python为什么看不到我的模块？

Question

I have a file structure like this:

/package/main.py
/package/__init__.py
/package/config_files/config.py
/package/config_files/__init__.py

I'm trying to dynamically import config.py from main.py based on a command line argument, something like this:

#!/usr/bin/env python
from importlib import import_module

cmd_arguments = sys.argv
config_str = cmd_arguments[1]    
config = import_module(config_str, 'config_files')

but it complains breaks with ModuleNotFoundError: No module named 'default_config' . Similar code in ipython does not suffer the same issue, when called from /package

If there is a better way to load a package at run time via user input, I'm open to suggestions.

Answer 1

You are trying to import from a nested package, so use the full package name:

config = import_module(config_str, 'package.config_files')

Alternatively, use a relative import, and set the second argument to package :

config = import_module('.config_files.{}'.format(config_str), 'package')

This is more secure, as now the config_str string can't be used to 'break out' of the config_files sub package.

You do want to strip dots from user-provided names (and, preferably, limit the name to valid Python identifiers only).