original_simple_enum.rb

# ref: https://www.paweldabrowski.com/articles/rails-enum-under-the-hood

module Channel
  def enum_channels(mappings)
    mappings.each_pair do |name, values|
      singleton_class.define_method("#{name}_hash") { values }

      values.each_pair do |key, value|
        define_method("#{key}?") { self.status == value  } 
      end
    end
  end
end


class Applicant
  extend Channel
  
  enum_channels status: { invite: 0, active: 1 }
  
  attr_reader :status
  
  def initialize(status)
    @status = status
  end
end


app = Applicant.new(0)
puts app.active? # false
puts app.invite? # true

app = Applicant.new(1)
puts app.active? # true
puts app.invite? # false

puts Applicant.status_hash