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Class: RuboCop::Cop::Style::RedundantConstantBase

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

Overview

Avoid redundant :: prefix on a constant.

How Ruby searches constants is a bit complicated, and it can often be difficult to understand from the code whether the :: is intended or not. Where Module.nesting is empty, there is no need to prepend ::, so it would be nice to consistently avoid such meaningless :: prefix to avoid confusion.

Note
 This cop is disabled if Lint/ConstantResolution cop is enabled, to prevent conflicting rules. This is because it respects user configurations that want to enable Lint/ConstantResolution cop which is disabled by default.

When AllCops/UseProjectIndex is enabled and the rubydex gem is installed, a leading :: inside a namespace is also reported when the constant provably resolves to the same declaration with and without the base, i.e. nothing in the surrounding nesting shadows it.

Examples:

# bad
::Const

# good
Const

# bad
class << self
  ::Const
end

# good
class << self
  Const
end

# good
class A
  ::Const
end

# good
module A
  ::Const
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ProjectIndexHelp - Included

BUILTIN_DOCUMENT_URI, FILE_URI_PREFIX, WINDOWS_DRIVE_PREFIX

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

support_autocorrect?

::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, #project_index, #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::ProjectIndexHelp - Included

#external_dependency_checksum, #compute_project_index_signature,
#definitions_in_other_files

Returns the definitions among definitions that live in a file other than the one being inspected, ordered by path and line.
#indexed_singleton_member

A namespace without any singleton method has no singleton-class declaration of its own, so the lookup starts from the first ancestor that has one; its find_member covers the rest of the chain.
#indexed_singleton_of

The declaration of `declaration’s singleton class, or nil when no singleton method is defined on it anywhere in the project.
#inherited_index_member?

Whether an ancestor of scope other than scope itself defines member_name.
#lexical_nesting_of

The lexical nesting the node’s constants resolve through, outermost first.
#prior_definition_in_other_file, #project_index_signature,
#resolve_constant_in_index

Resolves a constant node the way Ruby does: the first segment through the lexical nesting and every following segment inside the previous one.
#same_file?

::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, #matches_absolute_include_pattern?, #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

Instance Attribute Details

#lint_constant_resolution_cop_enabled? ⇒ Boolean (readonly, private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 95



def lint_constant_resolution_cop_enabled?
  lint_constant_resolution_config.fetch('Enabled', false)
end


  







Instance Method Details



  

    #bad?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 103



def bad?(node)
  module_nesting_ancestors_of(node).none?
end


  








  

    #first_constant_segment(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 88



def first_constant_segment(node)
  parent = node.parent
  return nil unless parent&.const_type?

  parent.short_name.to_s
end


  








  

    #lint_constant_resolution_config   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 99



def lint_constant_resolution_config
  config.for_cop('Lint/ConstantResolution')
end


  








  

    #module_nesting_ancestors_of(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 107



def module_nesting_ancestors_of(node)
  node.each_ancestor(:class, :module).reject do |ancestor|
    ancestor.class_type? && used_in_super_class_part?(node, class_node: ancestor)
  end
end


  








  

    #on_cbase(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 54



def on_cbase(node)
  return if lint_constant_resolution_cop_enabled?
  return unless bad?(node) || provably_unshadowed?(node)

  add_offense(node) do |corrector|
    corrector.remove(node)
  end
end


  








  

    #provably_unshadowed?(node)  ⇒ Boolean  (private)
  



  

    


When AllCops/UseProjectIndex is enabled, :: inside a namespace is
also redundant when the first constant segment resolves to the same
declaration with and without the base, i.e. nothing in the
surrounding nesting shadows it.



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 69



def provably_unshadowed?(node)
  return false unless project_index
  return false unless (segment = first_constant_segment(node))

  nesting = module_nesting_ancestors_of(node)
            .map { |ancestor| ancestor.identifier.const_name }.reverse

  !nesting.empty? && same_resolution?(segment, nesting)
rescue StandardError
  false
end


  








  

    #same_resolution?(segment, nesting)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 81



def same_resolution?(segment, nesting)
  relative = project_index.resolve_constant(segment, nesting)
  absolute = project_index.resolve_constant(segment, [])

  !relative.nil? && !absolute.nil? && relative.name == absolute.name
end


  








  

    #used_in_super_class_part?(node, class_node:)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/redundant_constant_base.rb', line 113



def used_in_super_class_part?(node, class_node:)
  class_node.parent_class&.each_descendant(:cbase)&.any? do |descendant|
    descendant.equal?(node)
  end
end