From: Rick DeNatale <rick.denatale@...>
Date: 2010-07-31T23:55:35+09:00
Subject: Re: Problem with a lambda not executing immediately

On Fri, Jul 30, 2010 at 5:40 AM, Fernando Perez <pedrolito@lavache.com> wrote:
>> Given that the key in the hash is
>> :processors (in plural) I would assume that the value should be an
>> array of processors.
>
> Yes style.processors is expected to be an array
>
>> So, even if you only have one lambda, can you try this:
>>
>> class Asset < ActiveRecord::Base
>>   has_attached_file :data, :styles => {
>>     :theora => [:format => :ogv, :processors => [lambda {|a| a.video?
>> ? [:video_converter] : []}]}]
>> }
>
> Unfortunately it doesn't work, as when the lambda gets executed, the "a"
> object it receives is not the not it expects: "wrong constant name
> passed".

I suspect that you would get better answers on the rails forum since
paperclip is better known there than in the general Ruby community.
but..

First, the :processors option isn't supposed to be part of the :style hash

  has_attached_file :date,
                             :styles => {:theora => {:format => :ogv},
                             :processors => [
                                    # something goes here
                             ]


Now it appears you are trying to use a feature of paperclip which
doesn't seem to be documented, normally the value for the :processors
option is just an array of symbols which are converted to an instance
of a subclass of Paperclip::Processor.  But from reading the code it
appears that you can also do:

class Asset < ActiveRecord::Base

  has_attached_file :date,
                             :styles => {:theora => {:format => :ogv},
                             :processors => lambda { | asset |  # the
instance of the Asset model

asset.video? ? [:video_converter] : []
                                                    }
end

I'd probably refactor this a bit:

class Asset < ActiveRecord::Base

  has_attached_file :date,
                             :styles => {:theora => {:format => :ogv},
                             :processors => lambda { | asset |
asset.processors }

  def processors
     self.video? ? [:video_converter] : []
   end
end


I've tested none of this so take it with the appropriate grain of salt.

-- 
Rick DeNatale

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