gistfile1.txt

class R
  def initialize
    @methods = {}
  end
  
  def method(name)
    @methods[name]
  end
  
  def declare(name, &blk)
    @methods[name] = blk
  end
end

class C
  def initialize(r, x)
    @r = r
    @x = x
  end
  
  def method_missing(meth, *args)
    instance_exec(*args, &@r.method(meth))
  end
end

r = R.new
r.declare(:x){|a| puts a + @x}
c = C.new(r, 2)
c.x(5)