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Class: Module

Relationships & Source Files
Namespace Children
Modules:
Concerning
Exceptions:
DelegationError
Extension / Inclusion / Inheritance Descendants
Subclasses:
ActiveModel::SecurePassword::InstanceMethodsOnActivation, ActiveRecord::AttributeMethods::GeneratedAttributeMethods, ActiveRecord::Delegation::GeneratedRelationMethods, ActiveRecord::Enum::EnumMethods, ActiveSupport::Deprecation::DeprecatedConstantProxy, ActiveModel::Type::Helpers::AcceptsMultiparameterTime, ActiveModel::Validations::AcceptanceValidator::LazilyDefineAttributes
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, Concerning
Inherits: Object
Defined in: activesupport/lib/active_support/core_ext/module/attribute_accessors.rb,
activesupport/lib/active_support/core_ext/module/aliasing.rb,
activesupport/lib/active_support/core_ext/module/anonymous.rb,
activesupport/lib/active_support/core_ext/module/attr_internal.rb,
activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb,
activesupport/lib/active_support/core_ext/module/concerning.rb,
activesupport/lib/active_support/core_ext/module/delegation.rb,
activesupport/lib/active_support/core_ext/module/deprecation.rb,
activesupport/lib/active_support/core_ext/module/introspection.rb,
activesupport/lib/active_support/core_ext/module/redefine_method.rb,
activesupport/lib/active_support/core_ext/module/remove_method.rb,
activesupport/lib/active_support/core_ext/object/deep_dup.rb,
activesupport/lib/active_support/core_ext/object/json.rb

Overview

Attribute Accessors per Thread

Extends the module object with class/module and instance accessors for class/module attributes, just like the native attr* accessors for instance attributes, but does so on a per-thread basis.

So the values are scoped within the Thread.current space under the class name of the module.

Note that it can also be scoped per-fiber if Rails.application.config.active_support.isolation_level is set to :fiber.

Constant Summary

Class Attribute Summary

Instance Attribute Summary

Instance Method Summary

Concerning - Included

#concern

A low-cruft shortcut to define a concern.
#concerning

Define a new concern and mix it in.

Class Attribute Details

.attr_internal_naming_format (rw)

[ GitHub ] 

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 22



class << self; attr_accessor :attr_internal_naming_format end


  







Instance Attribute Details



  

    #anonymous?  ⇒ Boolean  (readonly)
  



  

    

A module may or may not have a name.



module M; end
M.name # => "M"

m = Module.new
m.name # => nil



anonymous? method returns true if module does not have a name, false otherwise:



Module.new.anonymous? # => true

module M; end
M.anonymous?          # => false



A module gets a name when it is first assigned to a constant. Either via the module or class keyword or by an explicit assignment:



m = Module.new # creates an anonymous module
m.anonymous?   # => true
M = m          # m gets a name here as a side-effect
m.name         # => "M"
m.anonymous?   # => false


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/anonymous.rb', line 27



def anonymous?
  name.nil?
end


  







Instance Method Details



  

    #alias_attribute(new_name, old_name)  
  



  

    

Allows you to make aliases for attributes, which includes getter, setter, and a predicate.



class Content < ActiveRecord::Base
  # has a title attribute
end

class Email < Content
  alias_attribute :subject, :title
end

e = Email.find(1)
e.title    # => "Superstars"
e.subject  # => "Superstars"
e.subject? # => true
e.subject = "Megastars"
e.title    # => "Megastars"


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/aliasing.rb', line 21



def alias_attribute(new_name, old_name)
  # The following reader methods use an explicit `self` receiver in order to
  # support aliases that start with an uppercase letter. Otherwise, they would
  # be resolved as constants instead.
  module_eval <<-STR, __FILE__, __LINE__ + 1
    def #{new_name}; self.#{old_name}; end          # def subject; self.title; end
    def #{new_name}?; self.#{old_name}?; end        # def subject?; self.title?; end
    def #{new_name}=(v); self.#{old_name} = v; end  # def subject=(v); self.title = v; end
  STR
end


