gitlab-ce/doc/development/backend/ruby_style_guide.md

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reference, dev	none	Development	To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments

Ruby style guide

This is a GitLab-specific style guide for Ruby code.

Generally, if a style is not covered by existing Rubocop rules or style guides, it shouldn't be a blocker. Before adding a new cop to enforce a given style, make sure to discuss it with your team. When the style is approved by a backend EM or by a BE staff eng, add a new section to this page to document the new rule. For every new guideline, add it in a new section and link the discussion from the section's version history note to provide context and serve as a reference.

Just because something is listed here does not mean it cannot be reopened for discussion.

Instance variable access using attr_reader

Introduced in GitLab 14.1.

Instance variables can be accessed in a variety of ways in a class:

# public
class Foo
  attr_reader :my_var

  def initialize(my_var)
    @my_var = my_var
  end

  def do_stuff
    puts my_var
  end
end

# private
class Foo
  def initialize(my_var)
    @my_var = my_var
  end

  private

  attr_reader :my_var

  def do_stuff
    puts my_var
  end
end

# direct
class Foo
  def initialize(my_var)
    @my_var = my_var
  end

  private

  def do_stuff
    puts @my_var
  end
end

Public attributes should only be used if they are accessed outside of the class. There is not a strong opinion on what strategy is used when attributes are only accessed internally, as long as there is consistency in related code.