View Source Credo.Check.Readability.PredicateFunctionNames (Credo v1.7.8)

Basics

This check is enabled by default.

Learn how to disable it via .credo.exs.

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

Explanation

Predicate functions/macros should be named accordingly:

• For functions, they should end in a question mark.

  # preferred
  
  defp user?(cookie) do
  end
  
  defp has_attachment?(mail) do
  end
  
  # NOT preferred
  
  defp is_user?(cookie) do
  end
  
  defp is_user(cookie) do
  end

• For guard-safe macros they should have the prefix is_ and not end in a question mark.

  # preferred
  
  defmacro is_user(cookie) do
  end
  
  # NOT preferred
  
  defmacro is_user?(cookie) do
  end
  
  defmacro user?(cookie) do
  end

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.