Class: Module
- Defined in:
- motion/core_ext/module/aliasing.rb,
motion/core_ext/module/anonymous.rb,
motion/core_ext/module/reachable.rb,
motion/core_ext/module/delegation.rb,
motion/core_ext/module/attr_internal.rb,
motion/core_ext/module/introspection.rb,
motion/core_ext/module/remove_method.rb,
motion/core_ext/module/attribute_accessors.rb
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’ public methods as your own.
-
#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.
-
#reachable? ⇒ Boolean
:nodoc:.
- #redefine_method(method, &block) ⇒ Object
- #remove_possible_method(method) ⇒ Object
Class Attribute Details
.attr_internal_naming_format ⇒ Object
Returns the value of attribute attr_internal_naming_format.
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# File 'motion/core_ext/module/attr_internal.rb', line 20 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.
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 'motion/core_ext/module/aliasing.rb', line 62 def alias_attribute(new_name, old_name) module_exec do define_method(new_name) { self.send(old_name) } # def subject; self.title; end define_method("#{new_name}?") { self.send("#{old_name}?") } # def subject?; self.title?; end define_method("#{new_name}=") { |v| self.send("#{old_name}=", v) } # def subject=(v); self.title = v; end end 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.
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# File 'motion/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 = "#{aliased_target}_with_#{feature}#{punctuation}" without_method = "#{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 # => nil
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 'motion/core_ext/module/anonymous.rb', line 16 def anonymous? name.nil? 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 'motion/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 'motion/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 'motion/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’ public 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
It’s also possible to delegate a method to the class by using :class
:
class Foo
def self.hello
"world"
end
delegate :hello, to: :class
end
Foo.new.hello # => "world"
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)
@bar =
end
delegate :zoo, to: :bar
end
Foo.new.zoo # raises NoMethodError exception (you called nil.zoo)
class Foo
attr_accessor :bar
def initialize( = nil)
@bar =
end
delegate :zoo, to: :bar, allow_nil: true
end
Foo.new.zoo # returns nil
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# File 'motion/core_ext/module/delegation.rb', line 115 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, allow_nil = .values_at(:prefix, :allow_nil) unguarded = !allow_nil if prefix == true && to =~ /^[^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 reference, *hierarchy = to.to_s.split('.') entry = resolver = case reference when 'self' ->(_self) { _self } when /^@@/ ->(_self) { _self.class.class_variable_get(reference) } when /^@/ ->(_self) { _self.instance_variable_get(reference) } when /^[A-Z]/ ->(_self) { if reference.to_s =~ /::/ then reference.constantize else _self.class.const_get(reference) end } else ->(_self) { _self.send(reference) } end resolver = ->(_self) { hierarchy.reduce(entry.call(_self)) { |obj, method| obj.public_send(method) } } unless hierarchy.empty? methods.each do |method| module_exec do # def customer_name(*args, &block) # begin # if unguarded || client || client.respond_to?(:name) # client.name(*args, &block) # end # rescue client.nil? && NoMethodError # raise "..." # end # end define_method("#{method_prefix}#{method}") do |*args, &block| target = resolver.call(self) if unguarded || target || target.respond_to?(method) begin target.public_send(method, *args, &block) rescue target.nil? && NoMethodError # only rescue NoMethodError when target is nil raise "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: #{self.inspect}" end end end end end end |
#local_constants ⇒ Object
:nodoc:
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# File 'motion/core_ext/module/introspection.rb', line 57 def local_constants #:nodoc: constants(false) 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"
end
AppConfiguration.google_api_key # => "123456789"
AppConfiguration.google_api_key = "overriding the api key!"
AppConfiguration.google_api_key # => "overriding the api key!"
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# File 'motion/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 'motion/core_ext/module/attribute_accessors.rb', line 2 def mattr_reader(*syms) receiver = self = syms. syms.each do |sym| raise NameError.new('invalid attribute name') unless sym =~ /^[_A-Za-z]\w*$/ class_exec do unless class_variable_defined?("@@#{sym}") class_variable_set("@@#{sym}", nil) end define_singleton_method sym do class_variable_get("@@#{sym}") end end unless [:instance_reader] == false || [:instance_accessor] == false class_exec do define_method sym do receiver.class_variable_get("@@#{sym}") end end end end end |
#mattr_writer(*syms) ⇒ Object
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# File 'motion/core_ext/module/attribute_accessors.rb', line 27 def mattr_writer(*syms) receiver = self = syms. syms.each do |sym| raise NameError.new('invalid attribute name') unless sym =~ /^[_A-Za-z]\w*$/ class_exec do define_singleton_method "#{sym}=" do |obj| class_variable_set("@@#{sym}", obj) end end unless [:instance_writer] == false || [:instance_accessor] == false class_exec do define_method "#{sym}=" do |obj| receiver.class_variable_set("@@#{sym}", obj) end end end end end |
#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 'motion/core_ext/module/introspection.rb', line 28 def parent parent_name ? parent_name.constantize : Object end |
#parent_name ⇒ Object
Returns the name of the module containing this one.
M::N.parent_name # => "M"
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# File 'motion/core_ext/module/introspection.rb', line 5 def parent_name if defined? @parent_name @parent_name else @parent_name = name =~ /::[^:]+\Z/ ? $`.freeze : nil end 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 'motion/core_ext/module/introspection.rb', line 44 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 |
#reachable? ⇒ Boolean
:nodoc:
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# File 'motion/core_ext/module/reachable.rb', line 2 def reachable? #:nodoc: !anonymous? && name.safe_constantize.equal?(self) end |
#redefine_method(method, &block) ⇒ Object
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# File 'motion/core_ext/module/remove_method.rb', line 8 def redefine_method(method, &block) remove_possible_method(method) define_method(method, &block) end |
#remove_possible_method(method) ⇒ Object
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# File 'motion/core_ext/module/remove_method.rb', line 2 def remove_possible_method(method) if method_defined?(method) || private_method_defined?(method) undef_method(method) end end |