  








  

    #as_json(options = nil)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/object/json.rb', line 53



def as_json(options = nil) # :nodoc:
  name
end


  








  

    #attr_internal(*attrs)  
  



  

    

Alias for #attr_internal_accessor.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 20



alias_method :attr_internal, :attr_internal_accessor


  








  

    #attr_internal_accessor(*attrs)  
    Also known as: #attr_internal
  



  

    

Declares an attribute reader and writer backed by an internally-named instance variable.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 16



def attr_internal_accessor(*attrs)
  attr_internal_reader(*attrs)
  attr_internal_writer(*attrs)
end


  








  

    #attr_internal_define(attr_name, type)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 30



def attr_internal_define(attr_name, type)
  internal_name = attr_internal_ivar_name(attr_name).delete_prefix("@")
  # use native attr_* methods as they are faster on some Ruby implementations
  public_send("attr_#{type}", internal_name)
  attr_name, internal_name = "#{attr_name}=", "#{internal_name}=" if type == :writer
  alias_method attr_name, internal_name
  remove_method internal_name
end


  








  

    #attr_internal_ivar_name(attr)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 26



def attr_internal_ivar_name(attr)
  Module.attr_internal_naming_format % attr
end


  








  

    #attr_internal_reader(*attrs)  
  



  

    

Declares an attribute reader backed by an internally-named instance variable.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 5



def attr_internal_reader(*attrs)
  attrs.each { |attr_name| attr_internal_define(attr_name, :reader) }
end


  








  

    #attr_internal_writer(*attrs)  
  



  

    

Declares an attribute writer backed by an internally-named instance variable.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 10



def attr_internal_writer(*attrs)
  attrs.each { |attr_name| attr_internal_define(attr_name, :writer) }
end


  








  

    #cattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil, &blk)  
  



  

    

Alias for #mattr_accessor.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 213



alias :cattr_accessor :mattr_accessor


  








  

    #cattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil, location: nil)  
  



  

    

Alias for #mattr_reader.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 75



alias :cattr_reader :mattr_reader


  








  

    #cattr_writer(*syms, instance_writer: true, instance_accessor: true, default: nil, location: nil)  
  



  

    

Alias for #mattr_writer.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 140



alias :cattr_writer :mattr_writer


  








  

    #deep_dup  
  



  

    

Returns a copy of module or class if it’s anonymous. If it’s named, returns self.



Object.deep_dup == Object # => true
klass = Class.new
klass.deep_dup == klass # => false


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/object/deep_dup.rb', line 64



def deep_dup
  if name.nil?
    super
  else
    self
  end
end


  








  

    #delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil)  
  



  

    

Provides a delegate class method to easily expose contained objects’ public methods as your own.



Options


  • 

    :to - Specifies the target object name as a symbol or string
    

  • 

    :prefix - Prefixes the new method with the target name or a custom prefix
    

  • 

    :allow_nil - If set to true, prevents a ::Module::DelegationError from being raised
    

  • 

    :private - If set to true, changes method visibility to private
    




The macro receives one or more method names (specified as symbols or strings) and the name of the target object via the :to option (also a symbol or string).



Delegation is particularly useful with Active Record associations:



class Greeter < ActiveRecord::Base
  def hello
    'hello'
  end

  def goodbye
    'goodbye'
  end
end

class Foo < ActiveRecord::Base
  belongs_to :greeter
  delegate :hello, to: :greeter
end

Foo.new.hello   # => "hello"
Foo.new.goodbye # => NoMethodError: undefined method `goodbye' for #<Foo:0x1af30c>



Multiple delegates to the same target are allowed:



class Foo < ActiveRecord::Base
  belongs_to :greeter
  delegate :hello, :goodbye, to: :greeter
end

Foo.new.goodbye # => "goodbye"



