Uv's killer feature is making ad-hoc environments easy • Hacker News Board

Re: Uv's killer feature is making ad-hoc environments easy

#31

Post by eesmith » Sun, Jan 12, 2025, 9:07 PM UTC

faizshah wrote: post #16

I love this, the biggest problem I have right now with python scripts is distributing my single file utility scripts (random ops scripts). I wish there was a way to either shebang something like this or build a wheel that has the full venv inside.

https://peps.python.org/pep-0723/ is at the very least related. It's a way of specifying the metadata in the script, allowing other tools to do the right thing. One of the use cases is:

> A user facing CLI that is capable of executing scripts. If we take Hatch as an example, the interface would be simply hatch run /path/to/script.py [args] and Hatch will manage the environment for that script. Such tools could be used as shebang lines on non-Windows systems e.g. #!/usr/bin/env hatch run

https://micro.webology.dev/2024/08/21/uv-updates-and.html shows an example with uv:

> With this new feature, I can now instruct users to run uv run main.py without explaining what a venv or virtualenv is, plus a long list of requirements that need to be passed to pip install.

That ends:

> PEP 723 also opens the door to turning a one-file Python script into a runnable Docker image that doesn’t even need Python on the machine or opens the door for Beeware and Briefcase to build standalone apps.

Re: Uv's killer feature is making ad-hoc environments easy

#32

Post by PaulHoule » Sun, Jan 12, 2025, 9:08 PM UTC

poincaredisk wrote: post #14

nharada wrote: post #12

I really like uv, and it's the first package manager for a while where I haven't felt like it's a minor improvement on what I'm using but ultimately something better will come out a year or two later. I'd love if we standardized on it as a community as the de facto default, especially for new folks coming in. I personally now recommend it to nearly everyone, instead of the "welllll I use poetry but pyenv works or you…

I never used anything other than pip. I never felt the need to use anything other than pip (with virtualenv). Am I missing anything?

pip's resolving algorithm is not sound. If your Python projects are really simple it seems to work but as your projects get more complex the failure rate creeps up over time. You might

   pip install

something and have it fail and then go back to zero and restart and have it work but at some point that will fail. conda has a correct resolving algorithm but the packages are out of date and add about as many quality problems as they fix.

I worked at a place where the engineering manager was absolutely exasperated with the problems we were having with building and deploying AI/ML software in Python. I had figured out pretty much all the problems after about nine months and had developed a 'wheelhouse' procedure for building our system reliably, but it was too late.

Not long after I sketched out a system that was a lot like uv but it was written in Python and thus had problems with maintaining its own stable Python enivronment (e.g. poetry seems to trash itself every six months or so.)

Writing uv in Rust was genius because it eliminates that problem of the system having a stable surface to stand on instead of pipping itself into oblivion, never mind that it is much faster than my system would have been. (My system had the extra feature that it used http range requests to extract the metadata from wheel files before pypi started letting you download the metadata directly.)

I didn't go forward with developing it because I argued with a lot of people who, like you, thought it was "the perfect being the enemy of the good" when it was really "the incorrect being the enemy of the correct." I'd worked on plenty of projects where I was right about the technology and wrong about the politics and I am so happy that uv has saved the Python community from itself.

Re: Uv's killer feature is making ad-hoc environments easy

#33

Post by curiousgal » Sun, Jan 12, 2025, 9:08 PM UTC

uv has does not (nor do they plan to add) support for conda, and that is a deal-breaker.

Re: Uv's killer feature is making ad-hoc environments easy

#34

Post by eesmith » Sun, Jan 12, 2025, 9:10 PM UTC

easton wrote: post #20

faizshah wrote: post #16

I love this, the biggest problem I have right now with python scripts is distributing my single file utility scripts (random ops scripts). I wish there was a way to either shebang something like this or build a wheel that has the full venv inside.

There’s a shebang now. as of PEP 722 you can declare dependencies in a comment at the top of a single file script that a package manager can choose to read and resolve. uv has support for it: https://docs.astral.sh/uv/guides/scripts/#running-a-script-w... (which only helps if your team is all in on uv, but maybe they are)

PEP 722 was rejected. You are thinking of PEP 723, which was very similar to 722 in goals.

https://discuss.python.org/t/pep-722-723-decision/36763 contains the reasoning for accepting 723 and rejecting 722.

