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# frozen_string_literal: true
module RuboCop
module Cop
module Performance
# This cop checks for `OpenStruct.new` calls.
# Instantiation of an `OpenStruct` invalidates
# Ruby global method cache as it causes dynamic method
# definition during program runtime.
# This could have an effect on performance,
# especially in case of single-threaded
# applications with multiple `OpenStruct` instantiations.
#
# @example
# # bad
# class MyClass
# def my_method
# OpenStruct.new(my_key1: 'my_value1', my_key2: 'my_value2')
# end
# end
#
# # good
# class MyClass
# MyStruct = Struct.new(:my_key1, :my_key2)
# def my_method
# MyStruct.new('my_value1', 'my_value2')
# end
# end
#
class OpenStruct < Cop
MSG = 'Consider using `Struct` over `OpenStruct` ' \
'to optimize the performance.'
def_node_matcher :open_struct, <<~PATTERN
(send (const {nil? cbase} :OpenStruct) :new ...)
PATTERN
def on_send(node)
open_struct(node) do
add_offense(node, location: :selector)
end
end
end
end
end
end
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