Methods can be delegated to instance variables, class variables, or constants by providing them as a symbols:



class Foo
  CONSTANT_ARRAY = [0,1,2,3]
  @@class_array  = [4,5,6,7]

  def initialize
    @instance_array = [8,9,10,11]
  end
  delegate :sum, to: :CONSTANT_ARRAY
  delegate :min, to: :@@class_array
  delegate :max, to: :@instance_array
end

Foo.new.sum # => 6
Foo.new.min # => 4
Foo.new.max # => 11



It’s also possible to delegate a method to the class by using :class:



class Foo
  def self.hello
    "world"
  end

  delegate :hello, to: :class
end

Foo.new.hello # => "world"



Delegates can optionally be prefixed using the :prefix option. If the value is true, the delegate methods are prefixed with the name of the object being delegated to.



Person = Struct.new(:name, :address)

class Invoice < Struct.new(:client)
  delegate :name, :address, to: :client, prefix: true
end

john_doe = Person.new('John Doe', 'Vimmersvej 13')
invoice = Invoice.new(john_doe)
invoice.client_name    # => "John Doe"
invoice.client_address # => "Vimmersvej 13"



It is also possible to supply a custom prefix.



class Invoice < Struct.new(:client)
  delegate :name, :address, to: :client, prefix: :customer
end

invoice = Invoice.new(john_doe)
invoice.customer_name    # => 'John Doe'
invoice.customer_address # => 'Vimmersvej 13'



The delegated methods are public by default. Pass private: true to change that.



class User < ActiveRecord::Base
  has_one :profile
  delegate :first_name, to: :profile
  delegate :date_of_birth, to: :profile, private: true

  def age
    Date.today.year - date_of_birth.year
  end
end

User.new.first_name # => "Tomas"
User.new.date_of_birth # => NoMethodError: private method `date_of_birth' called for #<User:0x00000008221340>
User.new.age # => 2



If the target is nil and does not respond to the delegated method a ::Module::DelegationError is raised. If you wish to instead return nil, use the :allow_nil option.



class User < ActiveRecord::Base
  has_one :profile
  delegate :age, to: :profile
end

User.new.age
# => Module::DelegationError: User#age delegated to profile.age, but profile is nil



But if not having a profile yet is fine and should not be an error condition:



class User < ActiveRecord::Base
  has_one :profile
  delegate :age, to: :profile, allow_nil: true
end

User.new.age # nil



Note that if the target is not nil then the call is attempted regardless of the :allow_nil option, and thus an exception is still raised if said object does not respond to the method:



class Foo
  def initialize(bar)
    @bar = bar
  end

  delegate :name, to: :@bar, allow_nil: true
end

Foo.new("Bar").name # raises NoMethodError: undefined method `name'



The target method must be public, otherwise it will raise NoMethodError.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/delegation.rb', line 171



def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil)
  unless to
    raise ArgumentError, "Delegation needs a target. Supply a keyword argument 'to' (e.g. delegate :hello, to: :greeter)."
  end

  if prefix == true && /^[^a-z_]/.match?(to)
    raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method."
  end

  method_prefix = \
    if prefix
      "#{prefix == true ? to : prefix}_"
    else
      ""
    end

  location = caller_locations(1, 1).first
  file, line = location.path, location.lineno

  receiver = to.to_s
  receiver = "self.#{receiver}" if DELEGATION_RESERVED_METHOD_NAMES.include?(receiver)

  method_def = []
  method_names = []

  method_def << "self.private" if private

  methods.each do |method|
    method_name = prefix ? "#{method_prefix}#{method}" : method
    method_names << method_name.to_sym

    # Attribute writer methods only accept one argument. Makes sure []=
    # methods still accept two arguments.
    definition = \
      if /[^\]]=\z/.match?(method)
        "arg"
      else
        method_object =
          begin
            if to.is_a?(Module)
              to.method(method)
            elsif receiver == "self.class"
              method(method)
            end
          rescue NameError
            # Do nothing. Fall back to `"..."`
          end

        if method_object
          parameters = method_object.parameters

          if (parameters.map(&:first) & [:opt, :rest, :keyreq, :key, :keyrest]).any?
            "..."
          else
            defn = parameters.filter_map { |type, arg| arg if type == :req }
            defn << "&block"
            defn.join(", ")
          end
        else
          "..."
        end
      end

