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Module

Extends the API for constants to be able to deal with qualified names. Arguments are assumed to be relative to the receiver.

Attributes

attr_internal_naming_format[RW]

Public Instance Methods

alias_attribute(new_name, old_name) click to toggle source

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 lib/active_support/core_ext/module/aliasing.rb, line 63
63:   def alias_attribute(new_name, old_name)
64:     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
65:   end
alias_method_chain(target, feature) click to toggle source

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 lib/active_support/core_ext/module/aliasing.rb, line 23
23:   def alias_method_chain(target, feature)
24:     # Strip out punctuation on predicates or bang methods since
25:     # e.g. target?_without_feature is not a valid method name.
26:     aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
27:     yield(aliased_target, punctuation) if block_given?
28: 
29:     with_method, without_method = "#{aliased_target}_with_#{feature}#{punctuation}", "#{aliased_target}_without_#{feature}#{punctuation}"
30: 
31:     alias_method without_method, target
32:     alias_method target, with_method
33: 
34:     case
35:       when public_method_defined?(without_method)
36:         public target
37:       when protected_method_defined?(without_method)
38:         protected target
39:       when private_method_defined?(without_method)
40:         private target
41:     end
42:   end
anonymous?() click to toggle source

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"
    # File lib/active_support/core_ext/module/anonymous.rb, line 19
19:   def anonymous?
20:     # Uses blank? because the name of an anonymous class is an empty
21:     # string in 1.8, and nil in 1.9.
22:     name.blank?
23:   end
attr_internal(*attrs) click to toggle source
attr_internal_accessor(*attrs) click to toggle source

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

    # File lib/active_support/core_ext/module/attr_internal.rb, line 14
14:   def attr_internal_accessor(*attrs)
15:     attr_internal_reader(*attrs)
16:     attr_internal_writer(*attrs)
17:   end
Also aliased as: attr_internal
attr_internal_reader(*attrs) click to toggle source

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

   # File lib/active_support/core_ext/module/attr_internal.rb, line 3
3:   def attr_internal_reader(*attrs)
4:     attrs.each {|attr_name| attr_internal_define(attr_name, :reader)}
5:   end
attr_internal_writer(*attrs) click to toggle source

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

    # File lib/active_support/core_ext/module/attr_internal.rb, line 8
 8:   def attr_internal_writer(*attrs)
 9:     attrs.each {|attr_name| attr_internal_define(attr_name, :writer)}
10:   end
delegate(*methods) click to toggle source

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
     # File lib/active_support/core_ext/module/delegation.rb, line 104
104:   def delegate(*methods)
105:     options = methods.pop
106:     unless options.is_a?(Hash) && to = options[:to]
107:       raise ArgumentError, "Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, :to => :greeter)."
108:     end
109:     prefix, to, allow_nil = options[:prefix], options[:to], options[:allow_nil]
110: 
111:     if prefix == true && to.to_s =~ /^[^a-z_]/
112:       raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method."
113:     end
114: 
115:     method_prefix =
116:       if prefix
117:         "#{prefix == true ? to : prefix}_"
118:       else
119:         ''
120:       end
121: 
122:     file, line = caller.first.split(':', 2)
123:     line = line.to_i
124: 
125:     methods.each do |method|
126:       method = method.to_s
127: 
128:       if allow_nil
129:         module_eval(          def #{method_prefix}#{method}(*args, &block)        # def customer_name(*args, &block)            if #{to} || #{to}.respond_to?(:#{method})         #   if client || client.respond_to?(:name)              #{to}.__send__(:#{method}, *args, &block)       #     client.__send__(:name, *args, &block)            end                                               #   end          end                                                 # end, file, line - 2)
130:       else
131:         exception = %(raise "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}")
132: 
133:         module_eval(          def #{method_prefix}#{method}(*args, &block)        # def customer_name(*args, &block)            #{to}.__send__(:#{method}, *args, &block)         #   client.__send__(:name, *args, &block)          rescue NoMethodError                                # rescue NoMethodError            if #{to}.nil?                                     #   if client.nil?              #{exception}                                    #     # add helpful message to the exception            else                                              #   else              raise                                           #     raise            end                                               #   end          end                                                 # end, file, line - 1)
134:       end
135:     end
136:   end
deprecate(*method_names) click to toggle source

Declare that a method has been deprecated.

  deprecate :foo
  deprecate :bar => 'message'
  deprecate :foo, :bar, :baz => 'warning!', :qux => 'gone!'
   # File lib/active_support/core_ext/module/deprecation.rb, line 6
6:   def deprecate(*method_names)
7:     ActiveSupport::Deprecation.deprecate_methods(self, *method_names)
8:   end
duplicable?() click to toggle source

Modules are not duplicable:

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

Note dup returned the same module object.