Re: Uv's killer feature is making ad-hoc environments easy

#35

Post by mdaniel » Sun, Jan 12, 2025, 9:11 PM UTC

stevage wrote: post #26

As a NodeJS developer it's still kind of shocking to me that Python still hasn't resolved this mess. Node isn't perfect, and dealing with different versions of Node is annoying, but at least there's none of this "worry about modifying global environment" stuff.

Caveat: I'm a node outsider, only forced to interact with it

But there are a shocking number of install instructions that offer $(npm i -g) and if one is using Homebrew or nvm or a similar "user writable" node distribution, it won't prompt for sudo password and will cheerfully mangle the "origin" node_modules

So, it's the same story as with python: yes, but only if the user is disciplined

Now ruby drives me fucking bananas because it doesn't seem to have either concept: virtualenvs nor ./ruby_modules

Re: Uv's killer feature is making ad-hoc environments easy

#36

Post by mikepurvis » Sun, Jan 12, 2025, 9:12 PM UTC

aidos wrote: post #28

mplewis wrote: post #19

Earlier quoted context omitted.

Pip only has requirements.txt and doesn't have lockfiles, so you can't guarantee that the bugs you're seeing on your system are the same as the bugs on your production system.

I’ve always worked around that by having a requirements.base.txt and a requirements.txt for the locked versions. Obviously pip doesn’t do that for you but it’s not hard to manage yourself. Having said that, I’m going to give uv a shot because I hear so many good things about it.

I’m grouchy because I finally got religion on poetry a few years ago, but the hype on uv is good enough that I’ll have to give it a shot.

Re: Uv's killer feature is making ad-hoc environments easy

#37

Post by throwup238 » Sun, Jan 12, 2025, 9:12 PM UTC

emiller88 wrote: post #29

There's so many more! 1. `uvx --from git+ https://github.com/httpie/cli httpie` 2. https://simonwillison.net/2024/Aug/21/usrbinenv-uv-run/ uv in a shebang

The uv shebang is definitely the killer feature for me, especially with so much of the AI ecosystem tied up in Python. Before, writing Python scripts was a lot more painful requiring either a global scripts venv and shell scripts to bootstrap them, or a venv per script.

I’m sure it was already possible with shebangs and venv before, but uv really brings the whole experience together for me so I can write python scripts as freely as bash ones.

Re: Uv's killer feature is making ad-hoc environments easy

#38

Post by miohtama » Sun, Jan 12, 2025, 9:14 PM UTC

easton wrote: post #20

faizshah wrote: post #16

I love this, the biggest problem I have right now with python scripts is distributing my single file utility scripts (random ops scripts). I wish there was a way to either shebang something like this or build a wheel that has the full venv inside.

There’s a shebang now. as of PEP 722 you can declare dependencies in a comment at the top of a single file script that a package manager can choose to read and resolve. uv has support for it: https://docs.astral.sh/uv/guides/scripts/#running-a-script-w... (which only helps if your team is all in on uv, but maybe they are)

Do other package managers support this yet?

Re: Uv's killer feature is making ad-hoc environments easy

#39

Post by airstrike » Sun, Jan 12, 2025, 9:17 PM UTC

astronautas wrote: post #17

astronautas wrote: post #13

Earlier quoted context omitted.

uh, thanks I guess.

How about "A UV feature that intrigues me most"?

Still clickbait if you don't say what the feature is.

Re: Uv's killer feature is making ad-hoc environments easy

#40

Post by whimsicalism » Sun, Jan 12, 2025, 9:18 PM UTC

poincaredisk wrote: post #14

nharada wrote: post #12

I really like uv, and it's the first package manager for a while where I haven't felt like it's a minor improvement on what I'm using but ultimately something better will come out a year or two later. I'd love if we standardized on it as a community as the de facto default, especially for new folks coming in. I personally now recommend it to nearly everyone, instead of the "welllll I use poetry but pyenv works or you…

I never used anything other than pip. I never felt the need to use anything other than pip (with virtualenv). Am I missing anything?

in my view, depending on your workflow you might have been missing out on pyenv in the past but not really if you feel comfortable self-managing your venvs.

now though, yes unequivocally you are missing out.