SBT including the version number in a program

Question

I want a program I\'m building to be able to report its own version at runtime (e.g. scala myprog.jar --version). Traditionally in a maven project, I\'d use res

Answer 1

In general, without any plugins, you can do something like this:

sourceGenerators in Compile += Def.task {
  val file = (sourceManaged in Compile).value / "foo" / "bar" / "BuildInfo.scala"

  IO.write(
    file,
    s"""package foo.bar
       |object BuildInfo {
       |  val Version = "${version.value}"
       |}""".stripMargin
  )

  Seq(file)
}.taskValue

And then do with foo.bar.BuildInfo.Version constant whatever you like.

Or more general:

def generateBuildInfo(packageName: String,
                      objectName: String = "BuildInfo"): Setting[_] =
  sourceGenerators in Compile += Def.task {
    val file =
      packageName
        .split('.')
        .foldLeft((sourceManaged in Compile).value)(_ / _) / s"$objectName.scala"

    IO.write(
      file,
      s"""package $packageName
         |object $objectName {
         |  val Version = "${version.value}"
         |}""".stripMargin
    )

    Seq(file)
  }.taskValue

Example:

settings(generateBuildInfo("foo.bar"))

You can even change this to pass object properties as a Map[String, String] and generate the object appropriately.