py has to contain a line similar to from . import module

注意:__init__.py文件中的import语句也可以是绝对的，而不是相对路径.

Note: the import statements inside the __init__.py files can also be absolute instead of relative paths.

对于第二个选项(from basepackage.package.subpackage import module as aliased_module)，只要每个__init__.py文件都存在，则每个级别上都有空的__init__.py文件就足够了.

For the second option (from basepackage.package.subpackage import module as aliased_module), it is enough if there are empty __init__.py files at each level, as long as these __init__.py files exist.

这篇关于在Python中导入深度嵌套的模块的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！