我希望加载一些库，让它们做一些工作，然后执行与 require 相反的操作，以避免以后出现兼容性错误。我不想转储到文件并重新启动 shell，因为创建的对象(例如 data)可以由我的其他库很好地处理，只是不存在早期我要卸载的那些。

有人有任何建议或知道这是否可行吗？ A conversation from 2006除了“看起来 Webrick 设法以某种方式做到这一点”之外，没有得出太多结论。

有问题的库是 Google_drive and Nokogiri (电子表格处理库 Roo 依赖 Google_drive 进行在线电子表格读/写，如该链接所述)。

最佳答案

正如@Alex 所说，您可以使用 Kernel#fork创建一个新的 ruby​​ 进程，您将在其中 require 您的库。新的 fork 进程将有权访问父进程中加载​​的数据:

def talk(msg)
  # this will allow us to see which process is
  # talking
  puts "#{Process.pid}: #{msg}"
end

# this data was loaded on the parent process
# and will be use in the child (and in the parent)
this_is_data = ["a", "b", "c"]

talk "I'm the father process, and I see #{this_is_data}"

# this will create a new ruby process
fork{
  talk "I'm another process, and I also see #{this_is_data}"
  talk "But when I change `this_is_data`, a new copy of it is created"
  this_is_data << "d"
  talk "My own #{this_is_data}"
}

# let's wait and give a chance to the child process
# finishes before the parent
sleep 3

talk "Now, in the father again, data is: #{this_is_data}"

这个执行的结果在你的机器上会有所不同，Process.id 会返回不同的值，但它会像这样:

23520: I'm the father process, and I see ["a", "b", "c"]
23551: I'm another process, and I also see ["a", "b", "c"]
23551: But when I change `this_is_data`, a new copy of it is created
23551: My own ["a", "b", "c", "d"]
23520: Now, in the father again, data is: ["a", "b", "c"]

这很好! fork 创建的每个进程都是一个操作系统。级别进程并在它自己的内存空间中运行。

要以某种方式管理通过加载文件创建的全局变量，您可以做的另一件事是将 require 的使用替换为 load。这种方法并不能解决已经指出的所有问题，但确实可以提供帮助。请参阅以下规范:

require "minitest/autorun"

describe "Loading files inside a scope" do

  def create_lib_file(version)
    libfile = <<CODE
      class MyLibrary#{version}
        VERSION = "0.0.#{version}"
      end

      class String
        def omg_danger!
        end
      end

      puts "loaded \#{MyLibrary#{version}::VERSION}"
    CODE

    File.write("my_library.rb", libfile)
  end

  after do
    File.delete("my_library.rb") if File.exists?("my_library.rb")
  end

  describe "loading with require" do
    it "sees the MyLibrary definition" do
      create_lib_file("1")
      require_relative "my_library.rb"
      MyLibrary1::VERSION.must_be :==, "0.0.1"
      "".respond_to?(:omg_danger!).must_be :==, true
    end
  end

  describe "loading with #load " do
    describe "without wrapping" do
      it "sees the MyLibrary definition" do
        create_lib_file("2")
        load "my_library.rb"
        MyLibrary2::VERSION.must_be :==, "0.0.2"
        "".respond_to?(:omg_danger!).must_be :==, true
      end
    end

    describe "using anonymous module wraping" do
      it "doesn't sees MyLibrary definition" do
        create_lib_file("3")
        load "my_library.rb", true
        ->{ MyLibrary3 }.must_raise NameError
        "".respond_to?(:omg_danger!).must_be :==, false
      end
    end
  end
end

以及执行结果:

Run options: --seed 16453

# Running tests:

loaded 0.0.3
.loaded 0.0.2
.loaded 0.0.1
.

Finished tests in 0.004707s, 637.3486 tests/s, 1274.6973 assertions/s.

3 tests, 6 assertions, 0 failures, 0 errors, 0 skips

关于ruby - 是否有可能 'unload' ('un-require' ) 一个 Ruby 库？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19753060/