如何使用相对导入在包内运行模块? [英] How to run a module inside a package, using relative imports?
问题描述
此问题特定于 PyDev. 包结构如下所示:
app
├── __init__.py
├── sub1
│ ├── __init__.py
│ └── mod1.py
└── sub2
├── __init__.py
└── mod2.py
mod1.py 模块:
from __future__ import print_function
def f():
print('It works!')
mod2.py 模块:
from __future__ import absolute_import
from ..sub1 import mod1
if __name__ == '__main__':
mod1.f()
一切从 shell 运行得很好，python -m app.sub2.mod2 命令打印:
It works!
正如预期的那样，一切都很好.(from __future__ import absolute_import 行似乎没有效果:我可以将其注释掉，一切仍然正常.)
as expected, all is fine. (The from __future__ import absolute_import line seems to have no effect: I can comment it out and everything still works just fine.)
如果我在 PyDev IDE 中单击 mod2 并尝试 Run As > Python Run，我得到
If I click on mod2 in the PyDev IDE and try to Run As > Python Run, I get
ValueError: Attempted relative import in non-package
这并不奇怪，因为 -m 开关默认没有打开.如果我编辑 mod2 的运行/调试设置: Arguments > VM Arguments 并在此处添加 -m ；-m 最有可能传递给 python 解释器，但现在我得到:
which is not surprising as the -m switch is not turned on by default. If I edit the Run/Debug settings for mod2: Arguments > VM Arguments and add -m here; the -m is most likely passed to the python interpreter but now I get:
/usr/bin/python: Import by filename is not supported.
from __future__ import absolute_import 行似乎没有效果；我是否将其注释掉并不重要；我使用的是 Python 2.7.
The from __future__ import absolute_import line seems to have no effect; it does not matter whether I comment it out or not; I am using Python 2.7.
我现在没有想法.
在 PyDev 中，如何在使用相对进口?
In PyDev, how can I run a module inside a package that uses relative imports?
我应该如何更改设置一次(全局)，以便每当我尝试在包内运行一个模块，PyDev 做正确的事吗?(也就是说，我不必为每个单独指定设置我希望运行的模块.)
How should I change the settings once (globally) such that whenever I try to run a module inside a package, PyDev does the right thing? (That is, I don't have to individually specify the settings for each module that I wish to run.)
开发者亲自确认在PyDev中目前还无法实现；我已经为它开了一张票.
The developer in person confirmed that it is not possible in PyDev yet; I have opened a ticket for it.
更新:截至 2016 年 12 月 2 日，问题已解决，请参阅已接受的答案.
UPDATE: As of Dec 2, 2016, the issue is resolved, see the accepted answer.
推荐答案
在 PyDev 5.4.0 中，现在有一个使用 -m 标志运行的选项(它将通过其常规名称导入模块，而不是像以前那样__main__ 这样相对导入就可以在那里工作).
In PyDev 5.4.0, there's now an option to run using the -m flag (which will import the module through its regular name and not as it was __main__ so that relative imports will work there).
您可以在以下位置启用它:Preferences >PyDev >运行(即:这将为所有运行启用它——也许将来会有一个选项可以每次运行都启用它，但现在它为所有启动设置了全局).
You can enable it at: Preferences > PyDev > Run (i.e.: this will enable it for all runs -- maybe in the future there'll be an option to make it per run, but for now it's set globally for all launches).
原答案:
问题是您的主模块中有相对导入，PyDev 使用 python path/to/file_to_execute.py 而不是 python -m my.module 执行文件>.
The problem is that you have relative imports in your main module and PyDev executes the file with python path/to/file_to_execute.py instead of python -m my.module.
一个简单的修复是做一个单独的主模块，然后从该模块导入一个 main() 函数并运行它(尽管再次:它不能在模块中以 __main__ (发生这种情况是因为模块名为 __main__，因此无法解析相对导入，因为它实际上并未使用可用于解析相对导入的名称导入).
A simple fix is doing a separate main module which in turn imports a main() function from that module and runs it (although again: it can't have relative imports in the module executed as __main__ (this happens because the module is called __main__ and thus cannot resolve a relative import because it wasn't actually imported with a name which can be used to resolve the relative import).
另一个修复是更改启动配置以在 VM 参数中添加 '-m my.module'(转到运行 > 运行配置来执行此操作 - 但您必须这样做对于您要运行的每个主要模块，包括单元测试).
Another fix would be changing the launch configuration to add the '-m my.module' in the VM arguments (go to run > run configurations to do that -- but you have to do that for each main module you want to run, including unit-tests).
最后一个修复是更改 PyDev 本身(因此，请在 PyDev 跟踪器中为此创建一个票证:https://www.brainwy.com/tracker/PyDev/ -- 或提交拉取请求，这样可以更快地添加该功能;) )
And the last fix would be changing PyDev itself (so, please create a ticket for that in the PyDev tracker: https://www.brainwy.com/tracker/PyDev/ -- or submit a pull request, which would make adding that feature much faster ;) )
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