Module: ActiveSupport::CoreExtensions::Module

Included in:
Module
Defined in:
activesupport/lib/active_support/core_ext/module.rb,
activesupport/lib/active_support/core_ext/module/aliasing.rb,
activesupport/lib/active_support/core_ext/module/model_naming.rb,
activesupport/lib/active_support/core_ext/module/introspection.rb

Overview

Various extensions for the Ruby core Module class.

Instance Method Summary collapse

Instance Method Details

#alias_attribute(new_name, old_name) ⇒ Object

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"


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# File 'activesupport/lib/active_support/core_ext/module/aliasing.rb', line 65

def alias_attribute(new_name, old_name)
  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

#alias_method_chain(target, feature) {|aliased_target, punctuation| ... } ⇒ Object

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.

Yields:

  • (aliased_target, punctuation)


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# 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_namesObject

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



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# 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_constantsObject

:nodoc:



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# File 'activesupport/lib/active_support/core_ext/module/introspection.rb', line 78

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_nameObject

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



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

def model_name
  @model_name ||= ::ActiveSupport::ModelName.new(name)
end

#parentObject

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


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

def parent
  parent_name ? parent_name.constantize : Object
end

#parent_nameObject

Returns the name of the module containing this one.

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


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# 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

#parentsObject

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]


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# 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