Data commit

Task/Delegates/PicoLisp/delegates.l

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+(class +Delegator)
+# delegate
+
+(dm operation> ()
+   (if (: delegate)
+      (thing> @)
+      "default implementation" ) )
+
+
+(class +Delegate)
+# thing
+
+(dm T (Msg)
+   (=: thing Msg) )
+
+(dm thing> ()
+   (: thing) )
+
+
+(let A (new '(+Delegator))
+   # Without a delegate
+   (println (operation> A))
+
+   # With delegate that does not implement 'thing>'
+   (put A 'delegate (new '(+Delegate)))
+   (println (operation> A))
+
+   # With delegate that implements 'thing>'
+   (put A 'delegate (new '(+Delegate) "delegate implementation"))
+   (println (operation> A)) )