    # The following generated method calls the target exactly once, storing
    # the returned value in a dummy variable.
    #
    # Reason is twofold: On one hand doing less calls is in general better.
    # On the other hand it could be that the target has side-effects,
    # whereas conceptually, from the user point of view, the delegator should
    # be doing one call.
    if allow_nil
      method = method.to_s

      method_def <<
        "def #{method_name}(#{definition})" <<
        "  _ = #{receiver}" <<
        "  if !_.nil? || nil.respond_to?(:#{method})" <<
        "    _.#{method}(#{definition})" <<
        "  end" <<
        "end"
    else
      method = method.to_s
      method_name = method_name.to_s

      method_def <<
        "def #{method_name}(#{definition})" <<
        "  _ = #{receiver}" <<
        "  _.#{method}(#{definition})" <<
        "rescue NoMethodError => e" <<
        "  if _.nil? && e.name == :#{method}" <<
        %(   raise DelegationError, "#{self}##{method_name} delegated to #{receiver}.#{method}, but #{receiver} is nil: \#{self.inspect}") <<
        "  else" <<
        "    raise" <<
        "  end" <<
        "end"
    end
  end
  module_eval(method_def.join(";"), file, line)
  method_names
end


  








  

    #delegate_missing_to(target, allow_nil: nil)  
  



  

    

When building decorators, a common pattern may emerge:



class Partition
  def initialize(event)
    @event = event
  end

  def person
    detail.person || creator
  end

  private
    def respond_to_missing?(name, include_private = false)
      @event.respond_to?(name, include_private)
    end

    def method_missing(method, *args, &block)
      @event.send(method, *args, &block)
    end
end



With delegate_missing_to, the above is condensed to:



class Partition
  delegate_missing_to :@event

  def initialize(event)
    @event = event
  end

  def person
    detail.person || creator
  end
end



The target can be anything callable within the object, e.g. instance variables, methods, constants, etc.



The delegated method must be public on the target, otherwise it will raise ::Module::DelegationError. If you wish to instead return nil, use the :allow_nil option.



The marshal_dump and _dump methods are exempt from delegation due to possible interference when calling Marshal.dump(object), should the delegation target method of object add or remove instance variables.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/delegation.rb', line 318



def delegate_missing_to(target, allow_nil: nil)
  target = target.to_s
  target = "self.#{target}" if DELEGATION_RESERVED_METHOD_NAMES.include?(target)

  module_eval <<-RUBY, __FILE__, __LINE__ + 1
    def respond_to_missing?(name, include_private = false)
      # It may look like an oversight, but we deliberately do not pass
      # include_private, because they do not get delegated.

      return false if name == :marshal_dump || name == :_dump
      #{target}.respond_to?(name) || super
    end

    def method_missing(method, *args, &block)
      if #{target}.respond_to?(method)
        #{target}.public_send(method, *args, &block)
      else
        begin
          super
        rescue NoMethodError
          if #{target}.nil?
            if #{allow_nil == true}
              nil
            else
              raise DelegationError, "\#{method} delegated to #{target}, but #{target} is nil"
            end
          else
            raise
          end
        end
      end
    end
    ruby2_keywords(:method_missing)
  RUBY
end


  








  

    #deprecate(*method_names, deprecator: nil, **options)  
  



  

    

deprecate :foo, deprecator: MyLib.deprecator



deprecate :foo, bar: "warning!", deprecator: MyLib.deprecator



A deprecator is typically an instance of ::ActiveSupport::Deprecation, but you can also pass any object that responds to deprecation_warning(deprecated_method_name, message, caller_backtrace) where you can implement your custom warning behavior.



