From: Charles Oliver Nutter <charles.nutter@...>
Date: 2008-12-23T02:14:52+09:00
Subject: [ruby-core:20798] Re: use of require thread safety

Paul Brannan wrote:
> On Mon, Dec 22, 2008 at 03:05:07AM +0900, Charles Oliver Nutter wrote:
>> Two threads requiring the separate files at the same time will deadlock.  
>> Of course this is contrived, but there are circular requires fairly  
>> often in applications.
> 
> What applications use circular requires?
> 
> I don't think circular dependencies are a good idea in general, though
> Ruby shouldn't break if someone tries.

It's not so much that they intend to be circular; more it's that many 
files re-require all resources they expect to need, which over time can 
result in circular dependencies (if every script requires everything it 
things it needs, it's almost assured a few of those will have reverse 
dependencies back).

file_one.rb

require 'file_two'
require 'file_three'
require 'file_four'

module Foo ....

file_three.rb

# I know I need file_one to be loaded so module Foo is available...
require 'file_one'

class Blah; include Foo ...

- Charlie