Class: RuboCop::Cop::Style::SelfAssignment

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/self_assignment.rb


Enforces the use the shorthand for self-assignment.


# bad
x = x + 1

# good
x += 1

Constant Summary

::RuboCop::Cop::Base - Inherited


Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,

Returns if class supports autocorrect.


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


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



.callbacks_needed, .cop_name, .department,

Returns an url to view this cops documentation online.


Call for abstract Cop classes.


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


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


Register a version requirement for the given gem name.


::RuboCop::ExcludeLimit - Extended


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


Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::Base - Inherited


Adds an offense that has no particular location.


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.


Called before any investigation.


Configuration Helpers.

#cop_name, #excluded_file?,

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


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.


Alias for Base#cop_name.


Called after all on_…​


Called before all on_…​


Called instead of all on_…​


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


Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,

Reserved for Cop::Cop.


Called to complete an investigation.

#correct, #current_corrector,

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,

Actually private methods.


::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Class Method Details


[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 21

def self.autocorrect_incompatible_with

Instance Method Details

#apply_autocorrect(corrector, node, rhs, operator, new_rhs) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 94

def apply_autocorrect(corrector, node, rhs, operator, new_rhs)
  corrector.insert_before(node.loc.operator, operator)
  corrector.replace(rhs, new_rhs.source)

#autocorrect(corrector, node) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 74

def autocorrect(corrector, node)
  _var_name, rhs = *node

  if rhs.send_type?
    autocorrect_send_node(corrector, node, rhs)
  elsif rhs.operator_keyword?
    autocorrect_boolean_node(corrector, node, rhs)

#autocorrect_boolean_node(corrector, node, rhs) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 89

def autocorrect_boolean_node(corrector, node, rhs)
  _first_operand, second_operand = *rhs
  apply_autocorrect(corrector, node, rhs, rhs.loc.operator.source, second_operand)

#autocorrect_send_node(corrector, node, rhs) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 84

def autocorrect_send_node(corrector, node, rhs)
  _receiver, method_name, args = *rhs
  apply_autocorrect(corrector, node, rhs, method_name.to_s, args)

#check(node, var_type) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 39

def check(node, var_type)
  var_name, rhs = *node
  return unless rhs

  if rhs.send_type?
    check_send_node(node, rhs, var_name, var_type)
  elsif rhs.operator_keyword?
    check_boolean_node(node, rhs, var_name, var_type)

#check_boolean_node(node, rhs, var_name, var_type) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 62

def check_boolean_node(node, rhs, var_name, var_type)
  first_operand, _second_operand = *rhs

  target_node = s(var_type, var_name)
  return unless first_operand == target_node

  operator = rhs.loc.operator.source
  add_offense(node, message: format(MSG, method: operator)) do |corrector|
    autocorrect(corrector, node)

#check_send_node(node, rhs, var_name, var_type) (private)

[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 50

def check_send_node(node, rhs, var_name, var_type)
  receiver, method_name, *_args = *rhs
  return unless OPS.include?(method_name)

  target_node = s(var_type, var_name)
  return unless receiver == target_node

  add_offense(node, message: format(MSG, method: method_name)) do |corrector|
    autocorrect(corrector, node)


[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 33

def on_cvasgn(node)
  check(node, :cvar)


[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 29

def on_ivasgn(node)
  check(node, :ivar)


[ GitHub ]

# File 'lib/rubocop/cop/style/self_assignment.rb', line 25

def on_lvasgn(node)
  check(node, :lvar)