class MyLib::Deprecator
  def deprecation_warning(deprecated_method_name, message, caller_backtrace = nil)
    message = "#{deprecated_method_name} is deprecated and will be removed from MyLibrary | #{message}"
    Kernel.warn message
  end
end


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/deprecation.rb', line 17



def deprecate(*method_names, deprecator: nil, **options)
  if deprecator.is_a?(ActiveSupport::Deprecation)
    deprecator.deprecate_methods(self, *method_names, **options)
  elsif deprecator
    # we just need any instance to call deprecate_methods, but the deprecation will be emitted by deprecator
    ActiveSupport.deprecator.deprecate_methods(self, *method_names, **options, deprecator: deprecator)
  else
    ActiveSupport.deprecator.warn("Module.deprecate without a deprecator is deprecated")
    ActiveSupport::Deprecation._instance.deprecate_methods(self, *method_names, **options)
  end
end


  








  

    #mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil, &blk)  
    Also known as: #cattr_accessor
  



  

    

Defines both class and instance accessors for class attributes. All class and instance methods created will be public, even if this method is called with a private or protected access modifier.



module HairColors
  mattr_accessor :hair_colors
end

class Person
  include HairColors
end

HairColors.hair_colors = [:brown, :black, :blonde, :red]
HairColors.hair_colors # => [:brown, :black, :blonde, :red]
Person.new.hair_colors # => [:brown, :black, :blonde, :red]



If a subclass changes the value then that would also change the value for parent class. Similarly if parent class changes the value then that would change the value of subclasses too.



class Citizen < Person
end

Citizen.new.hair_colors << :blue
Person.new.hair_colors # => [:brown, :black, :blonde, :red, :blue]



To omit the instance writer method, pass instance_writer: false. To omit the instance reader method, pass instance_reader: false.



module HairColors
  mattr_accessor :hair_colors, instance_writer: false, instance_reader: false
end

class Person
  include HairColors
end

Person.new.hair_colors = [:brown]  # => NoMethodError
Person.new.hair_colors             # => NoMethodError



Or pass instance_accessor: false, to omit both instance methods.



module HairColors
  mattr_accessor :hair_colors, instance_accessor: false
end

class Person
  include HairColors
end

Person.new.hair_colors = [:brown]  # => NoMethodError
Person.new.hair_colors             # => NoMethodError



You can set a default value for the attribute.



module HairColors
  mattr_accessor :hair_colors, default: [:brown, :black, :blonde, :red]
  mattr_accessor(:hair_styles) { [:long, :short] }
end

class Person
  include HairColors
end

Person.class_variable_get("@@hair_colors") # => [:brown, :black, :blonde, :red]
Person.class_variable_get("@@hair_styles") # => [:long, :short]


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 208



def mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil, &blk)
  location = caller_locations(1, 1).first
  mattr_reader(*syms, instance_reader: instance_reader, instance_accessor: instance_accessor, default: default, location: location, &blk)
  mattr_writer(*syms, instance_writer: instance_writer, instance_accessor: instance_accessor, default: default, location: location)
end


  








  

    #mattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil, location: nil)  
    Also known as: #cattr_reader
  



  

    

Defines a class attribute and creates a class and instance reader methods. The underlying class variable is set to nil, if it is not previously defined. All class and instance methods created will be public, even if this method is called with a private or protected access modifier.



module HairColors
  mattr_reader :hair_colors
end

HairColors.hair_colors # => nil
HairColors.class_variable_set("@@hair_colors", [:brown, :black])
HairColors.hair_colors # => [:brown, :black]



The attribute name must be a valid method name in Ruby.



module Foo
  mattr_reader :"1_Badname"
end
# => NameError: invalid attribute name: 1_Badname



To omit the instance reader method, pass instance_reader: false or instance_accessor: false.



module HairColors
  mattr_reader :hair_colors, instance_reader: false
end

class Person
  include HairColors
end

Person.new.hair_colors # => NoMethodError



You can set a default value for the attribute.



