View Source Credo.Check.Refactor.VariableRebinding (Credo v1.7.5)

Basics

This check is disabled by default.

Learn how to enable it via .credo.exs.

This check is tagged :controversial

This means that this check is more opinionated than others and not for everyone's taste.

This check has a base priority of 0 and works with any version of Elixir.

Explanation

You might want to refrain from rebinding variables.

Although technically fine, rebinding to the same name can lead to less precise naming.

Consider this example:

def find_a_good_time do
  time = MyApp.DateTime.now
  time = MyApp.DateTime.later(time, 5, :days)
  {:ok, time} = verify_available_time(time)

  time
end

While there is nothing wrong with this, many would consider the following implementation to be easier to comprehend:

def find_a_good_time do
  today = DateTime.now
  proposed_time = DateTime.later(today, 5, :days)
  {:ok, verified_time} = verify_available_time(proposed_time)

  verified_time
end

In some rare cases you might really want to rebind a variable. This can be enabled "opt-in" on a per-variable basis by setting the :allow_bang option to true and adding a bang suffix sigil to your variable.

def uses_mutating_parameters(params!) do
  params! = do_a_thing(params!)
  params! = do_another_thing(params!)
  params! = do_yet_another_thing(params!)
end

Check-Specific Parameters

Use the following parameters to configure this check:

:allow_bang

Variables with a bang suffix will be ignored.

This parameter defaults to false.

General Parameters

Like with all checks, general params can be applied.

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