components can ask for implicit ComponentInfo

Author: ghik

commons-core/src/main/scala/com/avsystem/commons/di/Component.scala

@@ -25,6 +25,9 @@ case class ComponentInfo(
 object ComponentInfo {
   def apply(namePrefix: String, sourceInfo: SourceInfo): ComponentInfo =
     new ComponentInfo(namePrefix + sourceInfo.enclosingSymbols.head, sourceInfo.filePath, sourceInfo.fileName, sourceInfo.line)
+
+  @compileTimeOnly("implicit ComponentInfo is only available inside code passed to component/singleton macro")
+  implicit def info: ComponentInfo = sys.error("stub")
 }
 
 /**
@@ -212,7 +215,7 @@ trait Components extends ComponentsLowPrio {
     */
   protected[this] def asyncSingleton[T](definition: ExecutionContext => Future[T])(implicit sourceInfo: SourceInfo): Component[T] = macro ComponentMacros.asyncSingleton[T]
 
-  private[this] val singletonsCache = new ConcurrentHashMap[ComponentInfo, AtomicReference[Future[_]]]
+  private[this] lazy val singletonsCache = new ConcurrentHashMap[ComponentInfo, AtomicReference[Future[_]]]
 
   protected[this] def cached[T](component: Component[T], freshInfo: ComponentInfo): Component[T] = {
     val cacheStorage = singletonsCache

commons-core/src/test/scala/com/avsystem/commons/di/ComponentComposition.scala

@@ -0,0 +1,39 @@
+package com.avsystem.commons
+package di
+
+import scala.concurrent.Await
+import scala.concurrent.duration.Duration
+
+abstract class BaseComponent(implicit info: ComponentInfo) {
+  println(s"$info init")
+}
+
+class SubDao(implicit info: ComponentInfo) extends BaseComponent
+class SubService(dao: SubDao)(implicit info: ComponentInfo) extends BaseComponent
+
+class SubSystem extends Components {
+  override protected def componentNamePrefix: String = "sub."
+
+  private val dao: Component[SubDao] =
+    component(new SubDao)
+
+  val service: Component[SubService] =
+    component(new SubService(dao.ref))
+}
+
+class Service(subService: SubService)(implicit info: ComponentInfo) extends BaseComponent
+
+class System(subSystem: SubSystem) extends Components {
+  val service: Component[Service] =
+    component(new Service(subSystem.service.ref))
+}
+
+object ComponentComposition {
+  def main(args: Array[String]): Unit = {
+    val subSystem = new SubSystem
+    val system = new System(subSystem)
+
+    import ExecutionContext.Implicits.global
+    Await.result(system.service.init, Duration.Inf)
+  }
+}

commons-macros/src/main/scala/com/avsystem/commons/macros/di/ComponentMacros.scala

@@ -17,6 +17,7 @@ class ComponentMacros(ctx: blackbox.Context) extends AbstractMacroCommons(ctx) {
   lazy val ComponentTpe: Type = getType(tq"$ComponentCls[_]")
   lazy val ComponentRefSym: Symbol = ComponentTpe.member(TermName("ref"))
   lazy val InjectSym: Symbol = getType(tq"$DiPkg.Components").member(TermName("inject"))
+  lazy val ComponentInfoSym: Symbol = getType(tq"$DiPkg.ComponentInfo.type").member(TermName("info"))
 
   object ComponentRef {
     def unapply(tree: Tree): Option[Tree] = tree match {
@@ -30,6 +31,7 @@ class ComponentMacros(ctx: blackbox.Context) extends AbstractMacroCommons(ctx) {
 
   private def mkComponent(tpe: Type, sourceInfo: Tree, definition: Tree, singleton: Boolean, async: Boolean): Tree = {
     val depArrayName = c.freshName(TermName("deps"))
+    val infoName = c.freshName(TermName("info"))
     val depsBuf = new ListBuffer[Tree]
 
     def validateDependency(tree: Tree): Tree = {
@@ -54,6 +56,8 @@ class ComponentMacros(ctx: blackbox.Context) extends AbstractMacroCommons(ctx) {
           depsBuf += validateDependency(component)
           val depTpe = component.tpe.baseType(ComponentTpe.typeSymbol).typeArgs.head
           q"$depArrayName(${depsBuf.size - 1}).asInstanceOf[$depTpe]"
+        case t if t.symbol == ComponentInfoSym =>
+          q"$infoName"
         case _ =>
           super.transform(tree)
       }
@@ -75,13 +79,15 @@ class ComponentMacros(ctx: blackbox.Context) extends AbstractMacroCommons(ctx) {
 
     val result =
       q"""
+        val $infoName = ${c.prefix}.componentInfo($sourceInfo)
         new $DiPkg.Component[$tpe](
-          ${c.prefix}.componentInfo($sourceInfo),
+          $infoName,
           $ScalaPkg.IndexedSeq(..${depsBuf.result()}),
           ($depArrayName: $ScalaPkg.IndexedSeq[$ScalaPkg.Any]) => $asyncDefinition
         )
        """
 
+    //TODO: can I avoid recreating ComponentInfo?
     if (singleton)
       q"${c.prefix}.cached($result, ${c.prefix}.componentInfo($sourceInfo))"
     else