如何为SBT中的所有子项目设置默认依赖关系？

Question

尝试了解如何设置SBT subprojects。为我的所有子项目设置默认依赖关系的正确方法是什么？

我试过了，但是我的子项目没有提取任何依赖项(它们下载得很好)。

import sbt._

class MyProjects(info: ProjectInfo) extends DefaultProject(info)
{
  val projA = project("projA", "ProjectA")
  val projB = project("projB", "ProjectB")

  val akkaRepo = "Akka maven2 repo" at "http://www.scalablesolutions.se/akka/repository/"
  val multiverseRepo = "Multiverse maven2 repo" at "http://multiverse.googlecode.com/svn/maven-repository/releases/"
  val guiceyFruitRepo = "GuiceyFruit Maven2 repo" at "http://guiceyfruit.googlecode.com/svn/repo/releases/"
  val jBossRepo = "JBoss maven2 repo" at "https://repository.jboss.org/nexus/content/groups/public/"

  val junit = "junit" % "junit" % "4.5" % "test"
  val scalatest = "org.scalatest" % "scalatest" % "1.2" % "test"
  val akka = "se.scalablesolutions.akka" % "akka-core_2.8.0" % "0.10"
}

然后，基于this，我尝试了以下方法。它起作用了，但这不是我想要做的。难道没有更简单的was来设置所有子项目的默认依赖关系吗？

import sbt._  

class MyProjects(info: ProjectInfo) extends DefaultProject(info)
{
  val projA = project("projA", "ProjectA", new Proj(_))
  val projB = project("projB", "ProjectB", new Proj(_))

  val akkaRepo = "Akka maven2 repo" at "http://www.scalablesolutions.se/akka/repository/"
  val multiversRepo = "Multiverse maven2 repo" at "http://multiverse.googlecode.com/svn/maven-repository/releases/"
  val guiceyFruitRepo = "GuiceyFruit Maven2 repo" at "http://guiceyfruit.googlecode.com/svn/repo/releases/"
  val jBossRepo = "JBoss maven2 repo" at "https://repository.jboss.org/nexus/content/groups/public/"

  class Proj(info:ProjectInfo) extends DefaultProject(info){
    val junit = "junit" % "junit" % "4.5" % "test"
    val scalatest = "org.scalatest" % "scalatest" % "1.2" % "test"
    val akka = "se.scalablesolutions.akka" % "akka-core_2.8.0" % "0.10"
  }
}

编辑:应该指出有一个使用Akka的better way，但只是说明了我的观点。

Answer 1

使用继承和混合：

import sbt._

class ModularProject(info: ProjectInfo) extends DefaultProject(info){

    lazy val childProject = project("projA", "ProjectA", 
        new DefaultProject(_)   
            with Repositories 
            with GlobalDependencies
            with AkkaDependencies)

    trait Repositories{
        lazy val akkaRepo = "Akka maven2 repo" at 
        "http://www.scalablesolutions.se/akka/repository/"
        lazy val multiversRepo = "Multiverse maven2 repo" at 
        "http://multiverse.googlecode.com/svn/maven-repository/releases/"
        lazy val guiceyFruitRepo = "GuiceyFruit Maven2 repo" at 
        "http://guiceyfruit.googlecode.com/svn/repo/releases/"
        lazy val jBossRepo = "JBoss maven2 repo" at 
        "https://repository.jboss.org/nexus/content/groups/public/"
    }

    trait GlobalDependencies{
        lazy val junit = "junit" % "junit" % "4.5" % "test"
        lazy val scalatest = "org.scalatest" % "scalatest" % "1.2" % "test"
    }

    trait AkkaDependencies{
        lazy val akka = "se.scalablesolutions.akka" % "akka-core_2.8.0" % "0.10"
    }       

}

Answer 2

通常的解决方案是将每个子项目的依赖项放在一个类中，就像您对Proj-class所做的那样。通常每个子项目需要一个类，因为它们通常具有唯一的依赖关系。

如果你很懒，你可以用内联依赖声明类：

object Dependencies {
    ....
    lazy val jodaTime = "joda-time" % "joda-time" % ...
    lazy val scalaTime = "org.scala-tools" % "time" % ...
    lazy val redis = "com.redis" % "redisclient" % ...
}

val xBase = project("x-base", "x-base", new DefaultProject(_) {
    val jodaTime = Dependencies.jodaTime
    val scalaTime = Dependencies.scalaTime
  })

val xY = project("x-y", "x-y", new DefaultProject(_) { val redis = Dependencies.redis }, xBase)

在上面的示例中(对于产品x)，xY模块依赖于xBase模块。

Dependencies对象使得重用模块中的依赖项变得很容易。

Answer 3

自那以后发生了很大的变化，在SBT0.13.x中，现在可以在aggregate的其他子项目(然后将设置分辨率委托给该项目)的根项目中使用project/RootBuild.scala设置所有子项目的默认依赖项，如下所示：

import sbt._
import Keys._

object RootBuild extends Build {
  override lazy val settings = super.settings ++
    Seq(resolvers += "Akka maven2 repo" at "http://www.scalablesolutions.se/akka/repository/")
}

设置了resolvers之后，子项目也会设置它。

[root]> resolvers
[info] a/*:resolvers
[info]  List(Akka maven2 repo: http://www.scalablesolutions.se/akka/repository/)
[info] b/*:resolvers
[info]  List(Akka maven2 repo: http://www.scalablesolutions.se/akka/repository/)
[info] root/*:resolvers
[info]  List(Akka maven2 repo: http://www.scalablesolutions.se/akka/repository/)

根工程的build.sbt如下：

lazy val root = project in file(".") aggregate (a, b)

lazy val a = project dependsOn b

lazy val b = project

有关.scala Build Definition，请参考sbt的官方文档。

然而，还有另一个(更好的？)使用ThisBuild作用域定义通用配置的方法。

lazy val root = project in file(".") aggregate (a, b)

lazy val a = project dependsOn b

lazy val b = project

resolvers in ThisBuild += "JBoss maven2 repo" at "https://repository.jboss.org/nexus/content/groups/public/"

使用上面的RootBuild.scala构建定义和build.sbt，我在其中使用in ThisBuild来确定整个构建的设置范围，构建配置最终在多项目设置中以两个resolvers作为默认值。

[root]> resolvers
[info] a/*:resolvers
[info]  List(Akka maven2 repo: http://www.scalablesolutions.se/akka/repository/, JBoss maven2 repo: https://repository.jboss.org/nexus/content/groups/public/)
[info] b/*:resolvers
[info]  List(Akka maven2 repo: http://www.scalablesolutions.se/akka/repository/, JBoss maven2 repo: https://repository.jboss.org/nexus/content/groups/public/)
[info] root/*:resolvers
[info]  List(Akka maven2 repo: http://www.scalablesolutions.se/akka/repository/, JBoss maven2 repo: https://repository.jboss.org/nexus/content/groups/public/)