In a requirements-*.in file, at the top of the file, are lines with -c and -r flags followed by a requirements-*.in file. Uses relative paths (ignoring URLs).
Say have docs/requirements-pip-tools.in
-r ../requirements/requirements-prod.in
-c ../requirements/requirements-pins-base.in
-c ../requirements/requirements-pins-cffi.in
...
The intent is compiling this would produce docs/requirements-pip-tool.txt
But there is confusion as to which flag to use. It’s non-obvious.
constraint
Subset of requirements features. Intended to restrict package versions. Does not necessarily (might not) install the package!
Does not support:
-
editable mode (-e)
-
extras (e.g. coverage[toml])
Personal preference
-
always organize requirements files in folder(s)
-
don’t prefix requirements files with
requirements-, just doing it here -
DRY principle applies; split out constraints which are shared.
Constraints are useful for restricting build dependencies of your dependencies, especially if they follow PEP-518.
Was working under the assumption that everyone considered constraints (-c) to be non-negotiable required feature.
If only have requirements (-r), in a centralized pyproject.toml, then how to tackle multiple specific dependency hell issues without causing a huge amount of interconnected clutter?
Why do you need to have a centralized pyproject.toml?
Within the context of resolving dependency conflicts, poetry decided pyproject.toml is a great place to put requirements.
This is what people know.
pyproject.toml or venv management should otherwise never come into the conversation.
My personal opinion is: venv, pip, pyenv, pip-tools, and tox are sufficient to manage venvs.
venvs are not required to manage requirement files. It’s a convenience so dev tools are accessible.
Currently the options are: poetry or uv.
With honorable mention to pip-compile-multi, which locks dependencies.
poetry and uv manage venvs… Why?
I was asking why you need to have a centralized pyproject.toml file, which is apparently why you need constraint files? Most people don’t have this workflow, so are not even aware of constraint files, much less see them as a must-have.
I totally agree with you. So not the best champion of the poetry approach. Someone else would need to step forward, even as devils advocate, and champion poetry. Even if tongue in cheek. Anyone?
Normally, there is no connection between constraint files and pyproject.toml
Python appears to be forever stuck with plain text requirement|constraint files. So putting them into pyproject.toml is just adding an extra layer of complexity.
If most people prefer pyproject.toml over requirements.txt, even if it does not support everything you need, isn’t it more likely that you will have to change workflow rather than python remaining stuck with requirement.txt?
are you really asking why use 1 tool instead of 5?
venvs and dependency management are such interconnected concepts, I don’t even know how you could sustainably handle them separately.
UNIX philosophy. One tool that does one thing well
Best to have a damn good reason when breaking this principle (e.g. vendoring) or be funded by Money McBags
requirements files are requirements files, not venvs. They may install into venv, but they are not venvs themselves. The only thing a venv provides that is of interest to ur requirements files are: the relative folder path (e.g. ‘.venv’) and python interpreter path. Nothing more. When using tox, the py version is hardcoded, so only need to provide the relative folder path.
The venv management tools we have are sufficient. the problem is not the venv, it’s managing the requirements files.
Your 1 tool suacks just as much as my 5 tools when it comes to managing requirement files. None of them do the job.
The Python env has been trying this multiple tools approach for decades and consistently delivering a worse experience than languages that pack most things in one tool.
Rust is a bliss to use, largely thanks to cargo that takes care of build, dependencies, locking, tests, publishing etc. You say do one thing and do it well. In my experience they often do one thing in a mediocre way, while forcing users to understand which and how to combine dozens of possible tools in a development environment that keeps changing. It’s messy, slow, error prone, and requires constant developer attention.
Most languages don’t support packages containing multiple languages (C/C++, Cython, and Python). So Python situation is much more complex.
distutils
setuptools is complex
pip is complex
requirements files are complex
space aliens wrote pytest (and pluggy)
publishing and dependencies are super centralized, depending on pypi.org way too much.
Comparing Rust vs Python is nonsense. Rust is a stricter compiler on top of C. It has to deal with legacy C libraries. It has it very very easy.
and despite those differences, uv is essentially cargo for Python, showing it is possible.