proxy.rb

class BlankSlate
   instance_methods.each { |m| undef_method m unless m =~ /^__/ }
end

class MyProxy < BlankSlate
  def initialize(obj, &proc)
    @proc = proc
    @obj = obj
  end

  def method_missing(sym, *args, &block)
    @proc.call(@obj,sym, *args)
    @obj.__send__(sym, *args, &block)
  end
end