module HairColors
  mattr_reader :hair_colors, default: [:brown, :black, :blonde, :red]
  mattr_reader(:hair_styles) { [:long, :short] }
end

class Person
  include HairColors
end

Person.new.hair_colors # => [:brown, :black, :blonde, :red]
Person.new.hair_styles # => [:long, :short]


  





  
Raises:


    
  
  • 
    (TypeError)
  
    • 





  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 55



def mattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil, location: nil)
  raise TypeError, "module attributes should be defined directly on class, not singleton" if singleton_class?
  location ||= caller_locations(1, 1).first

  definition = []
  syms.each do |sym|
    raise NameError.new("invalid attribute name: #{sym}") unless /\A[_A-Za-z]\w*\z/.match?(sym)

    definition << "def self.#{sym}; @@#{sym}; end"

    if instance_reader && instance_accessor
      definition << "def #{sym}; @@#{sym}; end"
    end

    sym_default_value = (block_given? && default.nil?) ? yield : default
    class_variable_set("@@#{sym}", sym_default_value) unless sym_default_value.nil? && class_variable_defined?("@@#{sym}")
  end

  module_eval(definition.join(";"), location.path, location.lineno)
end


  








  

    #mattr_writer(*syms, instance_writer: true, instance_accessor: true, default: nil, location: nil)  
    Also known as: #cattr_writer
  



  

    

Defines a class attribute and creates a class and instance writer methods to allow assignment to the attribute. All class and instance methods created will be public, even if this method is called with a private or protected access modifier.



module HairColors
  mattr_writer :hair_colors
end

class Person
  include HairColors
end

HairColors.hair_colors = [:brown, :black]
Person.class_variable_get("@@hair_colors") # => [:brown, :black]
Person.new.hair_colors = [:blonde, :red]
HairColors.class_variable_get("@@hair_colors") # => [:blonde, :red]



To omit the instance writer method, pass instance_writer: false or instance_accessor: false.



module HairColors
  mattr_writer :hair_colors, instance_writer: false
end

class Person
  include HairColors
end

Person.new.hair_colors = [:blonde, :red] # => NoMethodError



You can set a default value for the attribute.



module HairColors
  mattr_writer :hair_colors, default: [:brown, :black, :blonde, :red]
  mattr_writer(:hair_styles) { [:long, :short] }
end

class Person
  include HairColors
end

Person.class_variable_get("@@hair_colors") # => [:brown, :black, :blonde, :red]
Person.class_variable_get("@@hair_styles") # => [:long, :short]


  





  
Raises:


    
  
  • 
    (TypeError)
  
    • 





  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 121



def mattr_writer(*syms, instance_writer: true, instance_accessor: true, default: nil, location: nil)
  raise TypeError, "module attributes should be defined directly on class, not singleton" if singleton_class?
  location ||= caller_locations(1, 1).first

  definition = []
  syms.each do |sym|
    raise NameError.new("invalid attribute name: #{sym}") unless /\A[_A-Za-z]\w*\z/.match?(sym)
    definition << "def self.#{sym}=(val); @@#{sym} = val; end"

    if instance_writer && instance_accessor
      definition << "def #{sym}=(val); @@#{sym} = val; end"
    end

    sym_default_value = (block_given? && default.nil?) ? yield : default
    class_variable_set("@@#{sym}", sym_default_value) unless sym_default_value.nil? && class_variable_defined?("@@#{sym}")
  end

  module_eval(definition.join(";"), location.path, location.lineno)
end


  








  

    #method_visibility(method)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/redefine_method.rb', line 30



def method_visibility(method) # :nodoc:
  case
  when private_method_defined?(method)
    :private
  when protected_method_defined?(method)
    :protected
  else
    :public
  end
end


  








  

    #module_parent  
  



  

    

Returns the module which contains this one according to its name.



module M
  module N
  end
end
X = M::N

M::N.module_parent # => M
X.module_parent    # => M



The parent of top-level and anonymous modules is ::Object.



