Is it possible to extend build.sbt syntax using implicit classes? - scala

Question

I have a big root sbt project that contains several sub-projects. Among those project definitions there is a lot of code duplication that I am trying to remove.
For example every assembly project contains the following code:
project
.enablePlugins(sbtassembly.AssemblyPlugin)
.settings(
mainClass in Compile := Some(mainClassName),
assemblyJarName in assembly := jarName,
assemblyMergeStrategy in assembly := {
case PathList("META-INF", xs#_*) => MergeStrategy.discard
case PathList("sandbox.sc") => MergeStrategy.discard
case PathList("org", "joda", "time", xs#_*) => MergeStrategy.first
case PathList("reference.conf") => MergeStrategy.concat
case x => MergeStrategy.deduplicate
}
)
Instead i would like to write something like that:
project
.assembly(className, jarName)
Is it possible to achieve such syntax? I know it is possible to achieve this syntax in a typical scala file using an implicit class. Is these a way to do it in sbt ?

Answer 1

Yes, it's possible. create object(SbtProjectImplicits.scala) under the project directory(depend on your project structure), like:
your-project/
project/SbtProjectImplicits.scala
src/
...
and the SbtProjectImplicits.scala object content maybe like:
object SbtProjectImplicits {
implicit class ProjectSettings(p: sbt.Project) {
def assembly(className: Class, jarName): sbt.Project = {
p.settings(
mainClass in Compile := Some(mainClassName),
assemblyJarName in assembly := jarName,
...
)
p
}
}
}
so you can in build.sbt do it like:
import SbtProjectImplicits._
project
.assembly(className, jarName)