## controllers/foo_controller.rb
class FooController < ApplicationController
  def index
  end
  
  def foo
    render :update do |p|
      p.insert_html :before, :log, hidden
    end
  end
  
  # This method is not available to the render(:update) block above, for reasons that defy all knowledge!
  def hidden
    "I am in FooController#hidden"
  end
end

## views/foo/index.rhtml
<ul>
  <li><%= link_to_remote 'do it', :url => {:action => :foo} %></li>
</ul>

<div id="log"></div>

## Error
Processing FooController#foo (for 127.0.0.1 at 2007-07-02 16:13:16) [POST]
  Session ID: d68d417ce47c8c8565167723981dbdf2
  Parameters: {"action"=>"foo", "controller"=>"foo"}


NameError (undefined local variable or method `hidden' for #<#<Class:0x31a239c>:0x31a2374>):
    .//app/controllers/foo_controller.rb:7:in `__bind_1183407196_828125'