How to write a plugin which depends on a task from another plugin? - plugins

Question

There is a great sbt plugin sbt-dependency-graph, which provides a dependencyTree task to show the dependencies.
I want to write a sbt plugin which depends on it, but always fails.
build.sbt
sbtPlugin := true
name := "my-sbt-plugin-depends-on-another"
version := "0.1.2.1"
organization := "test20140913"
addSbtPlugin("net.virtual-void" % "sbt-dependency-graph" % "0.7.5")
src/main/scala/MySbtPlugin.scala
import sbt._
object MySbtPlugin extends AutoPlugin {
object autoImport {
lazy val hello = taskKey[Unit]("hello task from my plugin")
lazy val hello2 = taskKey[Unit]("hello task from my plugin2")
}
import autoImport._
override def trigger = allRequirements
override def requires = plugins.JvmPlugin
val helloSetting = hello := println("Hello from my plugin")
val helloSetting2 = hello2 := {
println("hello2, task result from another plugins:")
println(net.virtualvoid.sbt.graph.Plugin.dependencyTree.value)
println("=========================================")
}
override def projectSettings = Seq(
helloSetting, helloSetting2
)
}
Then I published it to local, and use it in another project:
build.sbt
name := "sbt--plugin-test"
version := "1.0"
scalaVersion := "2.11.6"
net.virtualvoid.sbt.graph.Plugin.graphSettings
project/plugins.scala
logLevel := Level.Info
addSbtPlugin("net.virtual-void" % "sbt-dependency-graph" % "0.7.5")
addSbtPlugin("test20140913" % "my-sbt-plugin-depends-on-another" % "0.1.2.1")
When I run sbt on the later project, it reports:
Reference to undefined setting:
*:dependencyTree from *:hello2 (/Users/twer/workspace/my-sbt-plugin-depends-on-another/src/main/scala/test20140913/MySbtPlugin.scala:38)
Did you mean provided:dependencyTree ?
at sbt.Init$class.Uninitialized(Settings.scala:262)
at sbt.Def$.Uninitialized(Def.scala:10)
at sbt.Init$class.delegate(Settings.scala:188)
at sbt.Def$.delegate(Def.scala:10)
Where is wrong?
PS: The plugin code is here: https://github.com/freewind/my-sbt-plugin-depends-on-another

Answer 1

dependencyTree is only defined for specific configurations (well all of them), but it automatically delegates to Compile in the shell.
Try defining hello2 like so:
val helloSetting2 = hello2 := {
println("hello2, task result from another plugins:")
import net.virtualvoid.sbt.graph.Plugin.dependencyTree
println((dependencyTree in Compile).value)
println("=========================================")
}