require_outer_gem.rb

module Kernel
  def require_outer_gem(path)
    gem_path = "#{Gem.path.first}/gems"
    extract_gem_name = ->(gems_paths){ gems_paths.map{|s| s[/gems\/([^\/]+)\/lib$/, 1] }.compact }

    outer_gems = extract_gem_name[Dir["#{gem_path}/*/lib"]] - extract_gem_name[$LOAD_PATH]
    outer_gems = outer_gems.lazy
                           .map{|s| s.rpartition('-') }
                           .map{|gem_name, _, version| [gem_name, version] }
                           .sort_by{|_, v| Gem::Version.new(v) } # 多版本的話選最新版號
                           .reverse
                           .to_h
                           .to_a
                           .map{|s| s.join('-') }

    origin_load_paths = $LOAD_PATH.clone
    begin
      $LOAD_PATH.concat(outer_gems.map{|s| "#{gem_path}/#{s}/lib" })
      require(path)
    ensure
      $LOAD_PATH.clear
      $LOAD_PATH.concat(origin_load_paths) # 還原原本的 $LOAD_PATH
    end
  end
end