from_directory_name

# File railties/lib/rails/gem_dependency.rb, line 32
    def self.from_directory_name(directory_name, load_spec=true)
      directory_name_parts = File.basename(directory_name).split('-')
      name    = directory_name_parts[0..-2].join('-')
      version = directory_name_parts.last
      result = self.new(name, :version => version)
      spec_filename = File.join(directory_name, '.specification')
      if load_spec
        raise "Missing specification file in #{File.dirname(spec_filename)}. Perhaps you need to do a 'rake gems:refresh_specs'?" unless File.exists?(spec_filename)
        spec = YAML::load_file(spec_filename)
        result.specification = spec
      end
      result
    rescue ArgumentError => e
      raise "Unable to determine gem name and version from '#{directory_name}'"
    end