Demo of specifying an explicit Execution Context to a method to override a default implicit one.

EcTest.scala

object EcTest extends App {

  import scala.concurrent.Future
  import scala.concurrent.ExecutionContext
  import java.util.concurrent.Executors


  val default = scala.concurrent.ExecutionContext.Implicits.global

  def test(comp: String)(implicit exc: ExecutionContext = default): Future[String] = Future { 
    println("Using executor: " + Thread.currentThread().getName)
    comp 
  }

  test("Use default executor")

  val myExecutor = ExecutionContext.fromExecutor(Executors.newSingleThreadExecutor)
  test("Use custom executor")(myExecutor)

}