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Uv: Running a script with dependencies

docs.astral.sh

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Re: Uv: Running a script with dependencies

#2

Post by gopalv »

This is my absolute favourite uv features and the reason I switched to uv.

I have a bunch of scripts in my git-hooks which have dependencies which I don't want in my main venv.

#!/usr/bin/env -S uv run --script --python 3.13

This single feature meant that I could use the dependencies without making its own venv, but just include "brew install uv" as instructions to the devs.

Re: Uv: Running a script with dependencies

#3

Post by Bluestein »

gopalv wrote: post #2

This is my absolute favourite uv features and the reason I switched to uv. I have a bunch of scripts in my git-hooks which have dependencies which I don't want in my main venv. #!/usr/bin/env -S uv run --script --python 3.13 This single feature meant that I could use the dependencies without making its own venv, but just include "brew install uv" as instructions to the devs.

I honestly believe this is a killer (killer) feature.-

Re: Uv: Running a script with dependencies

#4

Post by simonw »

The "declaring script dependencies" thing is incredibly useful: https://docs.astral.sh/uv/guides/scripts/#declaring-script-d...

  # /// script
  # dependencies = [
  #   "requests
Save that as script.py and you can use "uv run script.py" to run it with the specified dependencies, magically installed into a temporary virtual environment without you having to think about them at all.

It's an implementation of Python PEP 723: https://peps.python.org/pep-0723/

Claude 4 actually knows about this trick, which means you can ask it to write you a Python script "with inline script dependencies" and it will do the right thing, e.g. https://claude.ai/share/1217b467-d273-40d0-9699-f6a38113f045 - the prompt there was:

  Write a Python script with inline script
  dependencies that uses httpx and click to
  download a large file and show a progress bar
Prior to Claude 4 I had a custom Claude project that included special instructions on how to do this, but that's not necessary any more: https://simonwillison.net/2024/Dec/19/one-shot-python-tools/

Re: Uv: Running a script with dependencies

#5

Post by minimaxir »

simonw wrote: post #4

The "declaring script dependencies" thing is incredibly useful: https://docs.astral.sh/uv/guides/scripts/#declaring-script-d... # /// script # dependencies = [ # "requests Save that as script.py and you can use "uv run script.py" to run it with the specified dependencies, magically installed into a temporary virtual environment without you having to think about them at all. It's an implementation of Python PEP 723: h…

I thought that was a heart emoticon next to requests, for a second.

Re: Uv: Running a script with dependencies

#6

Post by dwood_dev »

gopalv wrote: post #2

This is my absolute favourite uv features and the reason I switched to uv. I have a bunch of scripts in my git-hooks which have dependencies which I don't want in my main venv. #!/usr/bin/env -S uv run --script --python 3.13 This single feature meant that I could use the dependencies without making its own venv, but just include "brew install uv" as instructions to the devs.

Completely agree. UV for stalled what was going to be a major project to move lots of python to golang. There will still be a lot migrated, but smaller script like things are no longer in scope.

Re: Uv: Running a script with dependencies

#8

Post by simonw »

satertek wrote: post #7

Why doesn't pip support PEP 723? I'm all for spreading the love of our lord and savior uv, but it should be necessary to have an official implementation.

I don't know if there's an official reason, but my guess is that it's slightly out of scope for pip: pip is a packaging installation tool, not a virtual environment managing system.

uv, being both, is a more natural fit for an implementation of that PEP.

Here's a relevant discussion: https://discuss.python.org/t/idea-introduce-standardize-proj...

Re: Uv: Running a script with dependencies

#10

Post by m4r71n »

Oh nice, I was already a happy user of the uv-specific shebang with in-script dependencies, but the `uv lock --script example.py` command to create a lock file that is specific to one script takes it to another level! Amazing how this feels so natural and yet only appeared after 20+ years of Python packaging.
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