YAPC::EU 2018 Glasgow Update!

Task/Delegates/Phix/delegates-1.phix

@@ -0,0 +1,44 @@
+enum OTHER, OPERATION
+
+function operation(object o)
+    integer rid = o[OPERATION]
+    if rid!=NULL then
+        return call_func(rid,{})
+    end if
+    return "no implementation"
+end function
+
+function xthing()
+    return "default implementation"
+end function
+
+function newX()
+    return {1,routine_id("xthing"),2}
+end function
+
+function newY()
+    object res = newX()
+    res[OTHER] = "something else"
+    -- remove delegate:
+    res[OPERATION] = NULL
+    return res
+end function
+
+function zthing()
+    return "delegate implementation"
+end function
+
+function newZ()
+    object res = newX()
+    -- replace delegate:
+    res[OPERATION] = routine_id("zthing")
+    return res
+end function
+
+object x = newX(),
+       y = newY(),
+       z = newZ()
+
+?operation(x)
+?operation(y)
+?operation(z)

Task/Delegates/Phix/delegates-2.phix

@@ -0,0 +1,7 @@
+?operation(x)
+try -- (since rid=NULL check commented out)
+    ?operation(y)
+catch e
+    ?"oops, no implementation"
+end try
+?operation(z)

Task/Delegates/Scala/delegates.scala

@@ -0,0 +1,32 @@
+trait Thingable {
+  def thing: String
+}
+
+class Delegator {
+  var delegate: Thingable = _
+
+  def operation: String = if (delegate == null) "default implementation"
+  else delegate.thing
+}
+
+class Delegate extends Thingable {
+  override def thing = "delegate implementation"
+}
+
+// Example usage
+// Memory management ignored for simplification
+object DelegateExample extends App {
+
+  val a = new Delegator
+  assert(a.operation == "default implementation")
+  // With a delegate:
+  val d = new Delegate
+  a.delegate = d
+  assert(a.operation == "delegate implementation")
+  // Same as the above, but with an anonymous class:
+  a.delegate = new Thingable() {
+    override def thing = "anonymous delegate implementation"
+  }
+  assert(a.operation == "anonymous delegate implementation")
+
+}