class method self.new

# File activemodel/lib/active_model/secure_password.rb, line 115
      def initialize(attribute)
        attr_reader attribute

        define_method("#{attribute}=") do |unencrypted_password|
          if unencrypted_password.nil?
            instance_variable_set("@#{attribute}", nil)
            self.public_send("#{attribute}_digest=", nil)
          elsif !unencrypted_password.empty?
            instance_variable_set("@#{attribute}", unencrypted_password)
            cost = ActiveModel::SecurePassword.min_cost ? BCrypt::Engine::MIN_COST : BCrypt::Engine.cost
            self.public_send("#{attribute}_digest=", BCrypt::Password.create(unencrypted_password, cost: cost))
          end
        end

        define_method("#{attribute}_confirmation=") do |unencrypted_password|
          instance_variable_set("@#{attribute}_confirmation", unencrypted_password)
        end

        # Returns +self+ if the password is correct, otherwise +false+.
        #
        #   class User < ActiveRecord::Base
        #     has_secure_password validations: false
        #   end
        #
        #   user = User.new(name: 'david', password: 'mUc3m00RsqyRe')
        #   user.save
        #   user.authenticate_password('notright')      # => false
        #   user.authenticate_password('mUc3m00RsqyRe') # => user
        define_method("authenticate_#{attribute}") do |unencrypted_password|
          attribute_digest = public_send("#{attribute}_digest")
          attribute_digest.present? && BCrypt::Password.new(attribute_digest).is_password?(unencrypted_password) && self
        end

        alias_method :authenticate, :authenticate_password if attribute == :password
      end