Advanced Java-like enums in Ruby

Question

First of all, this is not a duplicate of Enums in Ruby :)

The accepted answer of that question suggests this as a good way to represent enums in Ruby:

cl         


        

Answer 1

class MyEnum
  attr_accessor :value
  def initialize(value)
    @value = value
  end

  VALUE1 = new("Value 1")
  VALUE2 = new("Value 2")

  class << self
    private :new
  end
end

MyEnum::VALUE2 # Enum with value "Value 2"
MyEnum.new # Error

A more elaborate solution that allows you to define arbitrary "enum classes" and also gives you ordinal():

def enum(*values, &class_body)
  Class.new( Class.new(&class_body) ) do
    attr_reader :ordinal

    def initialize(ordinal, *args, &blk)
      super(*args, &blk)
      @ordinal = ordinal
    end

    values.each_with_index do |(name, *parameters), i|
      const_set(name, new(i, *parameters))
    end

    class < "Value 1"
MyEnum::VALUE2.ordinal #=> 1