Class: Module
- Defined in:
- activesupport/lib/active_support/core_ext/module/qualified_const.rb,
activesupport/lib/active_support/core_ext/module/aliasing.rb,
activesupport/lib/active_support/core_ext/module/reachable.rb,
activesupport/lib/active_support/core_ext/module/anonymous.rb,
activesupport/lib/active_support/core_ext/object/duplicable.rb,
activesupport/lib/active_support/core_ext/module/delegation.rb,
activesupport/lib/active_support/core_ext/module/deprecation.rb,
activesupport/lib/active_support/core_ext/module/method_names.rb,
activesupport/lib/active_support/core_ext/module/remove_method.rb,
activesupport/lib/active_support/core_ext/module/introspection.rb,
activesupport/lib/active_support/core_ext/module/attr_internal.rb,
activesupport/lib/active_support/core_ext/module/synchronization.rb,
activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
Overview
Extends the API for constants to be able to deal with qualified names. Arguments are assumed to be relative to the receiver.
– Qualified names are required to be relative because we are extending existing methods that expect constant names, ie, relative paths of length 1. For example, Object.const_get(“::String”) raises NameError and so does qualified_const_get. ++
Class Attribute Summary collapse
-
.attr_internal_naming_format ⇒ Object
Returns the value of attribute attr_internal_naming_format.
Instance Method Summary collapse
-
#alias_attribute(new_name, old_name) ⇒ Object
Allows you to make aliases for attributes, which includes getter, setter, and query methods.
-
#alias_method_chain(target, feature) {|aliased_target, punctuation| ... } ⇒ Object
Encapsulates the common pattern of:.
-
#anonymous? ⇒ Boolean
A module may or may not have a name.
-
#attr_internal_accessor(*attrs) ⇒ Object
(also: #attr_internal)
Declares an attribute reader and writer backed by an internally-named instance variable.
-
#attr_internal_reader(*attrs) ⇒ Object
Declares an attribute reader backed by an internally-named instance variable.
-
#attr_internal_writer(*attrs) ⇒ Object
Declares an attribute writer backed by an internally-named instance variable.
-
#delegate(*methods) ⇒ Object
Provides a delegate class method to easily expose contained objects’ methods as your own.
-
#deprecate(*method_names) ⇒ Object
Declare that a method has been deprecated.
-
#duplicable? ⇒ Boolean
Modules are not duplicable:.
-
#local_constant_names ⇒ Object
Returns the names of the constants defined locally rather than the constants themselves.
-
#local_constants ⇒ Object
:nodoc:.
-
#mattr_accessor(*syms) ⇒ Object
Extends the module object with module and instance accessors for class attributes, just like the native attr* accessors for instance attributes.
- #mattr_reader(*syms) ⇒ Object
- #mattr_writer(*syms) ⇒ Object
-
#parent ⇒ Object
Returns the module which contains this one according to its name.
-
#parent_name ⇒ Object
Returns the name of the module containing this one.
-
#parents ⇒ Object
Returns all the parents of this module according to its name, ordered from nested outwards.
- #qualified_const_defined?(path, search_parents = true) ⇒ Boolean
- #qualified_const_get(path) ⇒ Object
- #qualified_const_set(path, value) ⇒ Object
-
#reachable? ⇒ Boolean
:nodoc:.
- #redefine_method(method, &block) ⇒ Object
- #remove_possible_method(method) ⇒ Object
-
#synchronize(*methods) ⇒ Object
Synchronize access around a method, delegating synchronization to a particular mutex.
Class Attribute Details
.attr_internal_naming_format ⇒ Object
Returns the value of attribute attr_internal_naming_format
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# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 21 def attr_internal_naming_format @attr_internal_naming_format end |
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 63 def alias_attribute(new_name, old_name) module_eval " def \#{new_name}; self.\#{old_name}; end # def subject; self.title; end\n def \#{new_name}?; self.\#{old_name}?; end # def subject?; self.title?; end\n def \#{new_name}=(v); self.\#{old_name} = v; end # def subject=(v); self.title = v; end\n STR\nend\n", __FILE__, __LINE__ + 1 |
#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.
