Another enum-ish example

some_types.rb

class SomeTypes
  @all = [
    ["TypeA",  "Type A"],
    ["Type B", "Type B"],
  ]

  Type = Struct.new(:type, :name, :slug, :sym) do
    alias_method :to_ary, :to_a

    # allows Type to be used for ifnone option in .find
    def self.call
      new
    end
  end

  Type.members.each do |member|
    # define named helpers to return all i.e. .types, .names, .slugs
    define_singleton_method member.to_s.pluralize do
      all.map(&member)
    end

    # named finder i.e. .by_type, .by_name, .by_slug
    define_singleton_method "by_#{member}" do |cond|
      find(member => cond)
    end
  end

  ALL = Array.new.tap do |all|
    @all.each do |ary|
      type = ary.first
      name = ary.last
      all << Type.new(type, name, type.parameterize, type.underscore.to_sym)
    end
  end

  ALL.each do |t|
    # define constant for each type
    const_set(t.type.upcase, t.type)
  end

  def self.all
    ALL
  end

  def self.each(&block)
    all.each(&block)
  end

  def self.find(cond)
    cond = { type: cond } if cond.is_a?(String)
    cond = cond.first
    all.find(Type){ |t| t.send(cond.first) == cond.last }
  end

  def self.[](cond)
    find(cond)
  end

  def self.to_options
    all.map{ |t| [t.name, t.type] }
  end
end