Sbt：从根项目调用子项目的源代码

Question

所以我的项目结构如下：我的根项目包含设置、任务和配置。此外，它还有一个子项目文件夹，其中包含所有子项目。我在根项目上创建了一个任务，该任务依赖于子项目X中的一些代码。是否可以在该任务定义中调用子项目X的方法？

我的代码如下：

lazy val rootSettings: Seq[Setting[_]] = Seq (someRootTask :=  { //I need to call an object from a subproject here..}) 

我尝试使用反射api，但没有成功：

import scala.reflect.runtime.{universe => u }
lazy val docSettings: Seq[Setting[_]] = Seq(
rootTask := {
val subproject = baseDirectory.in(playApp).value.getAbsolutePath
val mirror = u.runtimeMirror(getClass.getClassLoader)
val clazz = mirror.staticModule(subproject+"/" +"controllers.pckg.obj" ) 
val cm = mirror.reflectModule(clazz)
val instanceMirror = mirror.reflect(cm.instance)
val methodName ="sayHi" 
val methodSymbol = u.typeOf[instanceMirror.type].declaration(u.newTermName(methodName)).asMethod
val method = instanceMirror.reflectMethod(methodSymbol)
method.apply()
}
)
// still can't point to the object i want to call. 

上面的代码引发了一个错误。它找不到对象，我知道它的路径，但我不能从根项目中将其引用为package.class。

Answer 1

从build.sbt 引用scala文件

如果我理解正确，你的项目看起来像

root
project
build.properties
build.sbt
subproject1
src
main
scala
com.example.package1
App.scala
subproject2
src
main
scala
com.example.package2
build.sbt

在project/build.sbt中，我可以编写

Compile / unmanagedSourceDirectories += baseDirectory.value / ".." / "subproject1" / "src" / "main" / "scala"

假设subproject1/src/main/scala/com/example/package1/App.scala是

package com.example.package1
object App {
def foo(): Unit = println("foo")
}

然后在根build.sbt中，我可以调用foo

name := "sbtdemo"
version := "0.1"
ThisBuild / scalaVersion := "2.13.4"
lazy val sampleUnitTask = taskKey[Unit]("A sample unit task.")
lazy val rootSettings: Seq[Setting[_]] = Seq(
sampleUnitTask := {
com.example.package1.App.foo()
}
)
lazy val root = project
.in(file("."))
.dependsOn(subproject1, subproject2)
.settings(rootSettings)
lazy val subproject1 = project
.in(file("subproject1"))
lazy val subproject2 = project
.in(file("subproject2"))

如果在sbt shell中运行root/sampleUnitTask，它将打印foo。

---

我用sbt new playframework/play-scala-seed.g8创建了Play项目。一切似乎都正常。我如上所述添加了project/build.sbt和subproject1/src/main/scala/com/example/package1/App.scala。然后使用以下根build.sbt

name := """playframeworkdemo"""
organization := "com.example"
version := "1.0-SNAPSHOT"
lazy val sampleUnitTask = taskKey[Unit]("A sample unit task.")
lazy val rootSettings: Seq[Setting[_]] = Seq(
sampleUnitTask := {
com.example.package1.App.foo()
}
)
lazy val root = (project in file(".")).enablePlugins(PlayScala)
.dependsOn(subproject1, subproject2)
.settings(rootSettings)
ThisBuild / scalaVersion := "2.13.3"
libraryDependencies += guice
libraryDependencies += "org.scalatestplus.play" %% "scalatestplus-play" % "5.0.0" % Test
// Adds additional packages into Twirl
//TwirlKeys.templateImports += "com.example.controllers._"
// Adds additional packages into conf/routes
// play.sbt.routes.RoutesKeys.routesImport += "com.example.binders._"
lazy val subproject1 = project
.in(file("subproject1"))
lazy val subproject2 = project
.in(file("subproject2"))

在sbt shell中执行的root/sampleUnitTask打印foo。