GitHub - colinta/einstein-enum: Enums with associated values and polymorphic behavior, inspired by Swift.

class Api < Enum
  value :Status
  value :Posts, raw_value: :posts
  # these represent an endpoint for "user detail", either by id or username
  value :User, Fixnum
  value :User, String

  def url
    # inside this method, the constants "Status" and methods "User" are defined
    # to return the appropriate enum values/matchers
    case self
    when Status
      "/status"
    when User(-1)  # one off values can be matched!
      "/users/by_role/admin"
    when User(Fixnum)
      # you can access the values using array access
      id = self[0]
      "/users/by_id/#{id}"
    when User(String)
      username = self[0]
      "/users/by_name/#{username}"
    when Posts
      "/posts"
    else
      nil
    end
  end

end


status_endpoint = Api.Status
user_endpoint = Api.User(2)  # if you tried `Api.User` you would get a 'value not defined' expection


# matching is really where it's at:
case status_endpoint
# simple enum values
when Api.Status
when Api.Posts
# here is the cool "polymorphic" matching.  I have not seen any other Ruby Enum
# gems offer this:
when Api.User(Fixnum)
when Api.User(String)
end


# the ability to have methods associated with the enum values is very handy, and
# adds object-oriented ideas to the boring old 'enum' type.
puts status_endpoint.url  # => https://api.api.com/api/v1/status

class Api < Enum
  value :User, id: Fixnum
end

user_endpoint = Api.User(id: 2)

id = user_endpoint[:id]
id = user_endpoint.id