如何在 运行 时间确定 Scala.js 和 JVM 的 Scala 版本？

Question

这个问题类似于How do I get the Scala version from within Scala itself?，只是我也想支持Scala.js。

我尝试了 util.Properties 方法。很遗憾，它在 Scala.js:

上不可用

https://scalafiddle.io/sf/dzNAhWB/0

ScalaFiddle.scala:-5: ERROR: There were linking errors
Referring to non-existent class java.util.jar.Attributes$Name
  called from scala.util.Properties$.()
  called from ScalaFiddle$.()
  exported to JavaScript with @JSExport
Referring to non-existent method java.util.Properties.load(java.io.InputStream)scala.Unit
  called from scala.util.PropertiesTrait.$$anonfun$scalaProps(java.util.Properties,java.io.InputStream)scala.Unit
  called from scala.util.Properties$.$$anonfun$scalaProps(java.util.Properties,java.io.InputStream)scala.Unit
  called from scala.util.PropertiesTrait.scalaProps()java.util.Properties
  called from scala.util.Properties$.scalaProps$lzycompute()java.util.Properties
  called from scala.util.Properties$.scalaProps()java.util.Properties
  called from scala.util.PropertiesTrait.scalaPropOrNone(java.lang.String)scala.Option
  called from scala.util.Properties$.scalaPropOrNone(java.lang.String)scala.Option
  called from scala.util.PropertiesTrait.$$init$()scala.Unit
  called from scala.util.Properties$.()
  called from ScalaFiddle$.()
  exported to JavaScript with @JSExport
involving instantiated classes:
  scala.util.Properties$
Referring to non-existent method java.lang.Class.getResourceAsStream(java.lang.String)java.io.InputStream
  called from scala.util.PropertiesTrait.scalaProps()java.util.Properties
  called from scala.util.Properties$.scalaProps$lzycompute()java.util.Properties
  called from scala.util.Properties$.scalaProps()java.util.Properties
  called from scala.util.PropertiesTrait.scalaPropOrNone(java.lang.String)scala.Option
  called from scala.util.Properties$.scalaPropOrNone(java.lang.String)scala.Option
  called from scala.util.PropertiesTrait.$$init$()scala.Unit
  called from scala.util.Properties$.()
  called from ScalaFiddle$.()
  exported to JavaScript with @JSExport
involving instantiated classes:
  scala.util.Properties$
Referring to non-existent method java.util.jar.Attributes$Name.(java.lang.String)
  called from scala.util.Properties$.()
  called from ScalaFiddle$.()
  exported to JavaScript with @JSExport

那么，如何在 运行 时为所有 Scala 后端确定 Scala 版本？

Answer 1

恐怕 Scala.js 一开始就没有办法做到这一点，更不用说独立于平台的解决方案了。

你可以做的是在你的构建工具（sbt？）中编写一个小任务，它将生成一个编码信息的小源文件。

例如，释义sbt documentation on source generators：

sourceGenerators in Compile += Def.task {
  val file = (sourceManaged in Compile).value / "scalaversion" / "ScalaVersion.scala"
  val scalaV = scalaVersion.value
  IO.write(file,
      s"""
        object ScalaVersion {
          val Full = "$scalaV"
        }
      """)
  Seq(file)
}.taskValue

然后您可以从您的代码中读取 ScalaVersion.Full。