问题描述
当反思仍处于初期阶段时，在 Scala 2.10.0 里程碑的日子里，我提出了一个问题我可以用它来查看 REPL 中的代码片段树吗?优秀的答案比我问的更进一步，并展示了如何使用它们来解析和评估树，所以我继续尝试在我今天正在进行的一个小项目中使用它.
Back when reflection was still incipient, on the days of Scala 2.10.0 milestones, I asked a question about how could I use it to see the trees of code snippets from REPL. The excellent answer went further than I asked, and showed how they can be used to parse and evaluate trees as well, so I went ahead and tried to use that on a little project I had going on today.
不幸的是，以这种方式解析和评估的代码似乎没有看到任何 REPL 定义:
Unfortunately, code parsed and evaluated that way doesn't seem to see any REPL definition:
scala> val x = 1
x: Int = 1
scala> import scala.tools.reflect.ToolBox
import scala.tools.reflect.ToolBox
scala> val tb = scala.reflect.runtime.universe.runtimeMirror(
getClass.getClassLoader).mkToolBox()
tb: scala.tools.reflect.ToolBox[reflect.runtime.universe.type] = ...
scala> tb.eval(tb.parse("x"))
scala.tools.reflect.ToolBoxError: reflective compilation has failed:
not found: value x
有没有办法让它识别 REPL 上的定义?
Is there a way to get it to recognize definitions made on REPL?
推荐答案
最近我深入研究了 repl，试图让它支持类型宏，所以我有能力解释为什么它不起作用.下一步是让它工作:)
Recently I dug into repl, when trying to make it support type macros, so I'm well equipped to explain why it doesn't work. Getting it to work would be the next step :)
我知道您知道输入到 repl 中的每个片段在编译之前都会被包装到一些样板中.因此， x 最终成为包中嵌套嵌套对象中的字段，名称很奇怪.
I know that you know that every snippet entered into repl gets wrapped into some boilerplate before being compiled. Therefore that x ends up being a field in a nested-nested-nested object in a package with a weird name.
显然，repl 会跟踪所有定义的符号，然后将必要的导入与其生成的样板一起注入.因此后续行可以看到 x 不合格.相比之下，工具箱只是重用了 repl 的类加载器，但不对导入做任何事情，因此失败了.
Apparently, repl keeps track of all defined symbols and then injects the necessary imports along with the boilerplate it generates. Therefore subsequent lines can see that x unqualified. To the contrast, toolboxes simply reuse repl's classloader, but don't do anything about the imports, hence the failure.
一种解决方法是以某种方式获取一个表示 repl 的对象，向它询问已定义的符号，然后将相应的导入生成到您提供给工具箱的代码中.如果您提交工单，我会在 2.10.1 代码冻结疯狂结束后(据说是本周末)尝试编写解决方法.
A workaround would be to somehow get to an object representing a repl, ask it about defined symbols and then generate corresponding imports into the code that you feed to a toolbox. If you file a ticket, I'll try to code up a workaround after the 2.10.1 code freeze madness ends (supposedly, end of this week).
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