为什么在运行时无法访问用 Scala 编写的注释？
Why annotations written in Scala are not accessible at runtime?
我在 scalatest 文档中看到一个声明：
It must be defined in Java instead of Scala so it will be accessible at runtime.
这很奇怪，因为我的印象是 Scala 注释比它的 Java 注释更强大。为什么缺少此功能？有计划加回去吗？
没有已知的计划在运行时保留 Scala 支持注释（这个问题已经知道一段时间了，但正如 this page 所说，它不会被修复）。
Lukas Rytz, a Scala committer, explained on a post 在 scala-language 邮件列表中：
It's definitely non-trivial. Java annotations have specific
representation in bytecode [...],
which would require changes to Scala's bytecode generator.
Also the language of java annotations is quite special, different from
the rest of the Java language [...], so one would need to define
how this can be represented in a Scala class.
我在 scalatest 文档中看到一个声明：
It must be defined in Java instead of Scala so it will be accessible at runtime.
这很奇怪，因为我的印象是 Scala 注释比它的 Java 注释更强大。为什么缺少此功能？有计划加回去吗？
没有已知的计划在运行时保留 Scala 支持注释（这个问题已经知道一段时间了，但正如 this page 所说，它不会被修复）。
Lukas Rytz, a Scala committer, explained on a post 在 scala-language 邮件列表中：
It's definitely non-trivial. Java annotations have specific representation in bytecode [...], which would require changes to Scala's bytecode generator.
Also the language of java annotations is quite special, different from the rest of the Java language [...], so one would need to define how this can be represented in a Scala class.