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Class: RuboCop::Cop::Style::ModuleFunction

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/module_function.rb

Overview

Checks for use of extend self or module_function in a module.

Supported styles are: module_function (default), extend_self and forbidden.

A couple of things to keep in mind:

  • forbidden style prohibits the usage of both styles

  • in default mode (module_function), the cop won’t be activated when the module contains any private methods

Examples:

EnforcedStyle: module_function (default)

# bad
module Test
  extend self
  # ...
end

# good
module Test
  module_function
  # ...
end

# good
module Test
  extend self
  # ...
  private
  # ...
end

# good
module Test
  class << self
    # ...
  end
end

EnforcedStyle: extend_self

# bad
module Test
  module_function
  # ...
end

# good
module Test
  extend self
  # ...
end

# good
module Test
  class << self
    # ...
  end
end

EnforcedStyle: forbidden

# bad
module Test
  module_function
  # ...
end

# bad
module Test
  extend self
  # ...
end

# bad
module Test
  extend self
  # ...
  private
  # ...
end

# good
module Test
  class << self
    # ...
  end
end

Cop Safety Information:

  • Autocorrection is unsafe (and is disabled by default) because extend self and module_function do not behave exactly the same.

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

::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::ConfigurableEnforcedStyle - Included

::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

#check_extend_self(nodes) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 149

def check_extend_self(nodes)
  nodes.each do |node|
    yield node if module_function_node?(node)
  end
end

#check_forbidden(nodes) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 155

def check_forbidden(nodes)
  nodes.each do |node|
    yield node if extend_self_node?(node)
    yield node if module_function_node?(node)
  end
end

#check_module_function(nodes) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 141

def check_module_function(nodes)
  return if nodes.any? { |node| private_directive?(node) }

  nodes.each do |node|
    yield node if extend_self_node?(node)
  end
end

#each_wrong_style(nodes, &block) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 130

def each_wrong_style(nodes, &block)
  case style
  when :module_function
    check_module_function(nodes, &block)
  when :extend_self
    check_extend_self(nodes, &block)
  when :forbidden
    check_forbidden(nodes, &block)
  end
end

#extend_self_node?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 107

def_node_matcher :extend_self_node?, '(send nil? :extend self)'

#message(_range) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 162

def message(_range)
  return FORBIDDEN_MSG if style == :forbidden

  style == :module_function ? MODULE_FUNCTION_MSG : EXTEND_SELF_MSG
end

#module_function_node?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 104

def_node_matcher :module_function_node?, '(send nil? :module_function)'

#on_module(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 112

def on_module(node)
  return unless node.body&.begin_type?

  each_wrong_style(node.body.children) do |child_node|
    add_offense(child_node) do |corrector|
      next if style == :forbidden

      if extend_self_node?(child_node)
        corrector.replace(child_node, 'module_function')
      else
        corrector.replace(child_node, 'extend self')
      end
    end
  end
end

#private_directive?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/module_function.rb', line 110

def_node_matcher :private_directive?, '(send nil? :private ...)'