at:tutorial:objects
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at:tutorial:objects [2007/06/27 11:59] – jorge | at:tutorial:objects [2007/06/29 14:31] – jorge | ||
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< | < | ||
- | > def Point := object: { | + | > def point := object: { |
def x := 0; | def x := 0; | ||
def y := 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 }; | def sumOfSquares() { x*x + y*y }; | ||
} | } | ||
- | >>< | ||
</ | </ | ||
- | The state of the '' | + | As all definitions in AmbientTalk, |
- | This object can be instantiated to create new points as follows: | + | |
- | <code> | + | <note important> |
- | > def initialPoint := Point.new(0,0) | + | AmbientTalk not only supports traditional canonical syntax (e.g. '' |
- | >>< | + | </note> |
- | </code> | + | |
- | Every object understands | + | In the example above, the state of the '' |
===== Sending messages ===== | ===== Sending messages ===== | ||
- | In AmbientTalk, | + | In AmbientTalk, |
- | ===== Cloning and instantiation ===== | + | < |
+ | > point.x | ||
+ | >>2 | ||
+ | > point.sumOfSquares() | ||
+ | >> | ||
+ | </ | ||
+ | This code shows two messages sent to the '' | ||
+ | ===== Cloning and instantiation ===== | ||
+ | As said before in this section, AmbientTalk objects are created [[objects# | ||
- | ===== Delegation | + | < |
+ | > def anotherPoint := point.new(2, | ||
+ | </ | ||
+ | |||
+ | Every object understands the message '' | ||
===== 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: | ||
+ | |||
+ | The following code shows how to extend objects with a **IS-A** relationship. It uses the '' | ||
+ | |||
+ | < | ||
+ | > def point3D := extend: point with: { | ||
+ | def z := 0; | ||
+ | def sumofsquares() { | ||
+ | super.sumofsquares() + z*z | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | The following code shows how to extend objects with a **SHARE-A** relationship. It uses the '' | ||
+ | |||
+ | < | ||
+ | > def point3D := share: point with: { | ||
+ | def z := 0; | ||
+ | def sumofsquares() { | ||
+ | super.sumofsquares() + z*z | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | ===== Delegation and dynamic inheritance ===== | ||
+ | The parent of an object is bound to a field named '' | ||
+ | |||
+ | < | ||
+ | > def OpenConnection := object: {...}; | ||
+ | def ClosedConnection := object: {...}; | ||
+ | def Connection := object: { | ||
+ | def open() { | ||
+ | super := OpenConnection.new(); | ||
+ | }; | ||
+ | def close() { | ||
+ | super := ClosedConnection.new(); | ||
+ | }; | ||
+ | } | ||
+ | </ | ||
===== First-class Delegation ===== | ===== First-class Delegation ===== |
at/tutorial/objects.txt · Last modified: 2013/05/17 20:23 by tvcutsem