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# File 'activesupport/lib/active_support/core_ext/module/aliasing.rb', line 23 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 |
#anonymous? ⇒ Boolean
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"
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# File 'activesupport/lib/active_support/core_ext/module/anonymous.rb', line 19 def anonymous? # Uses blank? because the name of an anonymous class is an empty # string in 1.8, and nil in 1.9. name.blank? end |
#attr_internal_accessor(*attrs) ⇒ Object Also known as: attr_internal
Declares an attribute reader and writer backed by an internally-named instance variable.
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# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 14 def attr_internal_accessor(*attrs) attr_internal_reader(*attrs) attr_internal_writer(*attrs) end |
#attr_internal_reader(*attrs) ⇒ Object
Declares an attribute reader backed by an internally-named instance variable.
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# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 3 def attr_internal_reader(*attrs) attrs.each {|attr_name| attr_internal_define(attr_name, :reader)} end |
#attr_internal_writer(*attrs) ⇒ Object
Declares an attribute writer backed by an internally-named instance variable.
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# File 'activesupport/lib/active_support/core_ext/module/attr_internal.rb', line 8 def attr_internal_writer(*attrs) attrs.each {|attr_name| attr_internal_define(attr_name, :writer)} end |
#delegate(*methods) ⇒ Object
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( = nil)
=
end
delegate :zoo, :to => :bar
end
Foo.new.zoo # raises NoMethodError exception (you called nil.zoo)
class Foo
attr_accessor :bar
def initialize( = nil)
=
end
delegate :zoo, :to => :bar, :allow_nil => true
end
Foo.new.zoo # returns nil
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# File 'activesupport/lib/active_support/core_ext/module/delegation.rb', line 104 def delegate(*methods) = methods.pop unless .is_a?(Hash) && to = [:to] raise ArgumentError, "Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, :to => :greeter)." end prefix, to, allow_nil = [:prefix], [:to], [:allow_nil] if prefix == true && to.to_s =~ /^[^a-z_]/ raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method." end method_prefix = if prefix "#{prefix == true ? to : prefix}_" else '' end file, line = caller.first.split(':', 2) line = line.to_i methods.each do |method| method = method.to_s if allow_nil module_eval(" def \#{method_prefix}\#{method}(*args, &block) # def customer_name(*args, &block)\n if \#{to} || \#{to}.respond_to?(:\#{method}) # if client || client.respond_to?(:name)\n \#{to}.__send__(:\#{method}, *args, &block) # client.__send__(:name, *args, &block)\n end # end\n end # end\n EOS\n else\n exception = %(raise \"\#{self}#\#{method_prefix}\#{method} delegated to \#{to}.\#{method}, but \#{to} is nil: \\\#{self.inspect}\")\n\n module_eval(<<-EOS, file, line - 1)\n def \#{method_prefix}\#{method}(*args, &block) # def customer_name(*args, &block)\n \#{to}.__send__(:\#{method}, *args, &block) # client.__send__(:name, *args, &block)\n rescue NoMethodError # rescue NoMethodError\n if \#{to}.nil? # if client.nil?\n \#{exception} # # add helpful message to the exception\n else # else\n raise # raise\n end # end\n end # end\n EOS\n end\n end\nend\n", file, line - 2) |
#deprecate(*method_names) ⇒ Object
Declare that a method has been deprecated.
deprecate :foo
deprecate :bar => 'message'
deprecate :foo, :bar, :baz => 'warning!', :qux => 'gone!'
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# File 'activesupport/lib/active_support/core_ext/module/deprecation.rb', line 6 def deprecate(*method_names) ActiveSupport::Deprecation.deprecate_methods(self, *method_names) end |
#duplicable? ⇒ Boolean
Modules are not duplicable:
m = Module.new # => #<Module:0x10328b6e0>
m.dup # => #<Module:0x10328b6e0>
Note dup
returned the same module object.
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# File 'activesupport/lib/active_support/core_ext/object/duplicable.rb', line 103 def duplicable? false end |
#local_constant_names ⇒ Object
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_constants ⇒ Object
: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 |
#mattr_accessor(*syms) ⇒ Object
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.
