defmulti

NOTE: This gem runs perfectly fine on Ruby 1.9.1.

This gem is an implementation of multi-method dispatching in Ruby. This allows you to define multiple blocks of code that can execute, depending on certain conditions:

 require "defmulti"
  
  class Factorial
    class << self
      defmulti :generate,
        lambda {|n| n == 1} => 1,
        nil                 => lambda {|n| n * generate(n - 1) }
    end
  end
  
  Factorial.generate 1
  #=> 1
  Factorial.generate 2
  #=> 2
  Factorial.generate 3
  #=> 6
  Factorial.generate 4
  #=> 24
  Factorial.generate 5
  #=> 120

This is a thought experiment. I was thinking about a language in which the if/then/else construct would not exist. How would such a language evolve? That is what I was trying to determine.

NOTE: This isn’t ready for production use. Neither is it used in production anywhere.

If you want to run the tests, you’ll need the Dfect library.