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astral-sh / uv

An extremely fast Python package and project manager, written in Rust.
https://docs.astral.sh/uv
Apache License 2.0
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Add --resolution=local or similar to help projects supporting wide ranges of Python versions #7889

Open TormodLandet opened 1 month ago

TormodLandet commented 1 month ago

I have several projects that supports a large range of versions of Python and numpy, starting from (Python=3.7, numpy=1.0) and up to (Python=3.12, numpy=2.1). I would like to test these projects at both ends of the supported version spectrum, and I would like to use uv for that.

If my project was small enough to fit inside a single script, I could use inline script metadata and the project could be run with both --python=3.12 and --python=3.7 arguments to uv run myscript.py. The resolution used by uv is somehow "local" in this case and uv will select different supported versions of numpy depending on the version of Python supplied to uv run.

# /// script
# python-version = ">=3.7"
# dependencies = [
#   "numpy",
# ]
# ///

import numpy as np
import sys

print(sys.version)
print(np.version.version)

However, if the same is defined in the pyproject.toml file then uv run will try to make a universal resolution which fails since numpy version 2.1 is available for Python 3.12 and not for Python 3.7 and vice versa with numpy version 1.25.

To test my project I must add two extra steps:

1) Test on oldest version of Python with uv run --python=3.7 ... (run pytest or manual tests etc) 2) Modify pyproject.toml and set requires-python = ">=3.12" 1) Test on newest version of Python with uv run --python=3.12 ... 2) Modify pyproject.toml and set requires-python back to ">=3.7"

It would be great if projects that support a wide range of Python versions (so wide that universal resolution is not possible) could still use uv to test for both the oldest and newest version of Python. Right now I must modify pyproject.toml which feels like a hack and if I forget to reset requires-python back to ">=3.7" then I guess my wheel files will refuse to install on older versions of Python? (universal wheels, should support "all" versions of Python 3 on all platforms).

I may have missed how to turn of universal resolution in the docs, in that case sorry! It would be nice if uv sync also supported something like --python=3.12 --resolution=local to resolve only for the current version of Python on the current platform.

Thank you so much for uv, by the way. So much faster than conda for me.

konstin commented 1 month ago

For your case, you can get different numpy versions on different Python versions by using forking on markers (see https://docs.astral.sh/uv/reference/resolver-internals/#forking). Effectively, you declare slices of Python version ranges and the numpy range you want for those Python versions, something like:


dependencies = [
    "numpy; python_version >= '3.12'",
    "numpy>=2; python_version >= '3.9' and python_version < '3.12'",
    "numpy<2; python_version < '3.9'",
    # ...
]