Delegates: Difference between revisions

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@@ Line 754: / Line 754: @@
 =={{header|Elena}}==
-ELENA 3.2 :
+ELENA 3.4 :
 Using multi methods:
 <lang elena>import extensions.
 import system'routines.
-class IOperable
+interface IOperable
 {
-    operate
+    abstract operate []
-    [
-        NotSupportedException new; raise.
-    ]
 }
 class Operable :: IOperable
 {
+    constructor new []
     operate
         = "delegate implementation".
@@ Line 777: / Line 776: @@
 {
     object theDelegate.
+    set Delegate:object
-    constructor new
     [
-        theDelegate := nil.
+        if(nil == object)
+        [
+            theDelegate := nilValue.
+        ];
+        [
+            theDelegate := object.
+        ]
     ]
+    private operate(object operable)
-    set Delegate:obj
-    [
-        if ($nil == obj)
-            [ theDelegate := $nil. ];
-            [ theDelegate := obj. ].
-    ]
-    operate(Object operable)
         = "default implementation".
-    operate(IOperable operable)
+    private operate(IOperable operable)
         = operable operate.
     operate
         <= operate(theDelegate).
 }
-program =
+public program
 [
     var delegator := Delegator new.
@@ Line 810: / Line 808: @@
        console printLine(delegator operate).
     ].
-].</lang>
+]</lang>
 Generic solution:
-<lang elena>
+<lang elena>import extensions.
-import extensions.
 import system'routines.
 class Operable
 {
-    operable = $self.
+    operable = self.
     operate
@@ Line 826: / Line 823: @@
 class Delegator
 {
-    object theDelegate.
+    object prop Delegate :: theDelegate.
     constructor new
     [
         theDelegate := nil.
-    ]
-    set Delegate:obj
-    [
-        if ($nil == obj)
-            [ theDelegate := $nil. ];
-            [ theDelegate := obj. ].
     ]
@@ Line 843: / Line 833: @@
     [
         // if the object does not support "get&operable" message - returns nil
-        var anOperable := theDelegate operable \ back:$nil.
+        var anOperable := theDelegate operable \ back:nil.
-        if ($nil == anOperable)
+        if (nil == anOperable)
         [
             ^ "default implementation".
@@ Line 855: / Line 845: @@
 }
-program =
+public program
 [
     var delegator := Delegator new.
@@ Line 865: / Line 855: @@
        console printLine(delegator operate).
     ].
-].</lang>
+]</lang>
 {{out}}
 <pre>