fix: make python3 dep just a default

[yajo]

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When trying to build a package that had python3 = nixpkgs.python311, I got an error similar to:

       Definition values:
       - In `/nix/store/...-source/nix/modules/dream2nix/default': <derivation python3-3.11.4>
       - In `/nix/store/...-source/modules/dream2nix/core/paths': <derivation python3-3.10.12>
       Use `lib.mkForce value` or `lib.mkDefault value` to change the priority on any of these definitions.»; }

This seems like a sane usage, so I'm expressing here that what dream2nix adds is just a default.

[yajo]

Oh, it seems I got confused and should have added python as the dependency, not python3: https://github.com/nix-community/dream2nix/blob/77eeb06927e94bc196444fcee2d08a20514443a3/modules/dream2nix/pip/default.nix#L9

Maybe this could be closed then.

[DavHau]

Hm, maybe we should refactor the whole thing to use python3, not python what do you think?

[yajo]

I think it's better to use python, not python3, because:

• You may want to build a python2 package.
• Some day, you may want to build a python4 package.

So, the fact you use python for the pip backend is better IMHO.

The fact you're using python3 for path module also makes sense, because it's the supported version: https://github.com/nix-community/dream2nix/blob/5a729cb75ae914b2e97114e1c0e9280953b7b488/modules/dream2nix/core/paths/find-root.py#L1

So, IMHO the better fix would be to package find-root.py separately, so you add that as a dependency, and not its python interpreter directly. Then we only have one python variable around, and it's the one for building python packages.

[DavHau]

@mergify rebase

[mergify[bot]]

rebase

❌ Pull request can't be updated with latest base branch changes

Mergify needs the author permission to update the base branch of the pull request. @moduon needs to authorize modification on its head branch.

[DavHau]

I can't rebase your PR's. Mind giving me permissions?

[yajo]

Sorry, I can't. Github doesn't allow that when the fork belongs to a team, like this one. Let me rebase it.

[phaer]

I think this is fixed?

On current main branch, python3 gets a mkOverride-priority of 1003, which is even a bit higher than mkDefault - so can be easily overridden with a simple setting (with or without mkDefault/mkForce)