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Class: RuboCop::Cop::Style::EmptyClassDefinition

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::RangeHelp, ::RuboCop::Cop::Alignment, ::RuboCop::Cop::ConfigurableEnforcedStyle, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/empty_class_definition.rb

Overview

Enforces consistent style for empty class definitions.

This cop can enforce either a two-line class definition or Class.new for classes with no body.

The supported styles are:

  • class_definition (default) - prefer two-line class definition over Class.new

  • class_new - prefer Class.new over class definition

Examples:

EnforcedStyle: class_definition

# bad
FooError = Class.new(StandardError)

# okish
class FooError < StandardError; end

# good
class FooError < StandardError
end

EnforcedStyle: class_new

# bad
class FooError < StandardError
end

# bad
class FooError < StandardError; end

# good
FooError = Class.new(StandardError)

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

SYMBOL_TO_STRING_CACHE

::RuboCop::Cop::Alignment - Included

SPACE

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

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::Alignment - Included

#column_delta

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#detected_style, #detected_style=, #no_acceptable_style?, #style_configured?

::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::RangeHelp - Included

#add_range,
#arguments_range

A range containing the first to the last argument of a method call or method definition.
#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::Alignment - Included

#check_alignment, #configured_indentation_width, #display_column, #each_bad_alignment, #end_of_line_comment, #indentation, #offset, #register_offense, #within?

::RuboCop::Cop::ConfigurableEnforcedStyle - Included

#alternative_style, #alternative_styles, #ambiguous_style_detected,
#conflicting_styles_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.
#correct_style_detected, #no_acceptable_style!, #opposite_style_detected, #style, #style_detected, #style_parameter_name, #supported_styles, #unexpected_style_detected,
#unrecognized_style_detected

Alias for ConfigurableEnforcedStyle#no_acceptable_style!.

::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, #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

#autocorrect_class_definition(corrector, node) (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 92



def autocorrect_class_definition(corrector, node)
  source_line = processed_source.buffer.source_line(node.loc.line)
  indent = source_line[/\A */]
  class_name = node.identifier.source
  parent_class = node.parent_class&.source
  range = range_by_whole_lines(node.source_range, include_final_newline: true)

  replacement = if parent_class
                  "#{indent}#{class_name} = Class.new(#{parent_class})\n"
                else
                  "#{indent}#{class_name} = Class.new\n"
                end

  corrector.replace(range, replacement)
end


  








  

    #autocorrect_class_new(corrector, node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 77



def autocorrect_class_new(corrector, node)
  indent = ' ' * node.loc.column
  class_name = node.name
  class_new_node = find_class_new_node(node.expression)
  parent_class = extract_parent_class(class_new_node)

  replacement = if parent_class
                  "class #{class_name} < #{parent_class}\n#{indent}end"
                else
                  "class #{class_name}\n#{indent}end"
                end

  corrector.replace(node, replacement)
end


  








  

    #chained_with_any_method?(expression_node, class_new_node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 129



def chained_with_any_method?(expression_node, class_new_node)
  return true unless expression_node == class_new_node

  false
end


  








  

    #class_new_assignment?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 49



def_node_matcher :class_new_assignment?, <<~PATTERN
  (casgn _ _ (send (const _ :Class) :new ...))
PATTERN


  








  

    #empty_class?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 135



def empty_class?(node)
  body = node.body
  return true unless body

  body.begin_type? && body.children.empty?
end


  








  

    #extract_parent_class(class_new_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 108



def extract_parent_class(class_new_node)
  first_arg = class_new_node.first_argument
  first_arg&.source
end


  








  

    #find_class_new_node(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 120



def find_class_new_node(node)
  return nil unless node.send_type?
  return nil unless node.receiver&.const_type?

  return node if node.receiver.const_name.to_sym == :Class && node.method?(:new)

  nil
end


  








  

    #on_casgn(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 53



def on_casgn(node)
  return unless style == :class_definition
  return unless node.expression

  class_new_node = find_class_new_node(node.expression)
  return if chained_with_any_method?(node.expression, class_new_node)
  return if variable_parent_class?(class_new_node)

  add_offense(node, message: MSG_CLASS_DEFINITION) do |corrector|
    autocorrect_class_new(corrector, node)
  end
end


  








  

    #on_class(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 66



def on_class(node)
  return unless style == :class_new
  return unless empty_class?(node)

  add_offense(node, message: MSG_CLASS_NEW) do |corrector|
    autocorrect_class_definition(corrector, node)
  end
end


  








  

    #variable_parent_class?(class_new_node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 113



def variable_parent_class?(class_new_node)
  first_arg = class_new_node.first_argument
  return false unless first_arg

  !first_arg.const_type?
end