Dogmatic

An opinionated Python linter and formatter built on Ruff, with native rules for typed data boundaries, explicit dependency injection, async execution, pytest, named constants, and focused application modules.

uv tool install dogmatic
dogmatic check .
dogmatic format .

The Python package also supports python -m dogmatic. Dogmatic uses Ruff's configuration format, including [tool.ruff] in pyproject.toml, ruff.toml, and existing rule selectors and suppressions.

Dogmatic's release version is independent of its Ruff engine version. Ruff's required-version setting checks the engine version, currently 0.16.6.

All custom checks and companion application policies are enabled by default. No policy download or enablement flags are required. The executable includes offline explanations, configuration examples, and the complete default policy:

dogmatic guide
dogmatic guide --starter
dogmatic guide --policy
dogmatic rule custom-repository-boundary
dogmatic config lint.custom

Most rules work immediately. Repository boundaries require module mappings; application-specific validators, clients, and setup functions can be registered with lint.custom. Merge the starter configuration into your existing pyproject.toml and replace its example package names.

Application modules exceeding 300 code lines are flagged for review and splitting into focused submodules. Comments and docstrings do not count; tests, stubs, and notebooks are exempt. Configure lint.custom.max-module-lines to change the limit.

dogmatic check . also flags repeated consecutive statement blocks within and across application modules, starting at five statements. This includes executable module code, main guards, class bodies, functions, and nested control flow; declarations alone do not qualify. Configure lint.custom.min-duplicate-statements to adjust this threshold. Comments, docstrings, spacing, and consistent local-variable renames are ignored. External APIs, literal values, and variable-use relationships must match. Cross-module detection requires a CLI file collection and does not run on stdin or in the language server.

Three additional default rules suggest shared abstractions when code differs: custom-duplicate-algorithm recognizes consistent policy-constant substitutions, custom-duplicate-workflow allows a small number of inserted steps, and custom-duplicate-computation compares sums and collection-building loops with comprehensions. Their offline explainers describe thresholds and exclusions. These are heuristic findings for review, with no automatic fixes; each rule can be disabled independently through the usual selectors.

Project settings and CLI flags override defaults. Use lint.ignore for targeted exceptions; lint.select replaces the selection. --isolated keeps Dogmatic's defaults while ignoring configuration files. --no-preview disables the default preview custom rules. Formatter preview is unchanged.

Dogmatic includes Ruff, originally developed by Astral Software Inc., under the MIT license. The upstream project is available at astral-sh/ruff. Dogmatic is an independent distribution; its application-specific policies are not upstream Ruff rules.