M.module_parent          # => Object
Module.new.module_parent # => Object


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/introspection.rb', line 34



def module_parent
  module_parent_name ? ActiveSupport::Inflector.constantize(module_parent_name) : Object
end


  








  

    #module_parent_name  
  



  

    

Returns the name of the module containing this one.



M::N.module_parent_name # => "M"


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/introspection.rb', line 9



def module_parent_name
  if defined?(@parent_name)
    @parent_name
  else
    parent_name = name =~ /::[^:]+\z/ ? -$` : nil
    @parent_name = parent_name unless frozen?
    parent_name
  end
end


  








  

    #module_parents  
  



  

    

Returns all the parents of this module according to its name, ordered from nested outwards. The receiver is not contained within the result.



module M
  module N
  end
end
X = M::N

M.module_parents    # => [Object]
M::N.module_parents # => [M, Object]
X.module_parents    # => [M, Object]


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/introspection.rb', line 50



def module_parents
  parents = []
  if module_parent_name
    parts = module_parent_name.split("::")
    until parts.empty?
      parents << ActiveSupport::Inflector.constantize(parts * "::")
      parts.pop
    end
  end
  parents << Object unless parents.include? Object
  parents
end


  








  

    #redefine_method(method, &block)  
  



  

    

Replaces the existing method definition, if there is one, with the passed block as its body.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/redefine_method.rb', line 17



def redefine_method(method, &block)
  visibility = method_visibility(method)
  silence_redefinition_of_method(method)
  define_method(method, &block)
  send(visibility, method)
end


  








  

    #redefine_singleton_method(method, &block)  
  



  

    

Replaces the existing singleton method definition, if there is one, with the passed block as its body.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/redefine_method.rb', line 26



def redefine_singleton_method(method, &block)
  singleton_class.redefine_method(method, &block)
end


  








  

    #remove_possible_method(method)  
  



  

    

Removes the named method, if it exists.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/remove_method.rb', line 7



def remove_possible_method(method)
  if method_defined?(method) || private_method_defined?(method)
    undef_method(method)
  end
end


  








  

    #remove_possible_singleton_method(method)  
  



  

    

Removes the named singleton method, if it exists.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/remove_method.rb', line 14



def remove_possible_singleton_method(method)
  singleton_class.remove_possible_method(method)
end


  








  

    #silence_redefinition_of_method(method)  
  



  

    

Marks the named method as intended to be redefined, if it exists. Suppresses the Ruby method redefinition warning. Prefer #redefine_method where possible.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/redefine_method.rb', line 7



def silence_redefinition_of_method(method)
  if method_defined?(method) || private_method_defined?(method)
    # This suppresses the "method redefined" warning; the self-alias
    # looks odd, but means we don't need to generate a unique name
    alias_method method, method
  end
end


  








  

    #thread_cattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil)  
  



  

    

Alias for #thread_mattr_accessor.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 174



alias :thread_cattr_accessor :thread_mattr_accessor


  








  

    #thread_cattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil)  
  



  

    

Alias for #thread_mattr_reader.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 81



alias :thread_cattr_reader :thread_mattr_reader


  








  

    #thread_cattr_writer(*syms, instance_writer: true, instance_accessor: true)  
  



  

    

Alias for #thread_mattr_writer.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 123



alias :thread_cattr_writer :thread_mattr_writer


  








  

    #thread_mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil)  
    Also known as: #thread_cattr_accessor
  



  

    

Defines both class and instance accessors for class attributes.



class Account
  thread_mattr_accessor :user
end

Account.user = "DHH"
Account.user     # => "DHH"
Account.new.user # => "DHH"



Unlike #mattr_accessor, values are not shared with subclasses or parent classes. If a subclass changes the value, the parent class’ value is not changed. If the parent class changes the value, the value of subclasses is not changed.



class Customer < Account
end

Account.user   # => "DHH"
Customer.user  # => nil
Customer.user  = "Rafael"
Customer.user  # => "Rafael"
Account.user   # => "DHH"



To omit the instance writer method, pass instance_writer: false. To omit the instance reader method, pass instance_reader: false.



