Hi 🙂 I'm super excited that my company is moving to pants 🎉 i am looking for a way to run multiple versions of the black linter in my repo (i need an older version for parts that are written in python 2.7 and the new version for what's written in newer python versions). i can't seem to find a solution that's not "hacky". any ideas on how i can achieve this or if this has built in support can anyone point me to the relevant documentation?

I've never needed to do something like that, but would something like multiple resolves work? https://www.pantsbuild.org/blog/2022/05/25/multiple-lockfiles-python#pantss-hybrid-approach-granular-resolves

I've read about multiple resolves. I don't understand how to use it with the

install_from_resolve

in

[black]

for example

Hi! Alas there is no way to run multiple different versions of black in the same Pants run (with the same config). What you can do is have a separate

pants.py27.toml

config file that overrides the relevant settings in the regular pants.toml, and then invoke Pants on just the Python 2.7 targets with

--pants-configfiles=pants.py27.toml

.

🤦‍♂️ I forgot that black's versioning is handled by us in

pants.toml

😆

The difficulty is that install_from_resolve wants a single resolve, but essentially you need different versions of Black installed. I'm on mobile and can't test, but having a single resolve with 2 sets of requirements conditional on the python version (something like

black==1.2.3; python<3

) might work? I think that will cause both versions of black to be registered in the lockfile, and the right one will be picked by the interpreter constraints of the python files. Not sure though.

@happy-kitchen-89482 have you tried aliasing the config files option?. I recall issues with aliasing certain bootstrap options and since the alias definition is in a config file it wouldn’t surprise me if there’s some rough edges there..

Ah, no, I didn't actually try this out

yea

@careful-address-89803, Although I am unfamiliar with the conditions syntax adding the condition as you suggested resulted in an error

Invalid requirement 'black==21.12b0;python<3' in foo/black-requirements.txt at line 1: Parse error at "';python<'": Expected string_end

As for the solution suggested by @happy-kitchen-89482, I want both versions to run at the same time (running the lint/build command one) if I understand correctly your solution requires me to have to run pants twice and that's not exactly what I'm looking for

It should be

python_version<3

.. not sure that'll do it though, as black still seems to require a Py 3.x also when working on Py 2.7 code..