PEP 735 what is it’s goal? Does it solve our dependency hell issue?
A deep dive and out comes this limitation
The mutual compatibility of Dependency Groups is not guaranteed.
– https://peps.python.org/pep-0735/#lockfile-generation
Huh?! Why not?
mutual compatibility or go pound sand!
pip install -r requirements/dev.lock
pip install -r requirements/kit.lock -r requirements/manage.lock
The above code, purposefully, does not afford pip a fighting chance. If there are incompatibilities, it’ll come out when trying randomized combinations.
Without a means to test for and guarantee mutual compatibility, end users will always find themselves in dependency hell.
Any combination of requirement files (or dependency groups), intended for the same venv, MUST always work!
What if this is scaled further, instead of one package, a chain of packages?!
I think you’re expecting this PEP to be something that it is not. It is not supposed to be a full solution to dependency hell (which I’m not really sure that there is). It is supposed to just allow a static method to declare dependencies, notably supporting both Python package and non-Python-package dependencies. There are plenty of use cases for when you might want incompatible sets of dependencies, for a simple example consider a graphics library with both a Vulkan and OpenGL backend. You could reasonably argue that you should allow both to coexist and just select the best one at runtime, but when you’re dealing with native libraries that’s not always possible, and there is no way to make a guarantee about compatibility without excluding all non-pure Python dependencies.
Wasn’t aware that this PEP is including non-Python package dependencies or how that affects dependency resolution.
Managing python dependencies is challenging enough
Limitations of requirements.txt files
– https://peps.python.org/pep-0735/#limitations-of-requirements-txt-files
The only benefit i can see, is to attempt to bring requirements files into
pyproject.tomland an additional layer to abstract away from pip.^^ this does not keep me awake at night nor is it a substitute for porn
The PEP author’s intentions are good, puts focus on a little discussed topic.
The outcome … questionable
If this is all it’s doing, that’s not enough. Ignores the elephant in the room.
Which are
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fixing dependency conflicts
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mutual compatibility
Fixing dependency conflicts would be easier if can work with existing proven tooling. Which acts upon r/w files rather than pyproject.toml, a config file; shouldn’t constantly be updated.
additional layer to abstract away from pip
reqs.txt files are not standardized and pip can read from a
pyproject.toml- which is - usingpip install .there are still many unresolved matters with dependency resolution, but we need to leave
requirements.txtfiles behind.Throwing out an alternative. Not making the assumption that more TOML is better. Cuz the contents of those
requirements.txtfiles are rw, not ro. I seepyproject.tomlas a ro configuration file.Do you agree or should
pyproject.tomlbe rw?Another option, strictly validated YAML.
For the configuration section, before parsing occurs, strict validation occurs against a schema.
TOML vs strictyaml – https://hitchdev.com/strictyaml/why-not/toml/
I didn’t know about StrictYAML, we’re really going in circles lol
TOML is already RW by Poetry, PDM, and uv.
Not in circles, this is helping for me.
If you have strong support for a rw toml, would like to hear your arguments
Yeah, but should it be (rw)?
If it’s rw, it’s a database, not a config file.
No software designer thinks … postgreSQL, sqlite, mariadb, duckdb, … nah TOML
Or at least yaml turns out to be not a strange suggestion
it’s a config file that should be readable and writeable by both humans and tools. So yeah, it makes sense.
And I don’t lile yaml personally, so that’s a plus to me. My pet peeve is never knowing what names before a colon are part of the schema and which ones are user-defined. Even with strictyaml, reading the nesting only through indentation is harder than in toml.
You are not wrong, yaml can be confusing.
Recently got tripped up on sequence of mapping of mapping. Which is just a simple list of records.
But for the life of me, couldn’t get a simple example working.
Ended up reversed the logic.
Instead of parsing a yaml str. Created the sample list of dict and asked strictyaml to produce the yaml str.
Turns out the record is indented four spaces, not two.
- file: "great_file_name_0.yml" key_0: "value 0" - file: "great_file_name_1.yml" key_0: "value 0"Something like ^^. That is a yaml database. It has records, a schema, and can be safely validated!
The strictyaml documentation covers ridiculously simple cases. There are no practical examples. So it was no help.
Parser kept complaining about duplicate keys.
It has records, a schema, and can be safely validated!
uh… a database implies use of a database management system. I don’t think saying that a YAML/TOML/JSON/whatever file is a database is very useful, as these files are usually created and modified without any guarantees.
It’s not even about being incorrect, it’s just not that useful.
You have a strange definition of “database”. Almost every language I touch on a daily basis (JS, Rust, C#) uses their package meta file to declare dependencies as well, yet none of those languages treat it as a “database”.
especially JS, some packages.json are super long. The sqlite author would blush looking at that
Sure, but why is that a bad thing when you have lots of direct dependencies?
In this super specific case, the data that is being worked with is a many list of dict. A schema-less table. There would be frequent updates to this data. As package versions are upgraded, fixes are made, and security patches are added.
It’s not schemaless at all, it’s a dictionary of string to string. Not that complex.
It seems you’re describing a lock file. No one is proposing to use or currently using pyproject.toml as a lock file. And even lock files have well defined schemas, not just an arbitrary JSON-like object.
Highly suggest reading the strictyaml docs
The author lays out both
Should be required reading for anyone dealing with config files, especially those encountering yaml.
Warning: After reading these, and confirming the examples yourself, seeing packages using pyyaml will come off as lessor
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setuptools maintainers discuss pyproject.toml validation.
"I was under the impression that PyPI implements validation of the distribution files metadata, but if it does, the validation is not very strict. What is validated strictly is the form data that is sent alongside the distribution files. That can be tweaked as needed to support the metadata emitted by existing setuptools releases.
pip is most likely the most permissive consumer of metadata, thus I don’t expect it to do any validation."
https://github.com/pypa/setuptools/issues/4759#issuecomment-2503640532
Here is the spaghetti code doing the validation as of
setuptools-75.8.0Found this out when investigating pep639 support issues. Long story short not yet fully implemented.
