No Touching!

A mix task to let you know if you're using private modules or functions.

Run the task with mix private.check.

If you are calling a private function in a different application (as defined by the top level module for that application), then the mix task will fail.

A top level module is something like MyApp or Ecto or Enum. Any modules within that namespace are allowed to call any private functions in any other modules in that namespace.

For example, MyApp.Users can call private functions on MyApp.Repo because they have the same top level module - MyApp. But MyAppWeb.UserController cannot call any private functions on MyApp.Users because they have different top level modules MyAppWeb vs MyApp.

A function is private if:

1. The function has @doc false
2. The function is in a module with @moduledoc false
3. The function or module is annotated with @doc private: true

If you want to make a single function in a private module be public, you can add @doc private: false to that function.

This runs recursively in umbrella projects.

Installation

Add no_touching to your list of dependencies in mix.exs:

def deps do
  [{:no_touching, "~> 0.1", only: [:dev, :test]}]
end

Current issues

There are a lot of private functions that are currently shown as called because of macro expansion. Some of the really common ones are ignored directly in this library. Others, you can ignore by adding to your .ignore_private file.

In time I'm hoping to make this better, but for now adding things to .ignore_private is a good workaround.

Ignoring things

If you are seeing things that are coming up as being called but you want to ignore them, you can add an entry to a .ignore_private file in the root of your project. The file looks like this:

[
  {MyApp.Users, :private_fun, 2},
  Ecto,
  Absinthe
]

If you add a {module, function, arity} tuple to the list, any calls to that private function will be ignored. If you add just a single top level module to the list, all calls to any private functions in that namespace will be ignored. This is really handy for ignoring things like all private functions in Ecto that appear to be called because of macro expansion.