123456789_123456789_123456789_123456789_123456789_

Class: RuboCop::Cop::Style::StaticClass

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/static_class.rb

Overview

Checks for places where classes with only class methods can be replaced with a module. Classes should be used only when it makes sense to create instances out of them.

Examples:

# bad
class SomeClass
  def self.some_method
    # body omitted
  end

  def self.some_other_method
    # body omitted
  end
end

# good
module SomeModule
  module_function

  def some_method
    # body omitted
  end

  def some_other_method
    # body omitted
  end
end

# good - has instance method
class SomeClass
  def instance_method; end
  def self.class_method; end
end

Cop Safety Information:

  • This cop is unsafe, because it is possible that this class is a parent for some other subclass, monkey-patched with instance methods or a dummy instance is instantiated from it somewhere.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::RangeHelp - Included

BYTE_ORDER_MARK, NOT_GIVEN

::RuboCop::Cop::VisibilityHelp - Included

VISIBILITY_SCOPES

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::VisibilityHelp - Included

::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::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

#autocorrect(corrector, class_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/static_class.rb', line 64

def autocorrect(corrector, class_node)
  corrector.replace(class_node.loc.keyword, 'module')
  corrector.insert_after(class_node.loc.name, "\nmodule_function\n")

  class_elements(class_node).each do |node|
    if node.defs_type?
      autocorrect_def(corrector, node)
    elsif node.sclass_type?
      autocorrect_sclass(corrector, node)
    end
  end
end

#autocorrect_def(corrector, node) (private)

[ GitHub ]

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

def autocorrect_def(corrector, node)
  corrector.remove(
    range_between(node.receiver.source_range.begin_pos, node.loc.name.begin_pos)
  )
end

#autocorrect_sclass(corrector, node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/static_class.rb', line 83

def autocorrect_sclass(corrector, node)
  corrector.remove(
    range_between(node.loc.keyword.begin_pos, node.identifier.source_range.end_pos)
  )
  corrector.remove(node.loc.end)
end

#class_convertible_to_module?(class_node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/static_class.rb', line 90

def class_convertible_to_module?(class_node)
  nodes = class_elements(class_node)
  return false if nodes.empty?

  nodes.all? do |node|
    (node_visibility(node) == :public && node.defs_type?) ||
      sclass_convertible_to_module?(node) ||
      node.equals_asgn? ||
      extend_call?(node)
  end
end

#class_elements(class_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/static_class.rb', line 114

def class_elements(class_node)
  class_def = class_node.body

  if !class_def
    []
  elsif class_def.begin_type?
    class_def.children
  else
    [class_def]
  end
end

#extend_call?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/static_class.rb', line 102

def extend_call?(node)
  node.send_type? && node.method?(:extend)
end

#on_class(class_node)

[ GitHub ]

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

def on_class(class_node)
  return if class_node.parent_class
  return unless class_convertible_to_module?(class_node)

  add_offense(class_node) do |corrector|
    autocorrect(corrector, class_node)
  end
end

#sclass_convertible_to_module?(node) ⇒ Boolean (private)

[ GitHub ]

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

def sclass_convertible_to_module?(node)
  return false unless node.sclass_type?

  class_elements(node).all? do |child|
    node_visibility(child) == :public && (child.def_type? || child.equals_asgn?)
  end
end