Support taplo configuration in pyproject.toml

[bollwyvl]

elevator pitch

Enable configuring taplo by looking for the well-known pyproject.toml file and reading [tool.taplo].

references

• Build wheels for Python package #549 (comment)

motivation

As a (mostly) python user, I've applied taplo (via the conda-forge redistribution of taplo-cli (disclaimer: maintainer) in a number of workflows, but have mostly relied on the CLI flags to avoid Yet Another Config File.

With the (hopefully) pending python distributions on #549, more python users will have access to an easy-to-manage version of taplo, which they could include in e.g. [project.optional-depenendencies.lint].

Many python-based tools have centralized on pyproject.toml's reserved, but unconstrained, [tool] section for their configuration. Adopting this convention would improve the overall experience for python projects that might only be using taplo for that file, making an additional top-level .taplo.toml a bit "noisier" than it needs to be.

alternatives

• augment the CLI to accept a different top-level table, e.g.

  taplo format --config pyproject.toml --config-table tool.taplo pyproject.toml

  • this... isn't terrible, and would avoid coupling too tightly to a specific ecosystem's conventions, which can always change

design ideas

• the docs might say something like

  By default, every tool looks for one in the working directory or the root of the workspace by the following names (in precedence order):

  • .taplo.toml
  • taplo.toml
  • pyproject.toml under the [tool.taplo] table

• a minimal viable pyproject.toml is pretty much what one would expect:

  [build-system]
  build-backend = "flit_core.buildapi"
  requires = ["flit_core >=3.7.1,<4"]
  
  [project]
  name = "some-neat-project"
  readme = "README.md"
  classifiers = ["License :: OSI Approved :: MIT License"]
  requires-python = ">=3.9"
  dynamic = ["version", "description"]
  
  [project.optional-dependencies]
  lint = ["taplo", "ruff"]
  
  [tool.ruff]
  # ... oh boy it's a lot
  
  [tool.taplo]
  include = ["pyproject.toml"]
  
  [[tool.taplo.rule]]
  include = ["pyproject.toml"]
  keys = ["dependencies", "*-dependencies"]
  
  [tool.taplo.rule.formatting]
  reorder_keys = true

• getting this into the usual suspects (e.g. schemastore.org) would make it pretty much Just Work for a lot of language server users:

  "properties": {
      "tool": {
        "title": "Tool-specific configuration",
        "type": "object",
        "description": "A table for tool configurations.\n\nEvery tool that is used by the project can have its own sub-table for its configuration.\n",
        "additionalProperties": {
          "type": "object"
        },
        "x-taplo": {
          "links": {
            "key": "https://www.python.org/dev/peps/pep-0518/#id28"
          }
        },
        "properties": {
          "taplo": {
            "$ref": "https://json.schemastore.org/taplo.json"
          },

And thanks for taplo 🤗 !