Various extensions for the Ruby core Module class.

Methods
A
L
M
P
Instance Public methods
alias_attribute(new_name, old_name)

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"
# File activesupport/lib/active_support/core_ext/module/aliasing.rb, line 65
      def alias_attribute(new_name, old_name)
        module_eval "          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
", __FILE__, __LINE__ + 1
      end
alias_method_chain(target, feature)

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.

# File activesupport/lib/active_support/core_ext/module/aliasing.rb, line 25
def alias_method_chain(target, feature)
  # Strip out punctuation on predicates or bang methods since
  # e.g. target?_without_feature is not a valid method name.
  aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
  yield(aliased_target, punctuation) if block_given?
  with_method, without_method = "#{aliased_target}_with_#{feature}#{punctuation}", "#{aliased_target}_without_#{feature}#{punctuation}"
  alias_method without_method, target
  alias_method target, with_method
  case
    when public_method_defined?(without_method)
      public target
    when protected_method_defined?(without_method)
      protected target
    when private_method_defined?(without_method)
      private target
  end
end
local_constant_names()

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

# File activesupport/lib/active_support/core_ext/module/introspection.rb, line 85
def local_constant_names
  local_constants.map { |c| c.to_s }
end
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.

# File activesupport/lib/active_support/core_ext/module/introspection.rb, line 65
def local_constants
  inherited = {}
  ancestors.each do |anc|
    next if anc == self
    anc.constants.each { |const| inherited[const] = anc.const_get(const) }
  end
  constants.select do |const|
    !inherited.key?(const) || inherited[const].object_id != const_get(const).object_id
  end
end
model_name()

Returns an ActiveSupport::ModelName object for module. It can be used to retrieve all kinds of naming-related information.

# File activesupport/lib/active_support/core_ext/module/model_naming.rb, line 20
def model_name
  @model_name ||= ::ActiveSupport::ModelName.new(name)
end
parent()

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

module M
  module N
  end
end
X = M::N
p M::N.parent # => M
p X.parent    # => M

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

p M.parent          # => Object
p Module.new.parent # => Object
# File activesupport/lib/active_support/core_ext/module/introspection.rb, line 30
def parent
  parent_name ? parent_name.constantize : Object
end
parent_name()

Returns the name of the module containing this one.

p M::N.parent_name # => "M"
# File activesupport/lib/active_support/core_ext/module/introspection.rb, line 7
def parent_name
  unless defined? @parent_name
    @parent_name = name =~ /::[^:]+\Z/ ? $`.freeze : nil
  end
  @parent_name
end
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
p M.parents    # => [Object]
p M::N.parents # => [M, Object]
p X.parents    # => [M, Object]
# File activesupport/lib/active_support/core_ext/module/introspection.rb, line 47
def parents
  parents = []
  if parent_name
    parts = parent_name.split('::')
    until parts.empty?
      parents << (parts * '::').constantize
      parts.pop
    end
  end
  parents << Object unless parents.include? Object
  parents
end