at:tutorial:objects
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at:tutorial:objects [2007/06/29 14:24] – jorge | at:tutorial:objects [2007/07/02 13:12] – jorge | ||
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Every object understands the message '' | Every object understands the message '' | ||
+ | |||
+ | AmbientTalk also provides a '' | ||
+ | |||
+ | < | ||
+ | > def clonedPoint := clone: point | ||
+ | </ | ||
===== Delegation and cloning ===== | ===== Delegation and cloning ===== | ||
- | AmbientTalk features object inheritance or delegation. By means of delegation, an object can reuse and extend the defintion of another establishing a parent-child relationship. We identify two kinds of delegation relationships: | + | AmbientTalk features object inheritance or delegation. By means of delegation, an object can reuse and extend the defintion of another establishing a parent-child relationship. We identify two kinds of delegation relationships: |
+ | |||
+ | |||
+ | {{: | ||
The following code shows how to extend objects with a **IS-A** relationship. It uses the '' | The following code shows how to extend objects with a **IS-A** relationship. It uses the '' | ||
Line 75: | Line 85: | ||
===== Delegation and dynamic inheritance ===== | ===== Delegation and dynamic inheritance ===== | ||
- | The parent of an object is bound to a field named '' | + | The parent of an object is bound to a field named '' |
- | ===== First-class | + | < |
+ | > def OpenConnection := object: {...}; | ||
+ | def ClosedConnection := object: {...}; | ||
+ | def Connection := object: { | ||
+ | def open() { | ||
+ | super := OpenConnection.new(); | ||
+ | }; | ||
+ | def close() { | ||
+ | super := ClosedConnection.new(); | ||
+ | }; | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | ===== First-class | ||
+ | AmbientTalk provides an explicit delegation operator '' | ||
+ | |||
+ | < | ||
+ | > def Point3D := extend: Point with: { | ||
+ | def z := 0; | ||
+ | def init(anX, aY, aZ) { | ||
+ | super^init(anX, | ||
+ | z := aZ; | ||
+ | } | ||
+ | } | ||
+ | </ | ||
===== Encapsulation ===== | ===== Encapsulation ===== | ||
+ | In AmbientTalk, | ||
+ | < | ||
+ | > def makeObject(hidden) { | ||
+ | object: { | ||
+ | def foo() { /* use hidden */ } | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | Due to the encapsulation of this object the following instruction fails: | ||
+ | |||
+ | < | ||
+ | > makeObject(5).hidden; | ||
+ | >> | ||
+ | < | ||
+ | </ |
at/tutorial/objects.txt · Last modified: 2013/05/17 20:23 by tvcutsem