#til #python #uv

(via epistasis on HN)

Semantic versioning is difficult. Not everyone has the same idea of what “breaking change” means, and depending on your language and tooling “breaking” changes can sneak in despite your best efforts.

One possible mitigation is to record when you resolved your dependencies and ignore anything published after that date. It's crude, and relies on package dependencies not monkeying with stuff that's already been published, but it's easy to understand and you can do it with uv.

It's documented here.

Put a date in your pyproject.toml file and subsequent invocations of uv will ignore anything published after the cutoff:

[tool.uv]
exclude-newer = "2023-10-16T00:00:00Z"

You can also use it in the “inline metadata” format for scripting! From the uv docs:

# /// script
# dependencies = [
#   "requests",
# ]
# [tool.uv]
# exclude-newer = "2023-10-16T00:00:00Z"
# ///

import requests

print(requests.__version__)

This use case seems particularly valuable: if I write a quick script I probably care more about it not breaking than I care about it getting updated dependencies. It's nice that uv offers a way to keep code running rather than forcing me to update it or throw it out.