Class: RuboCop::Cop::Lint::NumberedParameterAssignment

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/lint/numbered_parameter_assignment.rb

Overview

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.

Examples:


# bad
_1 = :value

# good
non_numbered_parameter_name = :value

Constant Summary collapse

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

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods inherited from Base

#add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, #cop_name, cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#on_lvasgn(node) ⇒ Object


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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