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Class: RuboCop::Cop::Lint::MissingSuper

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/missing_super.rb

Overview

Checks for the presence of constructors and lifecycle callbacks without calls to super.

This cop does not consider method_missing (and respond_to_missing?) because in some cases it makes sense to overtake what is considered a missing method. In other cases, the theoretical ideal handling could be challenging or verbose for no actual gain.

Autocorrection is not supported because the position of super cannot be determined automatically.

Object and BasicObject are allowed by this cop because of their stateless nature. However, sometimes you might want to allow other parent classes from this cop, for example in the case of an abstract class that is not meant to be called with super. In those cases, you can use the AllowedParentClasses option to specify which classes should be allowed in addition to Object and BasicObject.

Examples:

# bad
class Employee < Person
  def initialize(name, salary)
    @salary = salary
  end
end

# good
class Employee < Person
  def initialize(name, salary)
    super(name)
    @salary = salary
  end
end

# bad
Employee = Class.new(Person) do
  def initialize(name, salary)
    @salary = salary
  end
end

# good
Employee = Class.new(Person) do
  def initialize(name, salary)
    super(name)
    @salary = salary
  end
end

# bad
class Parent
  def self.inherited(base)
    do_something
  end
end

# good
class Parent
  def self.inherited(base)
    super
    do_something
  end
end

# good
class ClassWithNoParent
  def initialize
    do_something
  end
end

AllowedParentClasses: [MyAbstractClass]

# good
class MyConcreteClass < MyAbstractClass
  def initialize
    do_something
  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_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, #max_line_length,
#range_by_lines

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

#allowed_class?(node) ⇒ Boolean (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 149



def allowed_class?(node)
  allowed_classes.include?(node.const_name)
end


  








  

    #allowed_classes   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 153



def allowed_classes
  @allowed_classes ||= STATELESS_CLASSES + cop_config.fetch('AllowedParentClasses', [])
end


  








  

    #callback_method_def?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 127



def callback_method_def?(node)
  return false unless CALLBACKS.include?(node.method_name)

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


  








  

    #class_new_block(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 99



def_node_matcher :class_new_block, <<~RUBY
  ({block numblock}
    (send
      (const {nil? cbase} :Class) :new $_) ...)
RUBY


  








  

    #contains_super?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 133



def contains_super?(node)
  node.each_descendant(:super, :zsuper).any?
end


  








  

    #inside_class_with_stateful_parent?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 137



def inside_class_with_stateful_parent?(node)
  if (block_node = node.each_ancestor(:block, :numblock).first)
    return false unless (super_class = class_new_block(block_node))

    !allowed_class?(super_class)
  elsif (class_node = node.each_ancestor(:class).first)
    class_node.parent_class && !allowed_class?(class_node.parent_class)
  else
    false
  end
end


  








  

    #offender?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 123



def offender?(node)
  (node.method?(:initialize) || callback_method_def?(node)) && !contains_super?(node)
end


  








  

    #on_def(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 105



def on_def(node)
  return unless offender?(node)

  if node.method?(:initialize) && inside_class_with_stateful_parent?(node)
    add_offense(node, message: CONSTRUCTOR_MSG)
  elsif callback_method_def?(node)
    add_offense(node, message: CALLBACK_MSG)
  end
end


  








  

    #on_defs(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 115



def on_defs(node)
  return if !callback_method_def?(node) || contains_super?(node)

  add_offense(node, message: CALLBACK_MSG)
end