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at:tutorial:objects [2007/07/09 21:38] – rewrote tvcutsemat:tutorial:objects [2007/07/10 12:42] tvcutsem
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 </code> </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 (''aX'' and ''aY'' in the example code). Hence, the ''init'' method plays the role of "constructor" for AmbientTalk objects. Hence, in the code above, ''anotherPoint'' shares its methods with its ''Point'' prototype, but it has its own set of fields:+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 code). Hence, the ''init'' method plays the role of "constructor" for AmbientTalk objects. In the above code, ''anotherPoint'' shares its methods with its ''Point'' prototype, but it has its own set of fields:
  
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 In this example, ''Point3D'' delegates any message it does not understand to ''Point''. The ''extend:with:'' construct creates a new object whose ''super'' slot is automatically set to the given parent object. The delegation relationship is **IS-A** because a ''Point3D'' is a kind of 2D ''Point'', and a ''z'' coordinate (conceptually) cannot exist without a corresponding ''x'' and ''y'' coordinate. In this example, ''Point3D'' delegates any message it does not understand to ''Point''. The ''extend:with:'' construct creates a new object whose ''super'' slot is automatically set to the given parent object. The delegation relationship is **IS-A** because a ''Point3D'' is a kind of 2D ''Point'', and a ''z'' coordinate (conceptually) cannot exist without a corresponding ''x'' and ''y'' coordinate.
  
-A **SHARES-A** relationship between two objects signifies that an object only delegates to another object purely for reasons of code sharing. The delegation link has no other semantics, and conceptually both parent and child can exist without one another.+A **SHARES-A** relationship between two objects signifies that an object only delegates to another object purely for reasons of code or state sharing. The delegation link has no other semantics, and conceptually both parent and child can exist without one another.
  
 The following code shows how to extend objects with a **SHARES-A** delegation relationship. It uses the ''share: with:'' language construct. The following code shows how to extend objects with a **SHARES-A** delegation relationship. It uses the ''share: with:'' language construct.
at/tutorial/objects.txt · Last modified: 2013/05/17 20:23 by tvcutsem