Ruff config & pre-commit hook

[Ruff](https://docs.astral.sh/ruff/):
An extremely fast Python linter and code formatter, written in Rust.

Replaces existing Black hook. Runs on pre-commit (contributors should
run `pre-commit install` in the repo root to set this up.)

.hooks/kx-ruff.py

@@ -0,0 +1,17 @@
+#!/usr/bin/env python3
+import subprocess
+import sys
+
+filez = sys.argv[1:]
+
+print("Running ruff linter")
+# TODO: should we enable `--unsafe-fixes` here?
+# (Most of the 'unsafe' fixes appear to be "it might move a comment slightly" level of unsafe)
+subprocess.check_call(["ruff", "check", "--fix", *filez])
+
+print("Running ruff formatter")
+subprocess.check_call(["ruff", "format", *filez])
+
+# pre-commit doesn't add changed files to the index. Normally changed files fail the hook.
+# however, just calling git add sneakily works around that.
+subprocess.check_call(["git", "add"] + filez)

.pre-commit-config.yaml

@@ -10,10 +10,13 @@ repos:
       - id: check-yaml
       - id: check-added-large-files
       - id: check-json
-  - repo: https://github.com/psf/black
-    rev: 22.3.0
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    # Ruff version.
+    rev: v0.6.1
     hooks:
-      - id: black
+      - id: ruff
+        # Run both the linter and formatter (and commit the changes automatically)
+        entry: ".hooks/kx-ruff.py"
   - repo: https://github.com/sirosen/check-jsonschema
     rev: 0.6.0
     hooks:

pyproject.toml

@@ -1,5 +1,21 @@
-[tool.black]
-target-version = ['py37']
-
 [tool.pyright]
 exclude = ["**/__pycache__", "**/build", "venv"]
+
+
+[tool.ruff]
+line-length = 88
+target-version = "py310"
+force-exclude = true
+
+[tool.ruff.lint]
+preview = true
+select = [
+  "F402",
+  "F404",
+  "F823",
+  "F821",
+  "F822",
+  "E112",
+  "E113",
+  "E902",
+]