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What is Tach?

Tach allows you to control dependencies between your Python modules. Modules can also define an explicit public interface to prevent deep coupling.

This creates a modular architecture, which makes development easier.

If a module tries to import from another module that is not listed as a dependency, Tach will report an error.

When a module has a public interface, any import which does not go through the public interface will cause Tach to report an error.

Dependencies can be additionally marked as ‘deprecated’. Tach will not report an error but will surface usages of the deprecated dependency.

Tach is a CLI tool, and is ideal for pre-commit hooks and CI checks.

Tach is:

  • 🌎 Open source
  • 🐍 Installable via pip
  • 🔧 Able to be adopted incrementally
  • ⚡ Implemented with no runtime impact
  • ♾️ Interoperable with your existing systems (cli, hooks, ci, etc.)

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Commands

  • tach mod - Interactively define module boundaries.
  • tach check - Check that boundaries and interfaces are respected.
  • tach sync - Sync constraints with the actual dependencies in your project.
  • tach show - Visualize your project’s dependency graph.
  • tach report - Generate a dependency report for a file or module.
  • tach test - Run only the tests impacted by your changes
  • tach install - Install Tach into your development workflow (e.g. pre-commit)
Why Tach