From: Daniel Schierbeck <daniel.schierbeck@...>
Date: 2006-07-15T05:05:05+09:00
Subject: Re: Preferred monkeypatching technique

Tom Werner wrote:
> Allow me to present a scenario:
> 
> class Firetruck
>    def put_out_fire(options = {})
>       # code
>    end
> end
> 
> Pretend Firetruck is in a 3rd party application (like Rails) that is 
> happy to allow plugins to modify core code. Now, let's say I want to 
> write some code that always adds a certain attribute to the options 
> hash. I could do this:
> 
> class Firetruck
>    alias_method :__old_put_out_fire, :put_out_fire
>    def put_out_fire(options = {})
>       __old_put_out_fire(options.merge({:nozzle => :big}))
>    end
> end
> 
> Which works just fine until someone else comes up with a plugin that 
> wants to modify the same method (doing something similar to me) and just 
> so happens to also use :__old_put_out_fire as THEIR alias. Now we've got 
> my plugin's method as the alias calling itself, which leads to, you 
> know, badness.
> 
> So I'm wondering if there's a better way. Perhaps some way to turn 
> Firetruck into an ancestor of itself, so to speak, so that my plugin 
> would create a new Firetruck class, pushing the old Firetruck backward 
> in the chain and allowing me to call super instead and preventing 
> alias_method explosions. Or would that just end up causing more havoc?

Not a solution, but:

   <http://rcrchive.net/rcr/show/321>

   cut MyCut < Firetruck
     def put_out_fire(options = {})
       super(options.merge(:nozzle => :big))
     end
   end

(Trans, can I omit the `MyCut <' part?)


Cheers,
Daniel