lib/rubocop/cop/naming/binary_operator_parameter_name.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Naming
# Makes sure that certain binary operator methods have their
# sole parameter named `other`.
#
# @example
#
# # bad
# def +(amount); end
#
# # good
# def +(other); end
class BinaryOperatorParameterName < Base
extend AutoCorrector
MSG = 'When defining the `%<opr>s` operator, name its argument `other`.'
OP_LIKE_METHODS = %i[eql? equal?].freeze
EXCLUDED = %i[+@ -@ [] []= << === ` =~].freeze
# @!method op_method_candidate?(node)
def_node_matcher :op_method_candidate?, <<~PATTERN
(def [#op_method? $_] (args $(arg [!:other !:_other])) _)
PATTERN
def on_def(node)
op_method_candidate?(node) do |name, arg|
add_offense(arg, message: format(MSG, opr: name)) do |corrector|
corrector.replace(arg, 'other')
node.each_descendant(:lvar, :lvasgn) do |lvar|
lvar_location = lvar.loc.name
next unless lvar_location.source == arg.source
corrector.replace(lvar_location, 'other')
end
end
end
end
private
def op_method?(name)
return false if EXCLUDED.include?(name)
!/\A[[:word:]]/.match?(name) || OP_LIKE_METHODS.include?(name)
end
end
end
end
end