From: Jim Freeze <jim@...>
Date: 2005-03-04T14:06:08+09:00
Subject: Re: ruby gems, and the require problem (was Re: RAA Status & b)

* Sam Roberts <sroberts@uniserve.com> [2005-03-04 09:48:04 +0900]:

> Or say I have:
> 
>   A - v 3, 4, 5 installed
>   B - a script I downloaded and run
>   B requires X, which needs A with version >=3
>     -> I'll get version 5, right/
>   B requires Y, which needs A with version <= 4
>     -> It will die, right?
> 
> So, now I trouble shoot... and uninstall A version 5. How did rubygems
> help me? I could have done this without ruby gems!

:>V

For singular library version requirements, gems works fine.
For multiple library version requirements, gems provides the
capability to load different versions of a library, but still 
has the problem of the classes having the same names.
I think this could be solved elegantly with selector namespaces,
but they aren't here yet.

<thinking out loud>
Hmm, could a little discipline in module definition and usage help
out here?.

module V123
  class Fred
  end
end

module V234
  class Fred
end

versions = []
versions << require('fred', '123')  # returns ref to module V123
versions << require('fred', '234')  # returns ref to module V234

versions.each { |v| v::Fred.new }

-- 
Jim Freeze
Code Red. Code Ruby