module Sass::Callbacks

def self.extended(base)
  base.send(:include, InstanceMethods)
end

def define_callback(name)
  class_eval <<RUBY, __FILE__, __LINE__ + 1
on_#{name}(&block)
sass_callbacks ||= {}
_sass_callbacks[#{name.inspect}] ||= []) << block
run_#{name}(*args)
turn unless @_sass_callbacks
turn unless @_sass_callbacks[#{name.inspect}]
sass_callbacks[#{name.inspect}].each {|c| c[*args]}
ate :run_#{name}

end