snippet.rb

require 'yard'

module YardObject
  def source; yard_object.source end
  def docstring; yard_object.docstring end
  
  private
  
  def yard_object
    fname = source_location[0]
    @@file_cache ||= {}
    unless @@file_cache[fname]
      @@file_cache[fname] = true
      YARD.parse(fname)
    end
    @yard_object ||= YARD::Registry.at(owner.name + '#' + name.to_s)
  end
end

class Method; include YardObject end
class UnboundMethod; include YardObject end

class Foo
  # A docstring!
  def foo
  end
end

f = Foo.new
puts f.method(:foo).docstring
puts f.method(:foo).source
# A docstring!
# def foo
# end