Python 如何跟踪要导入的库（目录）？

Question

I have two slightly different branches of Python 3 code on my computer. I am frequently switching back and forth between them. Both contain slightly modified files and directories that are named the same way. The code in each directory imports code from a subdirectory, eg "from ldm.util import instantiate_from_config", where "ldm" is a subdirectory of the directory I'm currently in, and "util.py" is a file in "ldm."

Python keeps getting confused when I import and using the "util.py" and "ldm" directory from the other branch. Neither branch is on the Windows PATH or PYTHONPATH. I can trick Python by temporarily renaming the directory I don't want to use, but I want to understand: how is Python remembering that this other directory exists to go import it? How can I tell Python that if a folder is a subdirectory of the folder I'm currently in, that's the version I want it to import?

Answer 1

I think I found the answers:

1. "The first thing Python will do is look up the name abc in sys.modules. This is a cache of all modules that have been previously imported."
2. "The syntax of a relative import depends on the current location as well as the location of the module, package, or object to be imported." So it needs a "." beforehand to tell it to use something from the current location. Example: "from.subpackage1.module5 import function2" from https://realpython.com/absolute-vs-relative-python-imports/