Quoting Mauricio Fern?ndez <batsman.geo / yahoo.com>:

> > The following code worked in 1.6.8:
> > require 'Mymodule'
> > include Mymodule
> 
> This includes Mymodule in Object (and hence in every Ruby object), are
> you sure you want to do that?

This is interesting question. In fact I experienced the error in one of my 
FXRuby applications where I add a method to the existing class. AFAIK lot of 
FXRuby scripts (including samples) starts with

require 'fox'
include Fox 

Now you have all the Fox classes handy in the common namespace.

Does this mean a possible performance penalty if every object "knows" about all 
definitions from the Fox module? Should this be considered as a bad programming 
practice?

The right Ruby way should probably be

require 'fox'

class MyApp
  include Fox
  ...
  ...
end

which does not generate the error.
 
Dalibor Sramek