Data update

Task/Delegates/Pluto/delegates.pluto

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+class thingable
+    function thing() end
+end
+
+-- Delegate that doesn't implement thingable.
+class delegate
+    function __construct() end
+end
+
+-- Delegate that implements thingable.
+class delegate2 extends thingable
+    function __construct() end
+
+    function thing() return "delegate implementation" end
+end
+
+class delegator
+    function __construct()
+        self.delegate = nil
+    end
+
+    function operation()
+        if !self.delegate or !(self.delegate instanceof thingable) then
+            return "default  implementation"
+        end
+        return self.delegate:thing()
+    end
+end
+
+-- Without a delegate.
+local d = new delegator()
+print(d:operation())
+
+-- With a delegate that doesn't implement thingable.
+d.delegate = new delegate()
+print(d:operation())
+
+-- With a delegate that does implement thingable.
+d.delegate = new delegate2()
+print(d:operation())