Python @programming.dev logging_strict @programming.dev 2 days ago

PEP 735 does dependency group solve anything?

peps.python.org PEP 735 – Dependency Groups in pyproject.toml | peps.python.org

This PEP specifies a mechanism for storing package requirements in pyproject.toml files such that they are not included in any built distribution of the project.

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?!

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26 comments

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.toml and 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

fixing dependency conflicts

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 - using pip install .
  
  there are still many unresolved matters with dependency resolution, but we need to leave requirements.txt files behind.
  
  Throwing out an alternative. Not making the assumption that more TOML is better. Cuz the contents of those requirements.txt files are rw, not ro. I see pyproject.toml as a ro configuration file.
  
  Do you agree or should pyproject.toml be 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
  
  Highly suggest reading the strictyaml docs
  
  The author lays out both
  
  Why
  
  Why not
  
  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
  
  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
  
  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 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.
  
  parsing lock files
  
  There's a few edge cases on parsing dependency urls. So it's not completely black and white.
  
  just have to read over to pip-compile-multi to see that. (i have high praise for that project don't get me wrong)
  
  then i'm misunderstanding what data dependencies groups are supposed to be storing. Just the equivalent of requirements.in files and mapping that to a target? And no -c (constraints) support?!
  
  Feels like tying one of hands behind our back.
  
  see https://packaging.python.org/en/latest/specifications/dependency-groups/#dependency-groups
  
  It's not schemaless at all, it's a dictionary of string to string. Not that complex.
  
  The strictyaml schema holds a pinch of nuance.
  
  The value argument is automagically coersed to a str. Which is nice; since the field value can be either integer or str. And i want a str, not an int.
  
  A Rust solution would be superior, but the Python API is reasonable; not bad at all.
  
  I'm not sure what you're talking about. My point was that dependency definitions in pyproject.toml aren't schemaless.
  
  strict schema and a spec are not the same. package pyproject-validate can check if a pyproject.toml follows the spec, but not be using a strict schema.
  
  A schema is similar to using Rust. Every element is strictly typed. Is that an int or a str is not enforced by a spec
  
  If there was a strict schema, package pyproject-validate would be unnecessary
  
  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.
  
  But it's treated 100% like a crappy CRUD database with no modern features or SQL
  
  it's a file containing records with a strict schema. And nothing else

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