fluke/devops-service/db/validators/base.rb

class Validators::Base

  def initialize(model, options={})
    @model = model
    @options = options
  end

  def validate!
    raise InvalidRecord.new(message) unless valid?
  end

  def valid?
    raise 'override me'
  end

  def message
    raise 'override me'
  end

  class << self
    private

    # this method delegates @valid? and @message methods to helper validator, passed as block
    def delegate_to_helper_validator(&block)

      define_method :helper_validator do
        @helper_validator ||= self.instance_eval(&block)
      end

      define_method :valid? do
        self.helper_validator.valid?
      end

      define_method :message do
        self.helper_validator.message
      end
    end
  end

end