openproject/lib/widget/base.rb

class Widget::Base < Widget
  attr_reader :engine

  def initialize(query)
    @query = query
    @engine = query.class
  end

  def render
    raise NotImplementedError,  "#render is missing in my subclass"
  end

  def render_with_options(options = {}, &block)
    if canvas = options[:to]
      canvas << "\n" << render(&block)
    else
      render(&block)
    end
  end
end