[ruby-core:54925] [ruby-trunk - Bug #8393] A class who's parent class is in a module can go wrong if files are required in the wrong order

Issue #8393 has been updated by jeremyevans0 (Jeremy Evans).


This isn't a bug.  If you load animal.rb then dog.rb, at the point Bark::Dog is defined, Bark::Animal does not exist, so it finds Animal at the top level (standard ruby constant lookup).  If you want to force the behavior you desire, you should probably be specific about the superclass (class Dog < Bark::Animal) and require bark.rb at the top of dog.rb (to make sure Bark::Animal is defined before Bark::Dog).
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Bug #8393: A class who's parent class is in a module can go wrong if files are required in the wrong order
https://bugs.ruby-lang.org/issues/8393#change-39266

Author: eLobato (Daniel Lobato Garcia)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.0.0dev (2012-11-01 trunk 37411) [x86_64-linux]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


Hi,

I have found that inheritance is not done properly in a certain case. Let's say we have the following files:

--------------
animal.rb -

class Animal
  def bark
    puts 'fuck.'
  end
end
 

dog.rb -

module Bark
  class Dog < Animal
  end
end


bark.rb - 

module Bark
  class Animal
    def bark
      puts 'woof'
    end
  end
end
------------

If these files are required in that order (or any order where Bark::Animal is not required before Animal), Bark::Dog.new.bark will output "fuck.", showing the inheritance was done wrong, because in the case that there are two classes from which it can inherit (Animal and Bark::Animal), it should inherit from the class inside its module (Bark).

A workaround for this is defining Dog as Dog < Bark::Animal, that forces Dog to use the correct Animal class. 

I found this on the latest 1.8.7, 1.9.2, 1.9.3 and 2.0.0dev, both using rvm and without using it. I could not find information about this on the issue tracker or on Google.

In my opinion a way to fix this is to check when a file is required if any of our current files could inherit from something in a module of the file that is imported, but that looks like it can be complicated with nested modules, etc.. so I'm all ears for better design decisions. 

I would like to fix this myself as my first Ruby core contribution, but I was unsure if this is an actual bug. To me it looks like this behavior is totally unexpected, let me know if anything is wrong here.

Thanks!



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