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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::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 standard class definition or Class.new for classes with no body.

The supported styles are:

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

  • class_new - prefer Class.new over class definition

One difference between the two styles is that the Class.new form does not make the subclass name available to the base class’s inherited callback. For this reason, EnforcedStyle: class_definition is set as the default style. Class definitions without a superclass, which are not involved in inheritance, are not detected. This ensures safe detection regardless of the applied style. This avoids overlapping responsibilities with the Lint/EmptyClass cop.

Examples:

EnforcedStyle: class_keyword (default)

# 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

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::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::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 88



def autocorrect_class_definition(corrector, node)
  class_name = node.identifier.source
  parent_class_name = node.parent_class.source

  corrector.replace(node, "#{class_name} = Class.new(#{parent_class_name})")
end


  








  

    #autocorrect_class_new(corrector, node, class_new_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 80



def autocorrect_class_new(corrector, node, class_new_node)
  indent = ' ' * node.loc.column
  class_name = node.name
  parent_class_name = class_new_node.first_argument.source

  corrector.replace(node, "class #{class_name} < #{parent_class_name}\n#{indent}end")
end


  








  

    #class_new_assignment(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 54



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


  








  

    #on_casgn(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 58



def on_casgn(node)
  return unless %i[class_keyword class_definition].include?(style)
  return unless (class_new_node = class_new_assignment(node))
  return if (arg = class_new_node.first_argument) && !arg.const_type?

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


  








  

    #on_class(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/empty_class_definition.rb', line 68



def on_class(node)
  return unless style == :class_new
  return unless node.parent_class
  return if (body = node.body) && !body.children.empty?

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