Module

Returns String#underscore applied to the module name minus trailing classes.

  ActiveRecord.as_load_path               # => "active_record"
  ActiveRecord::Associations.as_load_path # => "active_record/associations"
  ActiveRecord::Base.as_load_path         # => "active_record" (Base is a class)

The Kernel module gives an empty string by definition.

  Kernel.as_load_path # => ""
  Math.as_load_path   # => "math"

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

  some_person.age
  => 25
  some_person.age = 26
  some_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 }

Alias for attr_internal_accessor

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 as the final :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 object to which you delegate can be nil, you may want to use the :allow_nil option. In that case, it returns nil instead of raising a NoMethodError exception:

 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

Returns the classes in the current ObjectSpace where this module has been mixed in according to Module#included_modules.

  module M
  end

  module N
    include M
  end

  class C
    include M
  end

  class D < C
  end

  p M.included_in_classes # => [C, D]

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