gistfile1.rb

def require_or_install(path, gem_name = path, version = '> 0')
  require path
rescue LoadError
  require 'rubygems'
  require 'rubygems/user_interaction'
  require 'rubygems/dependency_installer'
  
  installer = Gem::DependencyInstaller.new
  installer.install gem_name, version

  Gem.refresh
  Gem.activate gem_name, version

  require path
end