From: Tom Werner <tom@...>
Date: 2006-07-15T02:24:36+09:00
Subject: Re: Preferred monkeypatching technique

Eric Hodel wrote:
> On Jul 13, 2006, at 5:04 PM, Tom Werner wrote:
>
>> Eric Hodel wrote:
>>> You just described subclasses:
>>
>> Well, the idea is that the 3rd party software is going to be using 
>> whatever classes it has always used, so just creating a subclass 
>> doesn't get me anywhere because the 3rd party app (i.e. Rails) 
>> doesn't give a hoot about my BigNozzleFiretruck.
>
> Can you give a concrete example where this takes place?
>

My specific purpose is to write a plugin for Rails that adds an option 
to each form field helper (the ones that create <input> tags) that 
specifies an appropriate class (since CSS attribute selector support is 
lacking in IE). So I'm using code like this:

module ActionView
  module Helpers
    module FormHelper

      # text
      alias_method :__classless_text_field, :text_field
      def text_field(object_name, method, options = {})
        __classless_text_field(object_name, method, 
options.merge({:class => (options[:class].to_s + ' text').strip}))
      end

    end
  end
end

Which works fine, but is subject to the infinite loop problem should 
someone else happen to alias in an identical manner. Even the 
*possibility* of this happening makes me feel dirty, and so I'm looking 
for a cleaner way to do it. As these helpers may be called quite often, 
a solution that doesn't badly impact performance is essential. There are 
some other ideas on this thread that I still need to investigate, I was 
just curious if there's some standard practice for this sort of thing. 
Thanks!!

Tom

-- 
Tom Werner
Helmets to Hardhats
Software Developer
tom@helmetstohardhats.org
www.helmetstohardhats.org