开发任务以将托管依赖项与 SBT 中的另一个目录同步？

Question

我正在尝试编写一个任务来检索依赖项 jar 并将它们放在项目根目录的单个目录中。到目前为止，这是我所拥有的：

retrieveManaged := true

val libDir = settingKey[File]("the directory to retrieve dependency libraries to")

lazy val getLibs = taskKey[Unit]("retrieves all dependency libraries to the libDir")

libDir := baseDirectory.value / "libs"

getLibs := {
  val a = update.value
  sbt.IO.delete(libDir.value)
  for (src <- (managedDirectory.value ** "*.jar").get) {
    sbt.IO.copyFile(src, libDir.value / src.getName, true)
  }
}

我使用retrieveManaged := true，以便sbt 将依赖项复制到managedDirectory。然后我将这些库复制到我定义的目录中。我的问题是：

1. 我希望我的任务依赖于update 任务，以确保首先将依赖项复制到managedDirectory。如果我理解How can I call another task from my SBT task?，我应该可以通过调用update.value 来做到这一点。但这似乎不起作用。

2. 我真的很想“同步”，而不是复制文件。这意味着只应复制新添加的文件，而应删除不再存在的任何文件。我该怎么做？

更新

感谢 Jacek 的建议，我能够提出以下解决方案，解决 #1。我仍然需要弄清楚如何做#2（同步而不是复制）。

getLibs := {
  sbt.IO.delete(libDir.value)
  val depFiles = update.value.matching((s: String) => Set("compile", "runtime") contains s)
  for (depFile <- depFiles) {
    sbt.IO.copyFile(depFile, libDir.value / depFile.getName, true)
  }
}

Answer 1

我认为答案是真的使用update任务的值并解析其结果。这样就可以解决问题 1 和 2。如果没有，请将症状附加到您的问题中。

所有val a = update.value 都会执行update 任务并将其值分配给a。由于您根本不使用a，因此您丢失了update 为您提供的所有先前信息。要查看它是什么，请在 shell 中执行 show update。

[triggeredby]> help update
Resolves and optionally retrieves dependencies, producing a report.

[triggeredby]> show update
[info] Updating {file:/Users/jacek/sandbox/so/triggeredby/}triggeredby...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Update report:
[info]  Resolve time: 2152 ms, Download time: 114 ms, Download size: 0 bytes
[info]  compile:
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]  runtime:
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]  test:
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]  provided:
[info]  optional:
[info]  compile-internal:
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]  runtime-internal:
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]  test-internal:
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]  plugin:
[info]  sources:
[info]  docs:
[info]  pom:
[info]  scala-tool:
[info]      org.scala-lang:scala-compiler:2.10.3: (Artifact(scala-compiler,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-compiler.jar)
[info]      org.scala-lang:scala-library:2.10.3 (): (Artifact(scala-library,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar)
[info]      org.scala-lang:scala-reflect:2.10.3 (): (Artifact(scala-reflect,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-reflect.jar)
[info]      org.scala-lang:jline:2.10.3: (Artifact(jline,jar,jar,None,List(),None,Map()),/Users/jacek/.sbt/boot/scala-2.10.3/lib/jline.jar)
[info]      org.fusesource.jansi:jansi:1.4: (Artifact(jansi,jar,jar,None,ArraySeq(master),None,Map()),/Users/jacek/.ivy2/cache/org.fusesource.jansi/jansi/jars/jansi-1.4.jar)
[success] Total time: 3 s, completed Mar 14, 2014 12:16:26 AM

我认为这正是您所需要的 - 使用返回值来满足您的需求。