ivyPaths in globalSettings for a plugin - sbt

Question

object BlaBlaPlugin extends AutoPlugin {
object autoImport {
lazy val blabla = settingKey[Unit]("")
}
import autoImport._
override lazy val globalSettings = Seq(
blabla := println(ivyPaths.value.ivyHome.get.getPath)
)
}
I get:
[error] Reference to undefined setting:
[error]
[error] */*:ivyPaths from */*:blabla ((BlaBlaPlugin) BlaBlaPlugin.scala:11)
Isn't ivyPaths defined at a Global scope?
I can access it in .sbt/global.sbt but not in the globalSettings of a plugin.
Cheers

Answer 1

There are several issues with the plugin.
projectSettings
Isn't ivyPaths defined at a Global scope?
No it's not.
> inspect ivyPaths
[info] Setting: sbt.IvyPaths = sbt.IvyPaths#13e5338f
[info] Description:
[info] Configures paths used by Ivy for dependency management.
[info] Provided by:
[info] {file:/Users/xxx/foo/}root/*:ivyPaths
[info] Defined at:
[info] (sbt.Classpaths) Defaults.scala:1128
[info] Dependencies:
[info] *:appConfiguration
[info] *:baseDirectory
[info] Reverse dependencies:
[info] *:cleanCacheIvyDirectory
[info] *:ivyConfiguration
[info] *:blabla
[info] Delegates:
[info] *:ivyPaths
[info] {.}/*:ivyPaths
[info] */*:ivyPaths
This shows that ivyPaths is in the format of {file:/Users/xxx/foo/}root/*:ivyPaths, which is scoped to the current project root. If you're in the mood for Star Wars coding (use the source, Luke) Defaults.scala is usually a good place to start.
So the first thing to change would be to use projectSettings.
override requires
Also note that sbt's builtin settings and tasks are loaded using auto plugins, so if you're depending on them, you need to make sure your plugins are placed after them. To do that you need to override requires method as follows:
override def requires: Plugins = sbt.plugins.IvyPlugin
putting it all together
import sbt._
import Keys._
object BlaBlaPlugin extends AutoPlugin {
override def requires: Plugins = sbt.plugins.IvyPlugin
object autoImport {
lazy val blabla = settingKey[Unit]("")
}
import autoImport._
override lazy val projectSettings = Seq(
blabla := println(ivyPaths.value.ivyHome.get.getPath)
)
}