class RuboCop::Cop::Lint::NumberedParameterAssignment
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
Constants
- LVAR_MSG
- NUMBERED_PARAMETER_RANGE
- NUM_PARAM_MSG
Public Instance Methods
on_lvasgn(node)
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# File lib/rubocop/cop/lint/numbered_parameter_assignment.rb, line 35 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