     # File lib/active_support/core_ext/object/duplicable.rb, line 103
103:   def duplicable?
104:     false
105:   end
instance_method_names(*args) click to toggle source
   # File lib/active_support/core_ext/module/method_names.rb, line 3
3:     def instance_method_names(*args)
4:       instance_methods(*args).map(&:to_s)
5:     end
local_constant_names() click to toggle source

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

    # File lib/active_support/core_ext/module/introspection.rb, line 85
85:   def local_constant_names
86:     local_constants.map { |c| c.to_s }
87:   end
local_constants() click to toggle source

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 lib/active_support/core_ext/module/introspection.rb, line 65
65:     def local_constants
66:       inherited = {}
67: 
68:       ancestors.each do |anc|
69:         next if anc == self
70:         anc.constants.each { |const| inherited[const] = anc.const_get(const) }
71:       end
72: 
73:       constants.select do |const|
74:         !inherited.key?(const) || inherited[const].object_id != const_get(const).object_id
75:       end
76:     end
mattr_accessor(*syms) click to toggle source

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!"

To opt out of the instance writer method, pass :instance_writer => false. To opt out of the instance reader method, pass :instance_reader => false. To opt out of both instance methods, pass :instance_accessor => false.

    # File lib/active_support/core_ext/module/attribute_accessors.rb, line 60
60:   def mattr_accessor(*syms)
61:     mattr_reader(*syms)
62:     mattr_writer(*syms)
63:   end
mattr_reader(*syms) click to toggle source
    # File lib/active_support/core_ext/module/attribute_accessors.rb, line 4
 4:   def mattr_reader(*syms)
 5:     options = syms.extract_options!
 6:     syms.each do |sym|
 7:       class_eval(        @@#{sym} = nil unless defined? @@#{sym}        def self.#{sym}          @@#{sym}        end, __FILE__, __LINE__ + 1)
 8: 
 9:       unless options[:instance_reader] == false || options[:instance_accessor] == false
10:         class_eval(          def #{sym}            @@#{sym}          end, __FILE__, __LINE__ + 1)
11:       end
12:     end
13:   end
mattr_writer(*syms) click to toggle source
    # File lib/active_support/core_ext/module/attribute_accessors.rb, line 25
25:   def mattr_writer(*syms)
26:     options = syms.extract_options!
27:     syms.each do |sym|
28:       class_eval(        def self.#{sym}=(obj)          @@#{sym} = obj        end, __FILE__, __LINE__ + 1)
29: 
30:       unless options[:instance_writer] == false || options[:instance_accessor] == false
31:         class_eval(          def #{sym}=(obj)            @@#{sym} = obj          end, __FILE__, __LINE__ + 1)
32:       end
33:     end
34:   end
method_names(*args) click to toggle source
   # File lib/active_support/core_ext/module/method_names.rb, line 7
7:     def method_names(*args)
8:       methods(*args).map(&:to_s)
9:     end
parent() click to toggle source

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
    # File lib/active_support/core_ext/module/introspection.rb, line 30
30:   def parent
31:     parent_name ? ActiveSupport::Inflector.constantize(parent_name) : Object
32:   end
parent_name() click to toggle source

Returns the name of the module containing this one.

  M::N.parent_name # => "M"
    # File lib/active_support/core_ext/module/introspection.rb, line 7
 7:   def parent_name
 8:     unless defined? @parent_name
 9:       @parent_name = name =~ /::[^:]+\Z/ ? $`.freeze : nil
10:     end
11:     @parent_name
12:   end
parents() click to toggle source

