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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# This cop checks for uses of numbered parameter assignment.
# It emulates the following warning in Ruby 2.7:
#
# % ruby -ve '_1 = :value'
# ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-darwin19]
# -e:1: warning: `_1' is reserved for numbered parameter; consider another name
#
# Assigning to a numbered parameter (from `_1` to `_9`) causes an error in Ruby 3.0.
#
# % ruby -ve '_1 = :value'
# ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-darwin19]
# -e:1: _1 is reserved for numbered parameter
#
# NOTE: The parametered parameters are from `_1` to `_9`. This cop checks `_0`, and over `_10`
# as well to prevent confusion.
#
# @example
#
# # bad
# _1 = :value
#
# # good
# non_numbered_parameter_name = :value
#
class NumberedParameterAssignment < Base
NUM_PARAM_MSG = '`_%<number>s` is reserved for numbered parameter; consider another name.'
LVAR_MSG = '`_%<number>s` is similar to numbered parameter; consider another name.'
NUMBERED_PARAMETER_RANGE = (1..9).freeze
def on_lvasgn(node)
lhs, _rhs = *node
return unless /\A_(\d+)\z/ =~ lhs
number = Regexp.last_match(1).to_i
template = NUMBERED_PARAMETER_RANGE.include?(number) ? NUM_PARAM_MSG : LVAR_MSG
add_offense(node, message: format(template, number: number))
end
end
end
end
end
Version data entries
21 entries across 21 versions & 4 rubygems