SBT项目中的条件设置

Question

我在 SBT (1.1.6) 中有一个多模块项目。

我的示例模块定义：

lazy val `example` = (project in file("example"))
  .settings(
    scalaVersion := "2.11.12",
    crossScalaVersions := Seq("2.10.7", "2.11.12"),
    libraryDependencies ++= Seq( ... )
  )

现在我的意图是禁用2.11 jar 的发布，设置：

lazy val dontPublish: Seq[Def.Setting[_]] = Seq(
  publish := {},
  publishLocal := {},
  publishM2 := {},
  publishArtifact := false,
  publishTo := None
).flatten

我可以阻止所有的情况，所以我希望一些简单的事情，比如：

lazy val `example` = (project in file("example"))
  .settings(
    scalaVersion := "2.11.12",
    crossScalaVersions := Seq("2.10.7", "2.11.12"),
    (if (scalaBinaryVersion.value == "2.11") dontPublish else Seq.empty),
    libraryDependencies ++= Seq( ... )
  )

可以工作，但是...我收到一个错误：

/path/build.sbt:371: error: `value` can only be used within a task or setting macro, such as :=, +=, ++=, Def.task, or Def.setting.
(if (scalaBinaryVersion.value == "2.11") dontPublish else Seq.empty).flatten,
^
[error] sbt.compiler.EvalException: Type error in expression

---

问题：

如何根据条件（例如，Scala 版本）添加设置？

Answer 1

我最终适应了https://gist.github.com/joescii/4431cb2185eddb699dfb79b9c910e333 给SBT 1.1.6

我的解决方案：

val neverPublish = dontPublishIf(scalaVersion)(_ => true)

def dontPublishIf[P](key: SettingKey[P])(p: P => Boolean): Seq[Def.Setting[_]] = {
  Seq(
    //@formatter:off
    skip in publish      := p(key.value),
    skip in publishLocal := p(key.value),
    skip in publishM2    := p(key.value)
    //@formatter:on
  ) ++ dontPublishAssemblyIf(key)(p)
}

def isAssemblyArtifact(a: Artifact): Boolean =
  a.classifier.contains("assembly")

def dontPublishAssemblyIf[P](key: SettingKey[P])(p: P => Boolean): Seq[Def.Setting[_]] = {
  Seq(
    // remove added assembly artifacts and publishTasks
    //@formatter:off
    artifacts         := artifacts        .value.filterNot {       a     => p(key.value) && isAssemblyArtifact(a) },
    packagedArtifacts := packagedArtifacts.value.filterNot { case (a, _) => p(key.value) && isAssemblyArtifact(a) }
    //@formatter:on
  )
}

我很惊讶 SBT 真的这么难用，但在这次冒险中，我对它的内部有了更多的了解。

如果有人遇到类似问题，我只是发布。

Answer 2

无论如何我都不是 SBT 专家，但我最近遇到了一个类似的问题，我通过将所有不是很简单的语句从 build.sbt 移到 project/MySettings.scala 来解决这个问题。 .sbt 文件的解析规则不断让我感到困惑，但在 .scala 文件中它只是常规的 scala。所以你会有类似的东西

object MySettings {
  val dontPublish: Seq[Def.Setting[_]] = Seq(
    publish := {},
    publishLocal := {},
    publishM2 := {},
    publishArtifact := false,
    publishTo := None
  ).flatten

  val maybeDontPublish = if (scalaBinaryVersion.value == "2.11") dontPublish else Seq.empty
}

然后在你的build.sbt:

lazy val `example` = (project in file("example"))
  .settings(
    scalaVersion := "2.11.12",
    crossScalaVersions := Seq("2.10.7", "2.11.12"),
    MySettings.maybeDontPublish,
    libraryDependencies ++= Seq( ... )
  )

您可能还需要将scalaVersion 和crossScalaVersion 拉到MySettings.scala 中，我不完全确定，因为它们是半魔法的。或者可能将MySettings.maybeDontPublish 更改为def maybeDontPublish(scalaVersion: String): Seq[Setting]

Answer 3

如错误所示，您只能访问任务或设置宏中的value。你可以通过添加设置skip in publish := scalaBinaryVersion.value == "2.11"来完成你想要的。