this post was submitted on 17 Jan 2025
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PEP 735 does dependency group solve anything? (peps.python.org)
submitted 20 hours ago by [email protected] to c/[email protected]
23 comments fedilink hide all child comments
 

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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[–] [email protected] 1 points 20 hours ago (20 children)

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.

[–] eager_eagle 3 points 19 hours ago* (last edited 19 hours ago) (1 children)

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.

[–] [email protected] 1 points 18 hours ago (1 children)

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/

[–] eager_eagle 2 points 18 hours ago (3 children)

I didn't know about StrictYAML, we're really going in circles lol

TOML is already RW by Poetry, PDM, and uv.

[–] [email protected] 1 points 15 hours ago* (last edited 15 hours ago)

Not in circles, this is helping for me.

If you have strong support for a rw toml, would like to hear your arguments

[–] [email protected] 1 points 15 hours ago* (last edited 15 hours ago)

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

[–] [email protected] 1 points 15 hours ago* (last edited 15 hours ago) (2 children)

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

[–] FooBarrington 3 points 14 hours ago (2 children)

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".

[–] [email protected] 1 points 9 hours ago (1 children)

especially JS, some packages.json are super long. The sqlite author would blush looking at that

[–] FooBarrington 1 points 8 hours ago

Sure, but why is that a bad thing when you have lots of direct dependencies?

[–] [email protected] 1 points 9 hours ago (2 children)

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.

[–] eager_eagle 3 points 9 hours ago (2 children)

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.

[–] [email protected] 1 points 8 hours ago

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)

[–] [email protected] 1 points 8 hours ago (1 children)

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.

[–] FooBarrington 1 points 9 hours ago (1 children)

It's not schemaless at all, it's a dictionary of string to string. Not that complex.

[–] [email protected] 1 points 8 hours ago (1 children)

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.

[–] FooBarrington 1 points 8 hours ago

I'm not sure what you're talking about. My point was that dependency definitions in pyproject.toml aren't schemaless.

[–] eager_eagle 3 points 15 hours ago (1 children)

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.

[–] [email protected] 1 points 9 hours ago* (last edited 9 hours ago) (1 children)

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.

[–] eager_eagle 1 points 3 hours ago

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.

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