So You Want to Solve Python Packaging: A Practical Guide
First, the technical: Python is used by vastly different groups of people, some that don't identify as "developers". Those groups often have disparate expectations about how packaging should work. Some don't even know what a package is.
Some don't even know they're using Python! Here's some examples: Python's in the Linux Standard Base and bunch of critical Linux stuff is written in Python. Distros gotta package those & their deps into their package database (deb/rpm).
Most distros want nothing to do with the language-specific package manager. They want to manage everything though rpm/deb/portage/whatever and they don't want you fucking around with system packages. Ever got burned by Python included with macOS? Yeah, same deal
So OS vendors want Python to be invisible to the user. They want it for system purposes, and they want to distribute python apps, scripts, and packages on their own terms. Cool. Let's pick another group: academics and researchers.
They want to do their research. They don't want to program Python. They want to work their data, create visualizations, and very importantly: they want fellow researchers to be able to use their code. These folks don't really want to think about packaging.
That's because web devs have different expectations. They *expect* to work with a packaging tool. They expect to find and install dependencies. They don't expect to work with a ton of native dependencies. They don't have the same problems.
This only scratches the surface of the technical complexity here. The reason there are so many tools for managing Python dependencies is because Python is not a monoculture and different folks need different things.
> my experience is that it gets weird-and-broken pretty quick in ways that are confusing,
This usually happens somewhere in the vicinity of loading drivers (e.g. libcuda or libGL), which currently is only accommodated by wrappers (nixglhost, nixGL) and, yes, sucks. It's hard to improve upon because of how other dsitributions mix userspace drivers and normal libraries, but there are some cursed ideas being talked about involving libcapsule...
@nobody @whack @stargirl It's a fair critique, though, and one that spawns from the *same* memetic issue as in Python packaging, so it's worth examining.
Sure, a Nix package *should* only rely on being located in /nix/store next to its dependencies. But as you've listed, there's piles of ambient authorities and mutable state which also must be correctly configured in order for some packages to run.
This is *exactly* analogous to Python packages which aren't pure statically-imported Python modules. In a simpler world, we would deploy Python apps by tossing all Python modules into a single ZIP file, but because CPython allows extension modules and exposes a C API, a practical Python app must also depend on C runtime and C linkage.
This isn't hypothetical. RPython, the toolkit for building PyPy, is pure Python 2.7. My rpypkgs flake https://github.com/rpypkgs/rpypkgs "installs" RPython packages by unpacking all of them to a common build directory.
Stargirl
Corbin
Jordan Sissel
Else, Someone