Why is Python specified as a dependency?

[janjagusch]

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the documentation and believe that my question is not covered.

Issue

I was wondering why poetry specifies the compatible Python version in the tool.poetry.dependencies section, together with actual Python package dependencies. Is there any fundamental reason for that?

I am asking because this can cause issues for automatic dependency updating tools like renovate, where this currently triggers the following warning:

Failed to look up dependency python

Of course this can easily be fixed downstream. It just made me wonder why this is the desired behavior.

---

Example of a pyproject.toml file created with poetry init:

[tool.poetry]
name = "my-project"
version = "0.1.0"
description = ""

[tool.poetry.dependencies]
python = "^3.7"

[tool.poetry.dev-dependencies]

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"

[abn]

@janjagusch this is as per current design. Python is in-effect a dependency of the project. From this perspective, it makes sense where it is at. Any parsers of the poetry config section should treat python as a reserved key. Do you think one of the other sections make better sense?

[hobofan]

Coming from other languages I would rather expect it to be a key of the tool.poetry section, and seeing it as a dependency was definitely confusing at first. I think a key under build-system might also be understandable, though I guess that section is standardized via a PEP.

A short survey of other language package managers:

• Cargo (Rust), has the key edition (and will likely get a key like rust) in the package section, which is equivalent to tool.poetry

• In Ruby, you have both a .gemspec file with a spec.required_ruby_version, and the ruby directive in a Gemfile

• In NPM (Node.js), you have the engines.node key

• In Composer (PHP), you have a config.platform key

• In Haskell, Cabal doesn't seem to have an option to specify a Haskell version, while stack has a top-level compiler key