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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# This cop checks unexpected overrides of the `Struct` built-in methods
# via `Struct.new`.
#
# @example
# # bad
# Bad = Struct.new(:members, :clone, :count)
# b = Bad.new([], true, 1)
# b.members #=> [] (overriding `Struct#members`)
# b.clone #=> true (overriding `Object#clone`)
# b.count #=> 1 (overriding `Enumerable#count`)
#
# # good
# Good = Struct.new(:id, :name)
# g = Good.new(1, "foo")
# g.members #=> [:id, :name]
# g.clone #=> #<struct Good id=1, name="foo">
# g.count #=> 2
#
class StructNewOverride < Base
MSG = '`%<member_name>s` member overrides `Struct#%<method_name>s`' \
' and it may be unexpected.'
STRUCT_METHOD_NAMES = Struct.instance_methods
STRUCT_MEMBER_NAME_TYPES = %i[sym str].freeze
def_node_matcher :struct_new, <<~PATTERN
(send
(const ${nil? cbase} :Struct) :new ...)
PATTERN
def on_send(node)
return unless struct_new(node) do
node.arguments.each_with_index do |arg, index|
# Ignore if the first argument is a class name
next if index.zero? && arg.str_type?
# Ignore if the argument is not a member name
next unless STRUCT_MEMBER_NAME_TYPES.include?(arg.type)
member_name = arg.value
next unless STRUCT_METHOD_NAMES.include?(member_name.to_sym)
message = format(MSG, member_name: member_name.inspect,
method_name: member_name.to_s)
add_offense(arg, message: message)
end
end
end
end
end
end
end
Version data entries
4 entries across 4 versions & 2 rubygems