如何使SBT子项目具有多个Scala版本？

Paul Draper 发表于 Dev

保罗·德雷珀

我有一个使用Scala 2.10的项目，一个使用Scala 2.11的项目。它们取决于可以同时编译的通用项目。

lazy val foo = (project in file("foo")).dependsOn(baz).settings(
  scalaVersion := "2.10.4"
)

lazy val bar = (project in file("bar")).dependsOn(baz).settings(
  scalaVersion := "2.11.4"
)

lazy val baz = (project in file("baz")).settings(
  crossScalaVersions := Seq("2.10.4", "2.11.4"),
  scalaVersion := "2.10.4"
)

接着

$ sbt bar/update
[info] Updating {file:/home/paul/Private/test/}bar...
[info] Resolving baz#baz_2.11;0.1-SNAPSHOT ...
[warn]  module not found: baz#baz_2.11;0.1-SNAPSHOT
[warn] ==== local: tried
[warn]   /home/paul/.ivy2/local/baz/baz_2.11/0.1-SNAPSHOT/ivys/ivy.xml
[warn] ==== public: tried
[warn]   http://repo1.maven.org/maven2/baz/baz_2.11/0.1-SNAPSHOT/baz_2.11-0.1-SNAPSHOT.pom
[info] Resolving jline#jline;2.12 ...
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  ::          UNRESOLVED DEPENDENCIES         ::
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  :: baz#baz_2.11;0.1-SNAPSHOT: not found
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[trace] Stack trace suppressed: run last bar/*:update for the full output.
[error] (bar/*:update) sbt.ResolveException: unresolved dependency: baz#baz_2.11;0.1-SNAPSHOT: not found
[error] Total time: 1 s, completed Jan 13, 2015 11:42:51 AM

如何baz在两个项目中都能使用？

保罗·德雷珀

我为此创建了一个SBT插件。

项目/plugins.sbt

resolvers += Resolver.sonatypeRepo("releases")

addSbtPlugin("com.lucidchart" % "sbt-cross" % "1.0")

build.sbt

lazy val foo = (project in file("foo")).dependsOn(baz_2_10).settings(
  scalaVersion := "2.10.4"
)

lazy val bar = (project in file("bar")).dependsOn(baz_2_11).settings(
  scalaVersion := "2.11.5"
)

lazy val baz = (project in file("baz")).cross

lazy val baz_2_10 = baz("2.10.4")

lazy val baz_2_11 = baz("2.11.5")

它需要花费更多的时间，但是现在所有内容都可以按预期编译：sbt foo/compile可以sbt bar/compile工作。

你不必记住独特的命令，你没有从错误crossPath := false，而不像++，这是并行：sbt compile将编译foo，bar以及baz用正确的斯卡拉版本兼任。