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Class: RuboCop::Cop::Lint::DisjunctiveAssignmentInConstructor

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::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/disjunctive_assignment_in_constructor.rb

Overview

Checks constructors for disjunctive assignments (||=) that should be plain assignments.

So far, this cop is only concerned with disjunctive assignment of instance variables.

In ruby, an instance variable is nil until a value is assigned, so the disjunction is unnecessary. A plain assignment has the same effect.

Examples:

# bad
def initialize
  @x ||= 1
end

# good
def initialize
  @x = 1
end

Cop Safety Information:

  • This cop is unsafe because it can register a false positive when a method is redefined in a subclass that calls super. For example:

    class Base
  def initialize
    @config ||= 'base'
  end
end

class Derived < Base
  def initialize
    @config = 'derived'
    super
  end
end

    Without the disjunctive assignment, Derived will be unable to override the value for @config.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

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, #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

#check(node) (private)

Parameters:

  • node (DefNode) —

    a constructor definition

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/disjunctive_assignment_in_constructor.rb', line 60



def check(node)
  return unless node.method?(:initialize)

  check_body(node.body)
end


  








  

    #check_body(body)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/disjunctive_assignment_in_constructor.rb', line 66



def check_body(body)
  return if body.nil?

  case body.type
  when :begin
    check_body_lines(body.child_nodes)
  else
    check_body_lines([body])
  end
end


  








  

    #check_body_lines(lines)   (private)
  



  

    
  





  
Parameters:


    
  
  • 
    lines
    (Array)
—    
    

    the logical lines of the constructor
    

    
  
    • 





  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/disjunctive_assignment_in_constructor.rb', line 78



def check_body_lines(lines)
  lines.each do |line|
    case line.type
    when :or_asgn
      check_disjunctive_assignment(line)
    else
      # Once we encounter something other than a disjunctive
      # assignment, we cease our investigation, because we can't be
      # certain that any future disjunctive assignments are offensive.
      # You're off the case, detective!
      break
    end
  end
end


  








  

    #check_disjunctive_assignment(node)   (private)
  



  

    


Add an offense if the LHS of the given disjunctive assignment is
an instance variable.






For now, we only care about assignments to instance variables.



  





  
Parameters:


    
  
  • 
    node
    (Node)
—    
    

    a disjunctive assignment
    

    
  
    • 





  [ GitHub ]


  

  


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



def check_disjunctive_assignment(node)
  lhs = node.child_nodes.first
  return unless lhs.ivasgn_type?

  add_offense(node.loc.operator) do |corrector|
    corrector.replace(node.loc.operator, '=')
  end
end


  








  

    #on_def(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/disjunctive_assignment_in_constructor.rb', line 53



def on_def(node)
  check(node)
end