View Source Credo.Check.Readability.WithCustomTaggedTuple (Credo v1.7.4)

Basics

This check is disabled by default.

Learn how to enable it via .credo.exs.

This check has a base priority of low and works with any version of Elixir.

Explanation

Avoid using custom tags for error reporting from with macros.

This code injects placeholder tags such as :resource and :authz for the purpose of error reporting.

with {:resource, {:ok, resource}} <- {:resource, Resource.fetch(user)},
     {:authz, :ok} <- {:authz, Resource.authorize(resource, user)} do
  do_something_with(resource)
else
  {:resource, _} -> {:error, :not_found}
  {:authz, _} -> {:error, :unauthorized}
end

Instead, extract each validation into a separate helper function which returns error information immediately:

defp find_resource(user) do
  with :error <- Resource.fetch(user), do: {:error, :not_found}
end

defp authorize(resource, user) do
  with :error <- Resource.authorize(resource, user), do: {:error, :unauthorized}
end

At this point, the validation chain in with becomes clearer and easier to understand:

with {:ok, resource} <- find_resource(user),
     :ok <- authorize(resource, user),
     do: do_something(user)

Like all Readability issues, this one is not a technical concern. But you can improve the odds of others reading and liking your code by making it easier to follow.

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.