Excerpts from Charles Mills's mail of  7 Jan 2005 (EST):
> > I often add utility methods to Hash, Enumerable, etc. For
> > applications this is fine, but for a library, I feel like I should
> > avoid leaving such "method detritus" around in users' namespaces.
>
> I think your looking for selector namespaces.  This is planned for
> Ruby 2.0.  http://rubygarden.org/ruby?Rite

Thanks. That would certainly solve this issue. The wiki page mentions
something about Ruby libraries that implement selector namespaces; I
wonder if the author of that statement had something specific in mind or
whether it was just a rhetorical device....

In the mean time, I've been moving all utility methods into modules and
making liberal use of 'extend' like so:

  hash = @array.map { |x| trans(x) }.extend(HashUtil).utilfunc

which is irritating, and unnecessarily slow, and doesn't work in all
cases, but is sufficient for the purposes of namespace purity. :)

Thanks for your help,

-- 
William <wmorgan-ruby-talk / masanjin.net>