A module can be marked ‘unchecked’ by setting unchecked: true in its configuration within tach.toml.

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How does it work?

An unchecked module should be thought of as a ‘known’ module which does not have any restriction on its dependencies.

The purpose of configuring an unchecked module is to better support incremental adoption of Tach.

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Example

Suppose you are adding Tach to an existing project, and you want to start by restricting dependencies for only one part of the codebase.

my_repo/
  tach.toml
  utils.py
  filesytem/
    service.py
  parsing/
    service.py
  core/
    module1.py
    module2/
      __init__.py
      service.py
    module3.py
  docs/
  tests/

Given the example project above, one might mark utils, filesystem, parsing, and core.module(1,2,3) as modules.

After doing this, tach sync would detect and add all the dependencies found between these modules, and tach check would enforce them.

However, suppose that parsing, core.module2, and core.module3 are changing rapidly, and errors from tach check due to changing dependencies are unnecessary. By default, Tach would require the configuration to be ‘all-or-nothing’ - these errors would be unavoidable if these modules are themselves dependencies of more stable modules.

[[modules]]
path = "utils"
utility = true
depends_on = []

[[modules]]
path = "filesystem"
depends_on = []

[[modules]]
# this module is not checked because its errors would be noisy
path = "parsing"
unchecked = true
depends_on = []

[[modules]]
# Tach will verify this module's dependencies,
# even though they are unchecked
path = "core.module1"
depends_on = ["core.module2", "core.module3", "parsing"]

[[modules]]
# this module is not checked because its errors would be noisy
path = "core.module2"
unchecked = true
depends_on = []

[[modules]]
# this module is not checked because its errors would be noisy
path = "core.module3"
unchecked = true
depends_on = []

Using unchecked: true in the configuration above allows restricting dependencies for core.module1 at a fine-grained level without needing to restrict dependencies for all other modules.

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