generate_token_for.rb

#!/usr/bin/env ruby

require 'securerandom'

# Example
#   class User
#     include GenerateTokenFor[:confirmation_token]
#   end
#
#   @user = User.new
#   @user.confirmation_token #=> nil
#   @user.save
#   @user.confirmation_token #=> "1cf694f7-a0db-46f7-b98f-a50cbf443760"
module GenerateTokenFor
  def self.[](column)
    Module.new do
      const_set(:COLUMN, column)

      def generate_token!
        send("#{self.class.const_get(:COLUMN)}=", SecureRandom.uuid)
      end
    end
  end
end

class A
  include GenerateTokenFor[:token]

  attr_accessor :token
end

class B
  include GenerateTokenFor[:confirmation_token]

  attr_accessor :confirmation_token
end

a = A.new
p a.token
a.generate_token!
p a.token

b = B.new
p b.confirmation_token
b.generate_token!
p b.confirmation_token