Evolving the pip list json output

Currently, pip list --format=json produces a json array.

I think it could be valuable for pip list to output additional information, such as an environment object with PEP 608 environment markers, etc. Such a change would require the pip list output to evolve in a backward incompatible way, in this case because of the current array output that would need to be converted to an object.

It is to be noted that such back-ward incompatible changes will probably be very infrequent, since we’ll presumably only want to add new information to the output. An example of backward compatible change is https://github.com/pypa/pip/pull/11097 which adds a metadata property to the list items.

How should such backward-incompatible changes be addressed ?

• with a new format option such as --format=json+v2 ?
• with a new commend such as pip inspect ?

[uranusjr]

I don’t like json+v2 since it implies we’ll lose the prettier json key forever. Perhaps --use-feature=list-json-2022 is a better way to transition?

Introduing pip inspect is a good idea if it can have more use cases, but I can’t think of any right now.

[pfmoore]

I hope we reach that goal one day too.

Actually, it occurred to me that we may even be able to do this right now. I put together a very simple proof of concept and it seems to work. If you put the following script alongside a “lib” directory with pip installed into it (pip install pip --target lib) but with the bin and pip*.dist-info directory removed (so the bundled pip isn’t visible in pip list) then it can be run from any Python interpreter to effectively act as a copy of pip in that environment.

#!/usr/bin/env python

import runpy
import sys
import os

lib = os.path.join(os.path.dirname(__file__), "lib")
sys.path.insert(0, lib)

runpy.run_module("pip", run_name="__main__")

I don’t think it would take much to turn this into a viable “standalone pip” application (I’d mostly just want to set up an executable wrapper for Windows). I’ve done some very basic testing - this would need a lot more real-world testing to make sure there aren’t any problem edge cases, but it basically seems to work.