Methods

Methods

Method definitions

• Use def with parentheses when there are
  parameters. Omit the parentheses when the method doesn’t accept any
  parameters.[link]

   def some_method
     # body omitted
   end

   def some_method_with_parameters(arg1, arg2)
     # body omitted
   end

• Do not use default positional arguments.
  Use keyword arguments (if available - in Ruby 2.0 or later) or an options
  hash instead.[link]

  # bad
  def obliterate(things, gently = true, except = [], at = Time.now)
    ...
  end

  # good
  def obliterate(things, gently: true, except: [], at: Time.now)
    ...
  end

  # good
  def obliterate(things, options = {})
    options = {
      :gently => true, # obliterate with soft-delete
      :except => [], # skip obliterating these things
      :at => Time.now, # don't obliterate them until later
    }.merge(options)

    ...
  end

• Avoid single-line methods. Although
  they are somewhat popular in the wild, there are a few peculiarities about
  their definition syntax that make their use undesirable.
  [link]

  # bad
  def too_much; something; something_else; end

  # good
  def some_method
    # body
  end

Method calls

Use parentheses for a method call:

• If the method returns a value.
  [link]

  # bad
  @current_user = User.find_by_id 1964192

  # good
  @current_user = User.find_by_id(1964192)

• If the first argument to the method uses
  parentheses.[link]

  # bad
  put! (x + y) % len, value

  # good
  put!((x + y) % len, value)

• Never put a space between a method name and
  the opening parenthesis.[link]

  # bad
  f (3 + 2) + 1

  # good
  f(3 + 2) + 1

• Omit parentheses for a method call if the
  method accepts no arguments.[link]

  # bad
  nil?()

  # good
  nil?

• If the method doesn’t return a value (or we
  don’t care about the return), parentheses are optional. (Especially if the
  arguments overflow to multiple lines, parentheses may add readability.)
  [link]

  # okay
  render(:partial => 'foo')

  # okay
  render :partial => 'foo'

In either case:

• If a method accepts an options hash as the
  last argument, do not use { } during invocation.
  [link]

  # bad
  get '/v1/reservations', { :id => 54875 }

  # good
  get '/v1/reservations', :id => 54875