From: Simon Strandgaard <neoneye@...>
Date: 2004-03-24T02:34:30+09:00
Subject: Re: rubygems working with non-gems libs?

I have refined the gem-require hack a bit more.

Place the 'gemrequirehack.rb' in rubys path.

Add the following line to your tcshrc:
setenv RUBYOPT "rgemrequirehack"


The source-code is here:


server> expand -t2 gemrequirehack.rb 
module Kernel
  alias old_require require 
  def require(filename, version=nil)
    ok = nil
    begin
      ok = old_require(filename)
      if version
        $stderr.puts <<-MSG.gsub(/^\s*/, "") 
        Hack which loads "rubygems" when Ruby starts up, has
        been supplied a version string (#{version}), however
        the required file (#{filename}) is not a rubygem, and
        thus doesn't take a version number.
        The version number has therefore been ignored.
        MSG
      end
    rescue LoadError => old_e
      begin
        old_require("rubygems")
      rescue LoadError
        $stderr.puts <<-MSG.gsub(/^\s*/, "")
        Hack which loads "rubygems" when Ruby starts up, failed
        to find "rubygems". You may want to either install
        "rubygems" or remove this hack from the RUBYOPT envvar.
        MSG
        raise old_e
      end
      begin
        ok = require_gem(filename, version || "> 0.0.0")
      rescue LoadError => gem_e
        raise gem_e 
        #raise old_e 
      end
    end
    ok
  end
end # module Kernel
server>


There is a small testsuite here:

server> expand -t2 test_gemrequirehack.rb 
# purpose:
# exercise if rubygems require hack is working.
#
# depends on:
# * rubygems
# * progressbar = 0.0.3, shipped with rubygems
require 'test/unit'
require 'stringio'
require 'gemrequirehack'

class TestGemRequireHack < Test::Unit::TestCase
  def capture_stderr(&block)
    e = StringIO.new
    $stderr = e
    block.call
    return e.string
  ensure
    $stderr = STDERR
  end
  def test_loaderror
    e = assert_raise(LoadError) do
      require 'nonexisting'
    end
    assert_match(/not find RubyGem nonexisting/, e.message)
  end
  def test_1_old_require_normal
    ok = require 'observer'      # is shipped with Ruby
    assert_equal(true, ok)  # first time we load it
    ok = require 'observer'     
    assert_equal(false, ok) # second time.. its already loaded
  end
  def test_2_old_require_version
    warning = capture_stderr do
      require 'observer', '> 6.6.6'  # shipped with Ruby, but has no version
    end
    assert_match(/version number has therefore been ignored/, warning)
  end
  def test_1_gem_require_failed
    path = $:.clone
    $:.clear
    output = capture_stderr do
      e = assert_raise(LoadError) do
        require 'progressbar'   # is shipped with rubygems
      end
      assert_match(/^No such file to load -- progressbar$/, e.message)
    end
    assert_match(/Hack/, output)
  ensure
    $:.concat(path)
  end
  def test_2_gem_require_version
    e = assert_raise(LoadError) do
      require 'progressbar', '>= 0.0.4'    # 0.0.3 is shipped with rubygems
    end
    assert_match(/version error: progressbar\(0.0.3 not >= 0.0.4\)/, e.message)
  end
  def test_3_gem_require_normal
    ok = require 'progressbar'   # is shipped with rubygems
    assert_equal(true, ok)  # first time we load it
    ok = require 'progressbar'
    assert_equal(false, ok) # second time.. its already loaded
  end
end

if $0 == __FILE__
  require 'test/unit/ui/console/testrunner'
  Test::Unit::UI::Console::TestRunner.run(TestGemRequireHack)
end
server>


When running the testsuite it should output:

server> ruby test_gemrequirehack.rb
Loaded suite TestGemRequireHack
Started
.......
Finished in 0.085952 seconds.

6 tests, 12 assertions, 0 failures, 0 errors
server>


--
Simon Strandgaard