Class Loader Weirdness | Rails 3.0.3

rubyonrails-talk
1

Hi guys,

I am stuck on, what i think is a class loader issue.

In my app/models directory i have the following files:

reductions/base.rb reductions/conversions_by_bucket.rb reductions/conversions_by_hour.rb reductions/impressions_by_hour.rb

(background -- i am using mongoid, and i use these files to manage mapReduce)

These classes only have class methods. In each of these classes I added the following method:

def self.hello   "hello" end

And checkout this weirdness from the rails console:

Reductions::ImpressionsByHour.hello

=> "hello"

Reductions::ConversionsByHour.hello

=> "hello"

Reductions::ImpressionsByBucket.hello

NoMethodError: undefined method `hello' for Reductions::ImpressionsByBucket:Class

BUT ...

require 'reductions/conversions_by_bucket.rb'

=> nil

Reductions::ConversionsByBucket.hello

=> "hello"

Soooooo weird!!! So why is reductions/conversions_by_bucket.rb not being loaded by the class loader?!

I am using rails 3.0.3

Thanks!!

2

I have the feeling the class-names are bit mismatched. what is the relation between Reductions::ConversionsByBucket and Reductions::ImpressionsByBucket ?

- Kristian

3

Yeah I thought that too -- but i have looked it over hundreds of times and can't find the mismatch. I have simplifed the classes to just have the hello method. And still have the same behavior. Here are the three classes

#app/models/reductions/impressions_by_hour.rb class Reductions::ImpressionsByHour   def self.hello     "hello"   end end

#app/models/reductions/conversions_by_hour.rb class Reductions::ConversionsByHour   def self.hello     "hello"   end end

#app/models/reductions/conversions_by_bucket.rb class Reductions::ConversionsByBucket   def self.hello     "hello"   end end

ls app/models/reductions/ base.rb conversions_by_bucket.rb conversions_by_hour.rb impressions_by_hour.rb unions.rb

The relationship between the classes is that they all perform map/ reduce methods. base.rb holds common code between them

I'm sure its something simple, but I am stumped!

-- Jonathan

4

I should add, that the class kind-of gets loaded, Checkout the following rails console sequence:

[2] > Reductions::ConversionsByBucket => Reductions::ConversionsByBucket [3] > Reductions::ConversionsByBucket.class => Class [4] > Reductions::ConversionsByBucket.hello NoMethodError: undefined method `hello' for Reductions::ConversionsByBucket:Class

[5] > require 'reductions/conversions_by_bucket.rb' => nil [6] > Reductions::ConversionsByBucket.hello => "hello"

5

I created a test app that highlights the problem:

https://github.com/jtushman/classloadingissue

6

Ok figured it out.

The AWS/SW gem overwrites Module#const_missing -- and messes with things if you class ends in 'Bucket'. Man, that was a great use of 6 hrs. No idea why it only happens when coupled with InheritedResources, but that clearly is the root of the problem.