How might uv use hatchling? Where is it?

[pycaw]

I can't find it anywhere, yet uv uses it without issue to produce builds. Not in my venv, not there as a uv tool/pipx package or a system package. I want to write a custom hook to embed git version. I feel like an idiot...

This is how it's described in my pyproject.toml:

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

I'd want to use the same hatchling package that's used by uv, wherever it's stored/cached. Or maybe if I specify it a dep (part of group dependency "dev" maybe) then uv build would pick that up as well?

[ofek]

Does this help? https://hatch.pypa.io/latest/how-to/plugins/testing-builds/

[pycaw]

I'm afraid not really. And this doc made me think I don't need a package for the (custom hook) plugin but simply a hatch_build.py which will be picked up by hatch.

[ofek]

If you don't plan on distributing it but rather use for a single project then yes that's all you need!

[pycaw]

I found it:
~/.cache/uv/builds-v0/.tmpkMKgQV/lib/python3.10/site-packages/hatchling

I corrected my pyproject:

[tool.hatch.build.targets.sdist.hooks.custom]
path = "scripts/hatch_build.py"

Situation now:

1. Ignore the lack of linting while developing my custom hook
2. Add hatch+hatchling to my venv

• uv doesn't pick this up, so know I have potentially different versions used (execution, linting)
• This also brings in a TON of dependencies (including uv :D), wow I didn't imagine that. Hatchling is much more lightweight of course, if uv doesn't pick up even if hatch is installed then this can suffice anyways.

This is now more of a uv issue I suppose, and I think I will be okay with option 1. Or mixing the two....

[ofek]

• I don't understand what you're talking about linting, can you please explain?
• You don't need Hatch.
• You don't need to manually install Hatchling as the plugin logic will happen whenever a build occurs.

[pycaw]

I have a build_hatch.py sitting in my project with no linting so I wanted to do something, manually. Yet, hatchling is used by uv, I wanted to use the same one to be sourced by the interpreter for the linting. Not really feasible so I have a seperate hatchling installed in my local venv. Now linting works. I will probably get rid of it as I am happy with my hook and won't touch it.

It's confusing to me where the boundary between hatch and hatchling lies. I. e., [tool.hatch.*], why not [tool.hatchling.*]?. Makes one think hatch is used. Their docs are also kind of merged.

[ofek]

• The docs are a bit merged but I think it's an organizational issue. Please let me know how I might better document writing plugins.
• Hatchling will be used and maintained in its own build environment by tools like Hatch and UV, you don't need to know anything about it. All you require is that plugin file.

[pycaw]

I just started using your handy hatch-vcs package and so I will be using hatch as well (as a uv tool) to do things like sync the version file instead of building sometimes or to print the current version. So I will use hatch too. I can't do either of these with uv.

I will also need to manage hatchling myself when I want linting for hooks.

Regarding docs. Please excuse my directness, but to me, this page is a mess: https://hatch.pypa.io/latest/config/build/. This is the "hatchling docs", if you can manage to navigate here from the homepage of hatch (where the "hatchling docs" google search will send you). Where additionally you need to go to Configuration on the top bar and then Build (and not initially Builds or Introduction). hatchling is supposed to be totally decoupled from hatch, yet you have to go though hatch's docs and even once you get to the page that describes options that are processed by hatchling, every line there wants to tell you otherwise. This page is where the ubiquitous,

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

description resides. Options then above and below this seem as if they were meant for hatch. But no, they are meant for the build system, hatchling.