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Versions: 30
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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# This cop checks if each_with_object is called with an immutable
# argument. Since the argument is the object that the given block shall
# make calls on to build something based on the enumerable that
# each_with_object iterates over, an immutable argument makes no sense.
# It's definitely a bug.
#
# @example
#
# # bad
#
# sum = numbers.each_with_object(0) { |e, a| a += e }
#
# @example
#
# # good
#
# num = 0
# sum = numbers.each_with_object(num) { |e, a| a += e }
class EachWithObjectArgument < Base
MSG = 'The argument to each_with_object cannot be immutable.'
RESTRICT_ON_SEND = %i[each_with_object].freeze
def_node_matcher :each_with_object?, <<~PATTERN
({send csend} _ :each_with_object $_)
PATTERN
def on_send(node)
each_with_object?(node) do |arg|
return unless arg.immutable_literal?
add_offense(node)
end
end
alias on_csend on_send
end
end
end
end
Version data entries
30 entries across 30 versions & 2 rubygems