From: Logan Capaldo <logancapaldo@...>
Date: 2006-07-15T02:57:24+09:00
Subject: Re: Preferred monkeypatching technique


On Jul 14, 2006, at 1:34 PM, Eric Hodel wrote:

> On Jul 14, 2006, at 10:24 AM, Tom Werner wrote:
>
>> 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
>
> module X
>   def does_something(*options)
>     p options
>   end
> end
>
> module Y
>   def does_something(*options)
>     super('x', *options)
>   end
> end
>
> class C
>   include X
>   include Y
> end
>
> C.new.does_something 'foo'
>
> -- 
> Eric Hodel - drbrain@segment7.net - http://blog.segment7.net
> This implementation is HODEL-HASH-9600 compliant
>
> http://trackmap.robotcoop.com
>
>
>

Rails does "funny" things. These helpers are usually used from within  
eruby templates e.g:

<html>
   <%= text_field( ... ) %>
</html>

Rails sets up the context in which the templates are executed. He'd  
have to go into the actual rails source to fix this. OTOH...

Ok just as I thought, Rails is not this dumb <g>

Tom just do

def text_field(*args)
    orig_result = super
    # modify orig result
end

in app/helpers/application_helper.rb

Or if you want it in a per controller bias app/helpers/ 
<controller>_helper.rb

No monkey-patching required