scala - 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，设置如下:

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

我可以阻止所有情况，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...我得到一个错误:

/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

我最终改编了 https://gist.github.com/joescii/4431cb2185eddb699dfb79b9c910e333 到 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，我对它的内部结构有了更多的了解。

如果有人遇到类似问题，我会发帖。