Ruby Language Singleton Class Message Propagation with Singleton Class
Example
Instances never contain a method they only carry data. However we can define a singleton class for any object including an instance of a class.
When a message is passed to an object (method is called) Ruby first checks if a singleton class is defined for that object and if it can reply to that message otherwise Ruby checks instance's class' ancestors chain and walks up on that.
class Example
def foo
:example
end
end
Example.new.foo #=> :example
module PrependedModule
def foo
:prepend
end
end
class Example
prepend PrependedModule
end
Example.ancestors #=> [Prepended, Example, Object, Kernel, BasicObject]
e = Example.new
e.foo #=> :prepended
def e.foo
:singleton
end
e.foo #=> :singleton
