From: TRANS <transfire@...>
Date: 2005-09-27T05:55:24+09:00
Subject: Require Namepaces and RubyGems' effect on LoadPath problem

I've added namespaces to require. Works like this:

  $LOAD_SPACE[ 'myspace' ] = [ 'a/path', 'another/path' ]

  require 'myspace:script.rb'

The load spaces are File.join'd with the entries in $LOAD_PATH,
$LOAD_PATH is unshifted with those entries and the built-in #require
is called. When complete it removes those namespace paths. The key
thing to keep in mind here: this allows for *relative* paths within
the context of the namespace require. For example:

  $LOAD_SPACE[ 'tim' ] = [ 'tim/path' ]

  require 'tim:file.rb'

tim/path/file.rb:

  require 'file2.rb'

file2.rb is located at tim/path/file2.rb. The above require works fine
w/o using 'tim/path/file2.rb' b/c the path defined by the namespace
has been temporarily placed in $LOAD_PATH in the first require call.

So this works great in itself. BUT Gems will add any matches it finds
*permanently* to the $LOAD_PATH. Hence if I distribute this via Gems
I'm pretty sure this will get all messed up, and won't properly remove
what this only *temporarily* adds.

Suggestions?

Below is the code.

T.


# This module allows kernel methods to be overridden
# in a OOP fashion. SubKernel is appended to Object,
# allowing it to slip in prior to the original Kernel.
#
# In also adds a new #require sub-method that allows for
# namespaces.
#
module SubKernel
  $LOAD_SPACE = {}

  # A new #require sub-method that allows for namespaces.
  def require( fpath )
    success = false
    name, space = fpath.split(':').reverse
    if space and $LOAD_SPACE.key?( space )
      load_path = $LOAD_PATH.dup
      begin
        search_path = []
        $LOAD_PATH.each { |lp|
          $LOAD_SPACE[ space ].each { |ls|
            if File.directory?( File.join( lp, ls ) )
              search_path << File.join( lp, ls )
            end
          }
        }
        $LOAD_PATH.replace(search_path | $LOAD_PATH)
        success = super( name )
      ensure
        $LOAD_PATH.replace($LOAD_PATH - search_path)
        #$LOAD_PATH.replace(load_path)  # Thwart Gems?
      end
    else
      success = super( fpath )
    end
    success
  end

end

class Object
  include SubKernel
end