Data commit

Task/Delegates/F-Sharp/delegates.fs

@@ -0,0 +1,26 @@
+type Delegator() =
+  let defaultOperation() = "default implementation"
+  let mutable del = null
+
+  // write-only property "Delegate"
+  member x.Delegate with set(d:obj) = del <- d
+
+  member x.operation() =
+    if del = null then
+      defaultOperation()
+    else
+      match del.GetType().GetMethod("thing", [||]) with
+      | null -> defaultOperation()
+      | thing -> thing.Invoke(del, [||]) :?> string
+
+type Delegate() =
+  member x.thing() = "delegate implementation"
+
+let d = new Delegator()
+assert (d.operation() = "default implementation")
+
+d.Delegate <- "A delegate may be any object"
+assert (d.operation() = "default implementation")
+
+d.Delegate <- new Delegate()
+assert (d.operation() = "delegate implementation")