'abstract.rb' is a library which enable you to define abstract method in Ruby.

The followings are examples:

## example1. (shorter notation)
require 'rubygems' # if installed with 'gem install'
require 'abstract'
class Foo
abstract_method 'arg1, arg2=""', :method1, :method2, :method3
end

## example2. (RDoc friendly notation)
require 'rubygems' # if installed with 'gem install'
require 'abstract'
class Bar
# ... method1 description ...
def method1(arg1, arg2="")
not_implemented
end
# ... method2 description ...
def method2(arg1, arg2="")
not_implemented
end
end


Abstract method makes your code more descriptive.
It is useful even for dynamic language such as Ruby.