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 子项目。为我的所有子项目设置默认依赖项的正确方法是什么？

我尝试了这个，但是我的子项目没有获取任何依赖项（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，基于这个我尝试了以下操作。它有效，但这不是我期望要做的。是否有更简单的方法为所有子项目设置默认依赖项？

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：应该指出有一个更好的方法来使用Akka，但只是说明我的观点。

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

正常的解决方案是将依赖项放入每个子项目的一个类中，就像您对 Proj 类所做的那样。通常每个子项目都需要一个类，因为它们通常具有独特的依赖关系。

如果您很懒，您可以声明具有内联依赖项的类：

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 对象可以轻松地重用模块中的依赖关系。

Answer 3

此后发生了很多变化，在 sbt 0.13.x 中，现在可以在根项目中使用 project/RootBuild.scala 来“为所有子项目设置默认依赖项” 聚合其他子项目（然后将设置解析委托给它们），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后，子项目也将进行设置。

[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/)

根项目的build.sbt如下：

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

lazy val a = project dependsOn b

lazy val b = project

查阅sbt官方文档了解.scala 构建定义。

然而，还有另一种（更好？）方法来定义通用配置 ThisBuild 范围。

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/"

通过上面的 RootBuild.scala 构建定义和 build.sbt，我在 ThisBuild 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默认有两个解析器。

[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/)