From: Intransition <transfire@...>
Date: 2009-11-24T09:09:42+09:00
Subject: Re: RubyGems current load paths



On Nov 23, 5:38 pm, Eric Hodel <drbr...@segment7.net> wrote:
> On Nov 20, 2009, at 08:40, Intransition wrote:
>
> > I need to get a list of the "current" gem load paths. I learned that I
> > can get a list of all the latest load paths via:
>
> >  Gem.latest_load_paths
>
> > which is great. But lets say I specify an older version of a lib, eg:
>
> >  gem "RubyInline", "= 3.7.0"
>
> > Gem.latest_load_paths doesn't change. How can I get a list of latest
> > load paths but adjusted to reflect any specified gem versions?
>
> Gem.latest_load_paths works for all installed gems, even if they're  
> not activated.  You'll need to use Gem::Specification#full_gem_path  
> and Gem::Specification#require_path.
>
> Needing to know where the gem lives is a sign that you're doing  
> something wrong though.

I'm doing a little meta-programming in this case -- I've created a
function to find "plugins". So I need to search through the $LOAD_PATH
and Gems. But I'm all ears if there is another way to do it. Here's
the code:

  # = Plugin Handler
  #
  # Find plugins across various library managers.
  #
  module Plugin

    extend self

    DIRECTORY = 'plugin'

    # Find plugins, searching through standard $LOAD_PATH,
    # Roll Libraries and RubyGems.
    #
    # Provide a +match+ file glob to find plugins.
    #
    #   Plugins.find('syckle/*')
    #
    def find(match)
      plugins = []

      # Standard $LOAD_PATH
      $LOAD_PATH.uniq.each do |path|
        list = Dir.glob(File.join(path, DIRECTORY, match))
        #dirs = dirs.select{ |d| File.directory?(d) }
        list = list.map{ |d| d.chomp('/') }
        plugins.concat(list)
      end

      # ROLL (load latest or current versions only)
      if defined?(::Roll)
        ::Roll::Library.ledger.each do |name, lib|
          lib = lib.sort.first if Array===lib
          lib.load_path.each do |path|
            find = File.join(lib.location, path, DIRECTORY, match)
            list = Dir.glob(find)
            list = list.map{ |d| d.chomp('/') }
            plugins.concat(list)
          end
        end
      end

      # RubyGems (load latest versions only)
      # TODO: need current versions
      if defined?(::Gem)
        Gem.latest_load_paths do |path|
          list = Dir.glob(File.join(path, DIRECTORY, match))
          list = list.map{ |d| d.chomp('/') }
          plugins.concat(list)
        end
      end

      plugins
    end

    # Shortcut for #find.
    #
    #   Plugins['syckle/*']
    #
    alias_method :[], :find

  end

Also, I wonder how Ruby 1.9 might effect this. Are the latest gem
paths added to the $LOAD_PATH by default in 1.9?