class Current
  thread_mattr_accessor :user, instance_writer: false, instance_reader: false
end

Current.new.user = "DHH"  # => NoMethodError
Current.new.user          # => NoMethodError



Or pass instance_accessor: false, to omit both instance methods.



class Current
  thread_mattr_accessor :user, instance_accessor: false
end

Current.new.user = "DHH"  # => NoMethodError
Current.new.user          # => NoMethodError



A default value may be specified using the :default option. Because multiple threads can access the default value, non-frozen default values will be duped and frozen.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 170



def thread_mattr_accessor(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil)
  thread_mattr_reader(*syms, instance_reader: instance_reader, instance_accessor: instance_accessor, default: default)
  thread_mattr_writer(*syms, instance_writer: instance_writer, instance_accessor: instance_accessor)
end


  








  

    #thread_mattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil)  
    Also known as: #thread_cattr_reader
  

  

    This method is for internal use only.
  



  

    

Defines a per-thread class attribute and creates class and instance reader methods. The underlying per-thread class variable is set to nil, if it is not previously defined.



module Current
  thread_mattr_reader :user
end

Current.user = "DHH"
Current.user # => "DHH"
Thread.new { Current.user }.value # => nil



The attribute name must be a valid method name in Ruby.



module Foo
  thread_mattr_reader :"1_Badname"
end
# => NameError: invalid attribute name: 1_Badname



To omit the instance reader method, pass instance_reader: false or instance_accessor: false.



class Current
  thread_mattr_reader :user, instance_reader: false
end

Current.new.user # => NoMethodError


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 41



def thread_mattr_reader(*syms, instance_reader: true, instance_accessor: true, default: nil) # :nodoc:
  syms.each do |sym|
    raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym)

    # The following generated method concatenates `object_id` because we want
    # subclasses to maintain independent values.
    if default.nil?
      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def self.#{sym}
          @__thread_mattr_#{sym} ||= "attr_#{sym}_\#{object_id}"
          ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}]
        end
      EOS
    else
      default = default.dup.freeze unless default.frozen?
      singleton_class.define_method("#{sym}_default_value") { default }

      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def self.#{sym}
          @__thread_mattr_#{sym} ||= "attr_#{sym}_\#{object_id}"
          value = ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}]

          if value.nil? && !::ActiveSupport::IsolatedExecutionState.key?(@__thread_mattr_#{sym})
            ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}] = #{sym}_default_value
          else
            value
          end
        end
      EOS
    end

    if instance_reader && instance_accessor
      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def #{sym}
          self.class.#{sym}
        end
      EOS
    end
  end
end


  








  

    #thread_mattr_writer(*syms, instance_writer: true, instance_accessor: true)  
    Also known as: #thread_cattr_writer
  

  

    This method is for internal use only.
  



  

    

Defines a per-thread class attribute and creates a class and instance writer methods to allow assignment to the attribute.



module Current
  thread_mattr_writer :user
end

Current.user = "DHH"
Thread.current[:attr_Current_user] # => "DHH"



To omit the instance writer method, pass instance_writer: false or instance_accessor: false.



class Current
  thread_mattr_writer :user, instance_writer: false
end

Current.new.user = "DHH" # => NoMethodError


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb', line 101



def thread_mattr_writer(*syms, instance_writer: true, instance_accessor: true) # :nodoc:
  syms.each do |sym|
    raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym)

    # The following generated method concatenates `object_id` because we want
    # subclasses to maintain independent values.
    class_eval(<<-EOS, __FILE__, __LINE__ + 1)
      def self.#{sym}=(obj)
        @__thread_mattr_#{sym} ||= "attr_#{sym}_\#{object_id}"
        ::ActiveSupport::IsolatedExecutionState[@__thread_mattr_#{sym}] = obj
      end
    EOS

    if instance_writer && instance_accessor
      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def #{sym}=(obj)
          self.class.#{sym} = obj
        end
      EOS
    end
  end
end