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# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 60 def mattr_accessor(*syms) mattr_reader(*syms) mattr_writer(*syms) end |
#mattr_reader(*syms) ⇒ Object
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# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 4 def mattr_reader(*syms) = syms. syms.each do |sym| class_eval(" @@\#{sym} = nil unless defined? @@\#{sym}\n\n def self.\#{sym}\n @@\#{sym}\n end\n EOS\n\n unless options[:instance_reader] == false || options[:instance_accessor] == false\n class_eval(<<-EOS, __FILE__, __LINE__ + 1)\n def \#{sym}\n @@\#{sym}\n end\n EOS\n end\n end\nend\n", __FILE__, __LINE__ + 1) |
#mattr_writer(*syms) ⇒ Object
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# File 'activesupport/lib/active_support/core_ext/module/attribute_accessors.rb', line 25 def mattr_writer(*syms) = syms. syms.each do |sym| class_eval(" def self.\#{sym}=(obj)\n @@\#{sym} = obj\n end\n EOS\n\n unless options[:instance_writer] == false || options[:instance_accessor] == false\n class_eval(<<-EOS, __FILE__, __LINE__ + 1)\n def \#{sym}=(obj)\n @@\#{sym} = obj\n end\n EOS\n end\n end\nend\n", __FILE__, __LINE__ + 1) |
#parent ⇒ Object
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
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# File 'activesupport/lib/active_support/core_ext/module/introspection.rb', line 30 def parent parent_name ? ActiveSupport::Inflector.constantize(parent_name) : Object end |
#parent_name ⇒ Object
Returns the name of the module containing this one.
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 |
#parents ⇒ Object
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]
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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 << ActiveSupport::Inflector.constantize(parts * '::') parts.pop end end parents << Object unless parents.include? Object parents end |
#qualified_const_defined?(path, search_parents = true) ⇒ Boolean
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# File 'activesupport/lib/active_support/core_ext/module/qualified_const.rb', line 27 def qualified_const_defined?(path) QualifiedConstUtils.raise_if_absolute(path) QualifiedConstUtils.names(path).inject(self) do |mod, name| return unless mod.const_defined?(name) mod.const_get(name) end return true end |
#qualified_const_get(path) ⇒ Object
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# File 'activesupport/lib/active_support/core_ext/module/qualified_const.rb', line 48 def qualified_const_get(path) QualifiedConstUtils.raise_if_absolute(path) QualifiedConstUtils.names(path).inject(self) do |mod, name| mod.const_get(name) end end |
#qualified_const_set(path, value) ⇒ Object
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# File 'activesupport/lib/active_support/core_ext/module/qualified_const.rb', line 56 def qualified_const_set(path, value) QualifiedConstUtils.raise_if_absolute(path) const_name = path.demodulize mod_name = path.deconstantize mod = mod_name.empty? ? self : qualified_const_get(mod_name) mod.const_set(const_name, value) end |
#reachable? ⇒ Boolean
:nodoc:
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# File 'activesupport/lib/active_support/core_ext/module/reachable.rb', line 5 def reachable? #:nodoc: !anonymous? && name.safe_constantize.equal?(self) end |
#redefine_method(method, &block) ⇒ Object
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# File 'activesupport/lib/active_support/core_ext/module/remove_method.rb', line 12 def redefine_method(method, &block) remove_possible_method(method) define_method(method, &block) end |
#remove_possible_method(method) ⇒ Object
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# File 'activesupport/lib/active_support/core_ext/module/remove_method.rb', line 2 def remove_possible_method(method) if method_defined?(method) || private_method_defined?(method) remove_method(method) end rescue NameError # If the requested method is defined on a superclass or included module, # method_defined? returns true but remove_method throws a NameError. # Ignore this. end |
#synchronize(*methods) ⇒ 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
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# File 'activesupport/lib/active_support/core_ext/module/synchronization.rb', line 20 def synchronize(*methods) = methods. unless .is_a?(Hash) && with = [:with] raise ArgumentError, "Synchronization needs a mutex. Supply an options hash with a :with key as the last argument (e.g. synchronize :hello, :with => :@mutex)." end methods.each do |method| aliased_method, punctuation = method.to_s.sub(/([?!=])$/, ''), $1 if method_defined?("#{aliased_method}_without_synchronization#{punctuation}") raise ArgumentError, "#{method} is already synchronized. Double synchronization is not currently supported." end module_eval(" def \#{aliased_method}_with_synchronization\#{punctuation}(*args, &block) # def expire_with_synchronization(*args, &block)\n \#{with}.synchronize do # @@lock.synchronize do\n \#{aliased_method}_without_synchronization\#{punctuation}(*args, &block) # expire_without_synchronization(*args, &block)\n end # end\n end # end\n EOS\n\n alias_method_chain method, :synchronization\n end\nend\n", __FILE__, __LINE__ + 1) |