Class Module
In: lib/active_support/core_ext/object/duplicable.rb
lib/active_support/core_ext/module/remove_method.rb
lib/active_support/core_ext/module/attr_internal.rb
lib/active_support/core_ext/module/delegation.rb
lib/active_support/core_ext/module/aliasing.rb
lib/active_support/core_ext/module/anonymous.rb
lib/active_support/core_ext/module/attribute_accessors.rb
lib/active_support/core_ext/module/synchronization.rb
lib/active_support/core_ext/module/introspection.rb
lib/active_support/core_ext/module/attr_accessor_with_default.rb
lib/active_support/core_ext/module/reachable.rb
lib/active_support/core_ext/module/deprecation.rb
lib/active_support/core_ext/module/method_names.rb
Parent: Object

Methods

Attributes

attr_internal_naming_format  [RW] 

Public Instance methods

Allows you to make aliases for attributes, which includes getter, setter, and query methods.

Example:

  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"

Encapsulates the common pattern of:

  alias_method :foo_without_feature, :foo
  alias_method :foo, :foo_with_feature

With this, you simply do:

  alias_method_chain :foo, :feature

And both aliases are set up for you.

Query and bang methods (foo?, foo!) keep the same punctuation:

  alias_method_chain :foo?, :feature

is equivalent to

  alias_method :foo_without_feature?, :foo?
  alias_method :foo?, :foo_with_feature?

so you can safely chain foo, foo?, and foo! with the same feature.

A module may or may not have a name.

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

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

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 = m          # => m gets a name here as a side-effect
  m.name         # => "M"

Declare an attribute accessor with an initial default return value.

To give attribute :age the initial value 25:

  class Person
    attr_accessor_with_default :age, 25
  end

  person = Person.new
  person.age # => 25

  person.age = 26
  person.age # => 26

To give attribute :element_name a dynamic default value, evaluated in scope of self:

  attr_accessor_with_default(:element_name) { name.underscore }
attr_internal(*attrs)

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

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

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

Provides a delegate class method to easily expose contained objects’ methods as your own. Pass one or more methods (specified as symbols or strings) and the name of the target object via the :to option (also a symbol or string). At least one method and the :to option are required.

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

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"

If the delegate object is nil an exception is raised, and that happens no matter whether nil responds to the delegated method. You can get a nil instead with the +:allow_nil+ option.

 class Foo
   attr_accessor :bar
   def initialize(bar = nil)
     @bar = bar
   end
   delegate :zoo, :to => :bar
 end

 Foo.new.zoo   # raises NoMethodError exception (you called nil.zoo)

 class Foo
   attr_accessor :bar
   def initialize(bar = nil)
     @bar = bar
   end
   delegate :zoo, :to => :bar, :allow_nil => true
 end

 Foo.new.zoo   # returns nil

Declare that a method has been deprecated.

  deprecate :foo
  deprecate :bar => 'message'
  deprecate :foo, :bar, :baz => 'warning!', :qux => 'gone!'

Modules are not duplicable:

 m = Module.new # => #<Module:0x10328b6e0>
 m.dup          # => #<Module:0x10328b6e0>

Note dup returned the same module object.

Returns the names of the constants defined locally rather than the constants themselves. See local_constants.

Returns the constants that have been defined locally by this object and not in an ancestor. This method is exact if running under Ruby 1.9. In previous versions it may miss some constants if their definition in some ancestor is identical to their definition in the receiver.

Extends the module object with module and instance accessors for class attributes, just like the native attr* accessors for instance attributes.

 module AppConfiguration
   mattr_accessor :google_api_key
   self.google_api_key = "123456789"

   mattr_accessor :paypal_url
   self.paypal_url = "www.sandbox.paypal.com"
 end

 AppConfiguration.google_api_key = "overriding the api key!"

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

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

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

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

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

Returns the name of the module containing this one.

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

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

Synchronize access around a method, delegating synchronization to a particular mutex. A mutex (either a Mutex, or any object that responds to synchronize and yields to a block) must be provided as a final :with option. The :with option should be a symbol or string, and can represent a method, constant, or instance or class variable. Example:

  class SharedCache
    @@lock = Mutex.new
    def expire
      ...
    end
    synchronize :expire, :with => :@@lock
  end

[Validate]