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Class: RuboCop::Cop::Style::MissingRespondToMissing

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::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/missing_respond_to_missing.rb

Overview

Checks for the presence of method_missing without also defining respond_to_missing?.

Not defining respond_to_missing? will cause metaprogramming methods like respond_to? to behave unexpectedly:

[source,ruby]

class StringDelegator def initialize(string) @string = string end

def method_missing(name, *args)
@string.send(name, *args)
end

end

delegator = StringDelegator.new("foo")

Claims to not respond to upcase.

delegator.respond_to?(:upcase) # => false

But you can call it.

delegator.upcase # => FOO

When AllCops/UseProjectIndex is enabled and the rubydex gem is installed, respond_to_missing? defined in another definition of the same class or module (e.g. a reopening in another file) also satisfies the check.

Examples:

# bad
def method_missing(name, *args)
  if @delegate.respond_to?(name)
    @delegate.send(name, *args)
  else
    super
  end
end

# good
def respond_to_missing?(name, include_private)
  @delegate.respond_to?(name) || super
end

def method_missing(name, *args)
  if @delegate.respond_to?(name)
    @delegate.send(name, *args)
  else
    super
  end
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::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 Method Details

#enclosing_scope(node) (private)

The class/module/class << self body that lexically contains node, or nil when node is defined at the top level.

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/missing_respond_to_missing.rb', line 109



def enclosing_scope(node)
  node.each_ancestor(:class, :module, :sclass).first
end


  








  

    #implements_respond_to_missing?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/missing_respond_to_missing.rb', line 97



def implements_respond_to_missing?(node)
  scope = enclosing_scope(node)
  search_root = scope || node.parent
  return false unless search_root

  search_root.each_descendant(node.type).any? do |descendant|
    descendant.method?(:respond_to_missing?) && enclosing_scope(descendant).equal?(scope)
  end
end


  








  

    #on_def(node)  
    Also known as: #on_defs
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/missing_respond_to_missing.rb', line 64



def on_def(node)
  return unless node.method?(:method_missing)
  return if implements_respond_to_missing?(node)
  return if respond_to_missing_elsewhere?(node)

  add_offense(node)
end


  








  

    #on_defs(node)  
  



  

    


Alias for #on_def.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/missing_respond_to_missing.rb', line 71



alias on_defs on_def


  








  

    #respond_to_missing_elsewhere?(node)  ⇒ Boolean  (private)
  



  

    


When AllCops/UseProjectIndex is enabled, respond_to_missing?
defined in another definition of the same class or module (e.g. a
reopening in another file) also satisfies the check. Ancestors are
not consulted: overriding method_missing warrants a matching
respond_to_missing? for the same class.



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/missing_respond_to_missing.rb', line 80



def respond_to_missing_elsewhere?(node)
  return false unless project_index
  return false unless (namespace_node = node.each_ancestor(:class, :module).first)

  declaration = resolve_constant_in_index(namespace_node.identifier)
  return false unless declaration.is_a?(Rubydex::Namespace)

  scope = singleton_definition?(node) ? indexed_singleton_of(declaration) : declaration
  !scope&.member('respond_to_missing?()').nil?
rescue StandardError
  false
end


  








  

    #singleton_definition?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/missing_respond_to_missing.rb', line 93



def singleton_definition?(node)
  node.defs_type? || node.each_ancestor(:sclass, :class, :module).first&.sclass_type?
end