如何在另一个文件夹中导入 Python 模块，无需相对导入和编辑 PYTHONPATH

Question

This is my folder structure:

.
├── main.py
├── formats
│   ├── __init__.py
│   └── writer.py
└── misc
    ├── __init__.py
    └── util.py

In main.py , I can import util.py using:

from misc.util import sth

However, I can't import util.py in writer.py , using the above statement, and this command:

python formats/writer.py

Now the simplest solution is to mess with the PYTHONPATH : a simple export PYTHONPATH=. will do it. However, I don't like doing so, and don't like relative import. What are my options now?

Answer 1

The import mechanism is based on PYTHONPATH.

When you run python main.py , then the directory containing main.py is in PYTHONPATH, so all other packages there are importable as well.

When you run python formats/writer.py , then the formats directory is in PATHONPATH and its parent directory is not, so you cannot import modules and packages which are not in formats .

What you can do, is run writer module, but have the root directory in PATHONPATH and you can do that without even messing with environment variables:

cd /directory/in/which/main.py/is
python -m formats.writer

Unlike python formats/writer.py , which changes PYTHONPATH and runs writer.py , this keeps the default PYTHONPATH (current directory) and tells Python to look within that path for a module named formats.writer and run that as the main module.