From: Stefano Crocco <stefano.crocco@...>
Date: 2010-12-14T17:12:57+09:00
Subject: Re: Conflicting definitions between ActiveRecord and QT

On Tuesday 14 December 2010 13:19:29 Emil Macarie wrote:
> I am somewhat of a Ruby newbie, so if this question is in the wrong
> forum please let me know.
> 
>   The specific problem I have is ActiveRecord + QT, but the problem is
> generic and I am asking how to solve similar issues as well.
> 
>   So I started experimenting with Ruby a bit and I was trying to play
> with ActiveRecord.
>   My first thought was to play with ActiveRecord and understand it
> separate from all the Rails infrastructure.
>   I install ruby 1.9.1, ruby qtbindings, and read up some qt tutorials
> and I am ready to rock.
> 
>   Even the simplest program throws an error when I try to mix qt and
> active record.
> 
>   The following lines do not work.
> 
> require 'active_record'
> require 'Qt4'
> require 'sqlite3'
> 
> class Review < ActiveRecord::Base
> end
> 
>   I get the error:
> /usr/local/rvm/gems/ruby-1.9.2-p0/gems/qtbindings-4.6.3.2/lib/Qt/qtruby4.rb:
> 3164:in `constants': wrong number of arguments (1 for 0) (ArgumentError)
>         from
> /usr/local/rvm/gems/ruby-1.9.2-p0/gems/activesupport-3.0.3/lib/active_suppor
> t/core_ext/module/introspection.rb:79:in `local_constants'
> 
> 
>   Basically there is a constants defined for Module in qtruby4.rb as
> well as introspection.rb
>   How can I go about resolving such a conflict.  As far as I can see
> there are no modules used, just on giant C like global namespace.  Is
> there any way I can separate qt and active record by namespace ?
> 
>   Any suggestions for further research would be very helpful.
> 
>   Thanks !

In ruby 1.8, Module#constants takes no arguments and qt-ruby redefines it in 
the same way. However, in ruby 1.9, Module#constants takes one argument (which 
is why activesupport calls it with one), but qt-ruby doesn't take this into 
account when redefining it. I'd say this is a bug in qt-ruby and will report 
it to the developers. In the meantime, I think you can solve your issue 
redefining it yourself before requiring activesupport:

require 'activesupport'
require 'Qt4'

class Module

  alias_method :constants_defined_by_qt, :constants
  def constants inherit=true
    constants_defined_by_qt
  end

end

I hope this helps

Stefano