123456789_123456789_123456789_123456789_123456789_

Class: RuboCop::Cop::Lint::ShadowingOuterLocalVariable

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/shadowing_outer_local_variable.rb

Overview

Checks for the use of local variable names from an outer scope in block arguments or block-local variables. This mirrors the warning given by ruby -cw prior to Ruby 2.6: "shadowing outer local variable - foo".

The cop is now disabled by default to match the upstream Ruby behavior. It’s useful, however, if you’d like to avoid shadowing variables from outer scopes, which some people consider an anti-pattern that makes it harder to keep track of what’s going on in a program.

Note
 Shadowing of variables in block passed to Ractor.new is allowed because Ractor should not access outer variables. eg. following style is encouraged: 
worker_id, pipe = env
Ractor.new(worker_id, pipe) do |worker_id, pipe|
end

Examples:

# bad
def some_method
  foo = 1

  2.times do |foo| # shadowing outer {foo}
    do_something(foo)
  end
end

# good
def some_method
  foo = 1

  2.times do |bar|
    do_something(bar)
  end
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.
.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.
.badge

Naming.
.callbacks_needed, .cop_name, .department,
.documentation_url

Returns a url to view this cops documentation online.
.exclude_from_registry

Call for abstract Cop classes.
.inherited,
.joining_forces

Override and return the Force class(es) you need to join.
.match?

Returns true if the cop name or the cop namespace matches any of the given names.
.new,
.requires_gem

Register a version requirement for the given gem name.
.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.
transform

Instance Attribute Summary

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #string_literals_frozen_by_default?, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

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

Instance Method Summary

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.
#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.
#begin_investigation

Called before any investigation.
#callbacks_needed,
#cop_config

Configuration Helpers.
#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:
#inspect,
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.
#name

Alias for Base#cop_name.
#offenses,
#on_investigation_end

Called after all on_…​
#on_new_investigation

Called before all on_…​
#on_other_file

Called instead of all on_…​
#parse

There should be very limited reasons for a Cop to do it’s own parsing.
#parser_engine,
#ready

Called between investigations.
#relevant_file?,
#target_gem_version

Returns a gems locked versions (i.e.
#target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.
#complete_investigation

Called to complete an investigation.
#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:
#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.
#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #string_continuation?, #surrounding_heredoc?, #surrounding_percent_array?

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

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

Class Method Details

.joining_forces

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 54



def self.joining_forces
  VariableForce
end


  







Instance Method Details



  

    #before_declaring_variable(variable, variable_table)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 58



def before_declaring_variable(variable, variable_table)
  return if variable.should_be_unused?
  return if ractor_block?(variable.scope.node)

  outer_local_variable = variable_table.find_variable(variable.name)
  return unless outer_local_variable
  return if variable_used_in_declaration_of_outer?(variable, outer_local_variable)
  return if same_conditions_node_different_branch?(variable, outer_local_variable)

  message = format(MSG, variable: variable.name)
  add_offense(variable.declaration_node, message: message)
end


  








  

    #find_conditional_node_from_ascendant(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 101



def find_conditional_node_from_ascendant(node)
  return unless (parent = node.parent)
  return parent if parent.conditional?

  find_conditional_node_from_ascendant(parent)
end


  








  

    #node_or_its_ascendant_conditional?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 108



def node_or_its_ascendant_conditional?(node)
  return true if node.conditional?

  !!find_conditional_node_from_ascendant(node)
end


  








  

    #ractor_block?(node)  
  

  [ GitHub ]


  

  


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



def_node_matcher :ractor_block?, <<~PATTERN
  (block (send (const nil? :Ractor) :new ...) ...)
PATTERN


  








  

    #same_conditions_node_different_branch?(variable, outer_local_variable)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 77



def same_conditions_node_different_branch?(variable, outer_local_variable)
  variable_node = variable_node(variable)
  return false unless node_or_its_ascendant_conditional?(variable_node)

  outer_local_variable_node =
    find_conditional_node_from_ascendant(outer_local_variable.declaration_node)
  return false unless outer_local_variable_node
  return false unless outer_local_variable_node.conditional?
  return true if variable_node == outer_local_variable_node

  outer_local_variable_node.if_type? &&
    variable_node == outer_local_variable_node.else_branch
end


  








  

    #variable_node(variable)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 91



def variable_node(variable)
  parent_node = variable.scope.node.parent

  if parent_node.when_type?
    parent_node.parent
  else
    parent_node
  end
end


  








  

    #variable_used_in_declaration_of_outer?(variable, outer_local_variable)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 73



def variable_used_in_declaration_of_outer?(variable, outer_local_variable)
  variable.scope.node.each_ancestor.any?(outer_local_variable.declaration_node)
end