Differences

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--- at:tutorial:objects [2007/06/27 14:35] – jorge
+++ at:tutorial:objects [2007/06/29 08:31] – jorge
@@ Line 12: / Line 12: @@
     def x := 0;
     def y := 0;
-    def init(xCoord,yCoord) {
+    def init(aX,aY) {
-      x := xCoord;
+      x := aX;
-      y := yCoord;
+      y := aY;
     };
     def sumOfSquares() { x*x + y*y };
@@ Line 24: / Line 24: @@
 <note important>
-Note that AmbientTalk not only supports traditional canonical syntax (e.g. ''o.m(a,b,c)'') but also keyworded syntax (e.g. ''o.at: key put: value'') for method definitions and message sends, as in SmallTalk.
+AmbientTalk not only supports traditional canonical syntax (e.g. ''o.m(a,b,c)'') but also keyworded syntax (e.g. ''o.at: key put: value'') for method definitions and message sends, as in SmallTalk.
 </note>
@@ Line 34: / Line 34: @@
 </code>
-Every object understands the message ''new'', which creates a clone (a shallow copy) of the receiver object and initializes the clone by invoking its ''init'' method with the arguments that were passed to new (''xCoord'' and ''yCoord'' in the example of the ''Point'' object). Hence, the ''init'' method plays the role of “constructor” for AmbientTalk objects. AmbientTalk’s object instantiation protocol closely corresponds to class instantiation in class-based languages, except that the new object is a clone of an existing object, rather than an empty object allocated from a class. We further explain the semantics of object cloning in subsection [[objects#Delegation_and_cloning|Delegation and cloning]].
+Every object understands the message ''new'', which creates a clone (a shallow copy) of the receiver object and initializes the clone by invoking its ''init'' method with the arguments that were passed to new (''aX'' and ''aY'' in the example of the ''Point'' object). Hence, the ''init'' method plays the role of “constructor” for AmbientTalk objects. AmbientTalk’s object instantiation protocol closely corresponds to class instantiation in class-based languages, except that the new object is a clone of an existing object, rather than an empty object allocated from a class. We further explain the semantics of object cloning in subsection [[objects#Delegation_and_cloning|Delegation and cloning]].
 ===== Sending messages =====
@@ Line 46: / Line 46: @@
 </code>
+This code shows two messages sent to the ''aPoint'' object defined above in this section. The ''x'' message acts as an accessor for the ''x'' field. The ''sumOfSquares'' message selects the ''sumOfSquares'' method and evaluates its body.
 ===== Cloning and instantiation =====
+As said before in this section, AmbientTalk objects are [[objects#Objects,_fields_and_methods|created ex-nihilo]] or by cloning and adapting an existing object.