class RuboCop::Cop::Style::MethodDefParentheses

This cop checks for parentheses around the arguments in method definitions. Both instance and class/singleton methods are checked.

@example EnforcedStyle: require_parentheses (default)

# The `require_parentheses` style requires method definitions
# to always use parentheses

# bad
def bar num1, num2
  num1 + num2
end

def foo descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name
  do_something
end

# good
def bar(num1, num2)
  num1 + num2
end

def foo(descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name)
  do_something
end

@example EnforcedStyle: require_no_parentheses

# The `require_no_parentheses` style requires method definitions
# to never use parentheses

# bad
def bar(num1, num2)
  num1 + num2
end

def foo(descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name)
  do_something
end

# good
def bar num1, num2
  num1 + num2
end

def foo descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name
  do_something
end

@example EnforcedStyle: require_no_parentheses_except_multiline

# The `require_no_parentheses_except_multiline` style prefers no
# parentheses when method definition arguments fit on single line,
# but prefers parentheses when arguments span multiple lines.

# bad
def bar(num1, num2)
  num1 + num2
end

def foo descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name
  do_something
end

# good
def bar num1, num2
  num1 + num2
end

def foo(descriptive_var_name,
        another_descriptive_var_name,
        last_descriptive_var_name)
  do_something
end

Constants

MSG_MISSING
MSG_PRESENT

Public Instance Methods

autocorrect(node) click to toggle source
# File lib/rubocop/cop/style/method_def_parentheses.rb, line 112
def autocorrect(node)
  lambda do |corrector|
    if node.args_type?
      # offense is registered on args node when parentheses are unwanted
      corrector.replace(node.loc.begin, ' ')
      corrector.remove(node.loc.end)
    else
      args_expr = node.arguments.source_range
      args_with_space = range_with_surrounding_space(range: args_expr,
                                                     side: :left)
      just_space = range_between(args_with_space.begin_pos,
                                 args_expr.begin_pos)
      corrector.replace(just_space, '(')
      corrector.insert_after(args_expr, ')')
    end
  end
end
on_def(node) click to toggle source
# File lib/rubocop/cop/style/method_def_parentheses.rb, line 95
def on_def(node)
  args = node.arguments

  if require_parentheses?(args)
    if arguments_without_parentheses?(node)
      missing_parentheses(node)
    else
      correct_style_detected
    end
  elsif parentheses?(args)
    unwanted_parentheses(args)
  else
    correct_style_detected
  end
end
Also aliased as: on_defs
on_defs(node)
Alias for: on_def

Private Instance Methods

arguments_without_parentheses?(node) click to toggle source
# File lib/rubocop/cop/style/method_def_parentheses.rb, line 138
def arguments_without_parentheses?(node)
  node.arguments? && !parentheses?(node.arguments)
end
missing_parentheses(node) click to toggle source
# File lib/rubocop/cop/style/method_def_parentheses.rb, line 142
def missing_parentheses(node)
  location = node.arguments.source_range

  add_offense(node, location: location, message: MSG_MISSING) do
    unexpected_style_detected(:require_no_parentheses)
  end
end
require_parentheses?(args) click to toggle source
# File lib/rubocop/cop/style/method_def_parentheses.rb, line 132
def require_parentheses?(args)
  style == :require_parentheses ||
    (style == :require_no_parentheses_except_multiline &&
     args.multiline?)
end
unwanted_parentheses(args) click to toggle source
# File lib/rubocop/cop/style/method_def_parentheses.rb, line 150
def unwanted_parentheses(args)
  add_offense(args, message: MSG_PRESENT) do
    unexpected_style_detected(:require_parentheses)
  end
end