How to ensure that the Python file is correctly executed in a nested folder structure?

Question

I am trying to run a Python file from a codebase, and have created a minimal example to explain the issue that I am facing.

foo
├── bar
│   ├── burp
│   │   └── cache.py
│   ├── __init__.py
│   └── pyro.py
└── __init__.py

The file foo/bar/pyro.py contains

def explosion():
    print('boom boom')

The file foo/bar/burp/cache.py contains

from bar.pyro import explosion
def setup():
    print('setting things up')

setup()
explosion()

When I execute foo/bar/burp/cache.py, I face the error as below.

$ python3 bar/burp/cache.py
Traceback (most recent call last):
  File "bar/burp/cache.py", line 1, in <module>
    from bar.pyro import explosion
ModuleNotFoundError: No module named 'bar'

However the program runs fine while running in the interpreter.

$ python3
Python 3.8.10 (default, Nov  7 2024, 13:10:47)
>>> exec(open('bar/burp/cache.py').read())
setting things up
boom boom

What causes this difference and how can I resolve the error in the first approach?

Pratyush Goutam · Accepted Answer · 2024-12-24 07:46:20Z

1

To solve this you can run your Python script with the PYTHONPATH set to the foo directory, allowing Python to find bar.pyro from within foo:

$ PYTHONPATH=foo python3 bar/burp/cache.py

This tells Python to treat the foo directory as part of the module search path.

answered Dec 24, 2024 at 7:46

Pratyush Goutam

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Mario Mateaș · Accepted Answer · 2024-12-24 08:10:32Z

0

You could use relative imports. In your cache.py file:

from ..pyro import explosion
def setup():
    print('setting things up')

setup()
explosion()

and run your Python script as a module, starting from the first folder outside your top level directory, using:

python -m foo.bar.burp.cache

edited Dec 24, 2024 at 8:10

answered Dec 24, 2024 at 7:45

Mario Mateaș

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