What is the use of 'abstract_method'?

What is the use of 'abstract_method' in rails?

--Rahul

http://www.noobkit.com/show/ruby/gems/io/rio/module/abstract_method.html defines it as: "abstract_method(symbol, …) extends Module defines a method which raises AbstractMethodCalled used in a base class to ensure that subclasses define an implementation"

It is used to cap the parent class of an inheritance.

so if class Foo < Bar

and Bar.some_method you want it to have to be defined in all subclasess (Foo and others...) you do like such:

class Bar   def some_method     abstract_method   end end

then all subclasses must implement some_method or it will complain when being called (Note, untill it is called, everything is sweet, this can casue bugs...)