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Class: RuboCop::Cop::Style::RedundantInitialize

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:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/redundant_initialize.rb

Overview

Checks for initialize methods that are redundant.

An initializer is redundant if it does not do anything, or if it only calls super with the same arguments given to it. If the initializer takes an argument that accepts multiple values (restarg, kwrestarg, etc.) it will not register an offense, because it allows the initializer to take a different number of arguments as its superclass potentially does.

Note
If an initializer argument has a default value, RuboCop assumes it to not be redundant.
Note
Empty initializers are registered as offenses, but it is possible to purposely create an empty initialize method to override a superclass’s initializer.

Examples:

# bad
def initialize
end

# bad
def initialize
  super
end

# bad
def initialize(a, b)
  super
end

# bad
def initialize(a, b)
  super(a, b)
end

# good
def initialize
  do_something
end

# good
def initialize
  do_something
  super
end

# good (different number of parameters)
def initialize(a, b)
  super(a)
end

# good (default value)
def initialize(a, b = 5)
  super
end

# good (default value)
def initialize(a, b: 5)
  super
end

# good (changes the parameter requirements)
def initialize(*)
end

# good (changes the parameter requirements)
def initialize(**)
end

# good (changes the parameter requirements)
def initialize(...)
end

AllowComments: true (default)

# good
def initialize
  # Overriding to negate superclass `initialize` method.
end

AllowComments: false

# bad
def initialize
  # Overriding to negate superclass `initialize` method.
end

Cop Safety Information:

  • This cop is unsafe because if subclass overrides initialize method with a different arity than superclass.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::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 an 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

Instance Method Summary

::RuboCop::Cop::RangeHelp - Included

#add_range, #column_offset_between,
#contents_range

A range containing only the contents of a literal with delimiters (e.g.

#directions,
#effective_column

Returns the column attribute of the range, except if the range is on the first line and there’s a byte order mark at the beginning of that line, in which case 1 is subtracted from the column value.

#final_pos, #move_pos, #move_pos_str, #range_between, #range_by_whole_lines, #range_with_comments, #range_with_comments_and_lines, #range_with_surrounding_comma, #range_with_surrounding_space, #source_range

::RuboCop::Cop::CommentsHelp - Included

#comments_contain_disables?, #comments_in_range, #contains_comments?, #source_range_with_comment, #begin_pos_with_comment, #buffer, #end_position_for,
#find_end_line

Returns the end line of a node, which might be a comment and not part of the AST End line is considered either the line at which another node starts, or the line at which the parent node ends.

#start_line_position

::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

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Instance Method Details

#acceptable?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 134

def acceptable?(node)
  !node.method?(:initialize) || forwards?(node) || allow_comments?(node)
end

#allow_comments?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 142

def allow_comments?(node)
  return false unless cop_config['AllowComments']

  contains_comments?(node) && !comments_contain_disables?(node, name)
end

#forwards?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 138

def forwards?(node)
  node.arguments.each_child_node(:restarg, :kwrestarg, :forward_args, :forward_arg).any?
end

#initialize_forwards?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 106

def_node_matcher :initialize_forwards?, <<~PATTERN
  (def _ (args $arg*) $({super zsuper} ...))
PATTERN

#on_def(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 110

def on_def(node)
  return if acceptable?(node)

  if node.body.nil?
    register_offense(node, MSG_EMPTY)
  else
    return if node.body.begin_type?

    if (args, super_node = initialize_forwards?(node))
      return unless same_args?(super_node, args)

      register_offense(node, MSG)
    end
  end
end

#register_offense(node, message) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 128

def register_offense(node, message)
  add_offense(node, message: message) do |corrector|
    corrector.remove(range_by_whole_lines(node.source_range, include_final_newline: true))
  end
end

#same_args?(super_node, args) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/redundant_initialize.rb', line 148

def same_args?(super_node, args)
  return true if super_node.zsuper_type?

  args.map(&:name) == super_node.arguments.map { |a| a.children[0] }
end