new | -> | postinitialize_new |
Creates a class-variable attribute that can be accessed both on an instance and class level.
NOTE This used to be a Module method. But turns out it does not work as expected when included. The class-level method is not carried along. So it is now just a Class method. Accordingly, mattr has been deprecated.
CREDIT: David Heinemeier Hansson
Creates a class-variable attr_accessor that can be accessed both on an instance and class level.
class MyClass cattr_accessor :a end MyClass.a = 10 MyClass.a #=> 10 mc = MyClass.new mc.a #=> 10
CREDIT: David Heinemeier Hansson
Creates a class-variable attr_reader that can be accessed both on an instance and class level.
class MyClass @@a = 10 cattr_reader :a end MyClass.a #=> 10 MyClass.new.a #=> 10
CREDIT: David Heinemeier Hansson
Creates a class-variable attr_writer that can be accessed both on an instance and class level.
class MyClass cattr_writer :a def a @@a end end MyClass.a = 10 MyClass.a #=> 10 MyClass.new.a = 29 MyClass.a #=> 29
CREDIT: David Heinemeier Hansson
For Class, class_extend is the same as class_eval. The alternative is to "undef_method :class_extend", but this seems uneccessarily limited.
List all descedents of this class.
class X ; end class A < X; end class B < X; end X.descendents #=> [A,B]
NOTE: This is a intesive operation. Do not expect it to be super fast.
Prepend an "aspect module" to a class.
class Firetruck def put_out_fire(option) "Put out #{option}" end end module FastFiretruck def put_out_fire(option) super("very #{option}!") end end Firetruck.prepend(FastFiretruck) ft = Firetruck.new ft.put_out_fire('fast') #=> "Put out very fast!"
Implementation of this method has some limitations, in that it works by overriding new and allocate.
CREDIT: Trans
TODO: Perhaps rename this to preallocate, b/c of the way it works. It is not really a clean prepend, like that of Module#prepend.