A handy enumerable to integer mapper creator

class EnumerableAttribute

  attr_reader :values

  def initialize(*args)

    @values = Hash.new

    0.upto(args.size-1) do |i|
      @values[args[i].to_s] = i
    end

    @values.each do |key, value|
      EnumerableAttribute.class_eval do
        define_method key do
          value
        end
      end
    end
  end
end

This class allows the dynamical creation of enumerable types mapped to integers in the database, starting from 0. The constructor will take a list of symbols representing the keys and will create a Hash that will map each key to one integer value. Once created, we can have access to the Hash via the method values or to the integer value of each key via the method called like the symbol.

E.g.

class Car
  include EnumerableAttribute
end

>> engine_type = Car::EnumerableAttribute.new(:diesel, :gasoline, :solar)
=> #<EnumerableAttribute::EnumerableAttribute:0x2467f5c @values={"diesel"=>0, "gasoline"=>1, "solar" =>2}>

>> engine_type.values
=> {"diesel"=>0, "gasoline"=>1, "solar" =>2}

>> engine_type.gasoline
=> "1

Enjoy!