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]
    # File lib/active_support/core_ext/module/introspection.rb, line 47
47:   def parents
48:     parents = []
49:     if parent_name
50:       parts = parent_name.split('::')
51:       until parts.empty?
52:         parents << ActiveSupport::Inflector.constantize(parts * '::')
53:         parts.pop
54:       end
55:     end
56:     parents << Object unless parents.include? Object
57:     parents
58:   end
qualified_const_defined?(path, search_parents=true) click to toggle source
    # File lib/active_support/core_ext/module/qualified_const.rb, line 37
37:     def qualified_const_defined?(path, search_parents=true)
38:       QualifiedConstUtils.raise_if_absolute(path)
39: 
40:       QualifiedConstUtils.names(path).inject(self) do |mod, name|
41:         return unless mod.const_defined?(name, search_parents)
42:         mod.const_get(name)
43:       end
44:       return true
45:     end
qualified_const_defined?(path) click to toggle source
    # File lib/active_support/core_ext/module/qualified_const.rb, line 27
27:     def qualified_const_defined?(path)
28:       QualifiedConstUtils.raise_if_absolute(path)
29: 
30:       QualifiedConstUtils.names(path).inject(self) do |mod, name|
31:         return unless mod.const_defined?(name)
32:         mod.const_get(name)
33:       end
34:       return true
35:     end
qualified_const_get(path) click to toggle source
    # File lib/active_support/core_ext/module/qualified_const.rb, line 48
48:   def qualified_const_get(path)
49:     QualifiedConstUtils.raise_if_absolute(path)
50: 
51:     QualifiedConstUtils.names(path).inject(self) do |mod, name|
52:       mod.const_get(name)
53:     end
54:   end
qualified_const_set(path, value) click to toggle source
    # File lib/active_support/core_ext/module/qualified_const.rb, line 56
56:   def qualified_const_set(path, value)
57:     QualifiedConstUtils.raise_if_absolute(path)
58: 
59:     const_name = path.demodulize
60:     mod_name = path.deconstantize
61:     mod = mod_name.empty? ? self : qualified_const_get(mod_name)
62:     mod.const_set(const_name, value)
63:   end
redefine_method(method, &block) click to toggle source
    # File lib/active_support/core_ext/module/remove_method.rb, line 12
12:   def redefine_method(method, &block)
13:     remove_possible_method(method)
14:     define_method(method, &block)
15:   end
remove_possible_method(method) click to toggle source
    # File lib/active_support/core_ext/module/remove_method.rb, line 2
 2:   def remove_possible_method(method)
 3:     if method_defined?(method) || private_method_defined?(method)
 4:       remove_method(method)
 5:     end
 6:   rescue NameError
 7:     # If the requested method is defined on a superclass or included module,
 8:     # method_defined? returns true but remove_method throws a NameError.
 9:     # Ignore this.
10:   end
synchronize(*methods) click to toggle source

Synchronize access around a method, delegating synchronization to a particular mutex. A mutex (either a Mutex, or any object that responds to # 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
    # File lib/active_support/core_ext/module/synchronization.rb, line 20
20:   def synchronize(*methods)
21:     options = methods.extract_options!
22:     unless options.is_a?(Hash) && with = options[:with]
23:       raise ArgumentError, "Synchronization needs a mutex. Supply an options hash with a :with key as the last argument (e.g. synchronize :hello, :with => :@mutex)."
24:     end
25: 
26:     methods.each do |method|
27:       aliased_method, punctuation = method.to_s.sub(/([?!=])$/, ''), $1
28: 
29:       if method_defined?("#{aliased_method}_without_synchronization#{punctuation}")
30:         raise ArgumentError, "#{method} is already synchronized. Double synchronization is not currently supported."
31:       end
32: 
33:       module_eval(        def #{aliased_method}_with_synchronization#{punctuation}(*args, &block)     # def expire_with_synchronization(*args, &block)          #{with}.synchronize do                                                    #   @@lock.synchronize do            #{aliased_method}_without_synchronization#{punctuation}(*args, &block)  #     expire_without_synchronization(*args, &block)          end                                                                       #   end        end                                                                         # end, __FILE__, __LINE__ + 1)
34: 
35:       alias_method_chain method, :synchronization
36:     end
37:   end

Private Instance Methods

attr_internal_define(attr_name, type) click to toggle source
    # File lib/active_support/core_ext/module/attr_internal.rb, line 29
29:     def attr_internal_define(attr_name, type)
30:       internal_name = attr_internal_ivar_name(attr_name).sub(/\A@/, '')
31:       class_eval do # class_eval is necessary on 1.9 or else the methods a made private
32:         # use native attr_* methods as they are faster on some Ruby implementations
33:         send("attr_#{type}", internal_name)
34:       end
35:       attr_name, internal_name = "#{attr_name}=", "#{internal_name}=" if type == :writer
36:       alias_method attr_name, internal_name
37:       remove_method internal_name
38:     end
attr_internal_ivar_name(attr) click to toggle source
    # File lib/active_support/core_ext/module/attr_internal.rb, line 25
25:     def attr_internal_ivar_name(attr)
26:       Module.attr_internal_naming_format % attr
27:     end

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