railsのenumにも使えるやーつ

application_enum.rb

class ApplicationEnum
  class << self
    attr_writer :attribute_names

    def all
      @all ||= Set.new
    end

    def attribute_names
      @attribute_names ||= Set.new
    end

    def enums
      all.map{|e| [e.key, e.id] }.to_h
    end

    def [](k)
      all.find{|e| e.is? k }
    end

    def define(**attributes)
      all << new(**attributes)
    end
  end

  attr_reader :id, :key

  def initialize(id:, key:, **attributes)
    attributes.symbolize_keys!
    self.class.attribute_names += Set[*attributes.keys]

    @id, @key, @attributes = id, key.to_s, attributes.with_indifferent_access
  end

  def method_missing(name, *args)
    if self.class.attribute_names.include? name.to_sym
      @attributes[name]
    else
      super
    end
  end

  def is?(k)
    id == k || key == k.to_s
  end

  def eql?(other)
    @id == other.id
  end

  def hash
    @id.hash
  end
end