Set JULIA_PYTHONCALL_EXE=$CONDA_PREFIX/bin/python on activate

[mkitti]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[isuruf]

why?

[mkitti]

@cjdoris , I would appreciate your thoughts on setting the environment variable when we have julia installed by conda.

export JULIA_PYTHONCALL_EXE="$CONDA_PREFIX/bin/python"

[mkitti]

why?

Otherwise, PythonCall.jl via CondaPkg.jl would create a new conda environment. Presumably one would want to default to using the current conda environment if we're already managing Julia in that conda environment rather than create a new one.

[mkitti]

See https://discourse.julialang.org/t/how-to-use-pythoncall-with-a-previous-conda-environment/87419/8

[cjdoris]

Seems reasonable. Beware that this means PythonCall will not use CondaPkg, and therefore all the dependencies you need must already be installed into the pre-existing Conda environment. But I assume this is the intention anyway.

You probably also want to set JULIA_CONDAPKG_BACKEND=Null, which will prevent other things that depend on CondaPkg from installing Python dependencies.