Class: RuboCop::Cop::Lint::UnderscorePrefixedVariableName

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

Overview

This cop checks for underscore-prefixed variables that are actually used.

Since block keyword arguments cannot be arbitrarily named at call sites, the `AllowKeywordBlockArguments` will allow use of underscore- prefixed block keyword arguments.

Examples:

AllowKeywordBlockArguments: false (default)


# bad

[1, 2, 3].each do |_num|
  do_something(_num)
end

query(:sales) do |_id:, revenue:, cost:|
  {_id: _id, profit: revenue - cost}
end

# good

[1, 2, 3].each do |num|
  do_something(num)
end

[1, 2, 3].each do |_num|
  do_something # not using `_num`
end

AllowKeywordBlockArguments: true


# good

query(:sales) do |_id:, revenue:, cost:|
  {_id: _id, profit: revenue - cost}
end

Constant Summary collapse

MSG =
'Do not use prefix `_` for a variable that is used.'

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Class Method Summary collapse

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, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

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

Class Method Details

.joining_forcesObject


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# File 'lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb', line 46

def self.joining_forces
  VariableForce
end

Instance Method Details

#after_leaving_scope(scope, _variable_table) ⇒ Object


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# File 'lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb', line 50

def after_leaving_scope(scope, _variable_table)
  scope.variables.each_value do |variable|
    check_variable(variable)
  end
end

#check_variable(variable) ⇒ Object


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# File 'lib/rubocop/cop/lint/underscore_prefixed_variable_name.rb', line 56

def check_variable(variable)
  return unless variable.should_be_unused?
  return if variable.references.none?(&:explicit?)
  return if allowed_keyword_block_argument?(variable)

  node = variable.declaration_node

  location = if node.match_with_lvasgn_type?
               node.children.first.source_range
             else
               node.loc.name
             end

  add_offense(location)
end