at:tutorial:objects
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Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
at:tutorial:objects [2007/07/02 11:20] – jorge | at:tutorial:objects [2007/07/02 13:35] – 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 '' | ||
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> def point3D := extend: point with: { | > def point3D := extend: point with: { | ||
def z := 0; | def z := 0; | ||
- | def sumofsquares() { | + | def sumOfSquares() { |
- | super.sumofsquares() + z*z | + | super^sumOfSquares() + z*z |
} | } | ||
} | } | ||
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> def point3D := share: point with: { | > def point3D := share: point with: { | ||
def z := 0; | def z := 0; | ||
- | def sumofsquares() { | + | def sumOfSquares() { |
- | super.sumofsquares() + z*z | + | super^sumOfSquares() + z*z |
} | } | ||
} | } | ||
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< | < | ||
- | > def OpenConnection | + | > def openConnection |
- | def ClosedConnection | + | > def closedConnection |
- | def Connection | + | > def connection |
- | def open() { | + | def open() { |
- | super := OpenConnection.new(); | + | super := openConnection.new(); |
}; | }; | ||
def close() { | def close() { | ||
- | super := ClosedConnection.new(); | + | super := closedConnection.new(); |
}; | }; | ||
} | } | ||
</ | </ | ||
- | ===== First-class | + | ===== First-class |
+ | AmbientTalk provides an explicit delegation operator '' | ||
+ | |||
+ | < | ||
+ | > def point3D := extend: point with: { | ||
+ | def z := 0; | ||
+ | def init(aX, aY, aZ) { | ||
+ | super^init(aX, | ||
+ | z := aZ; | ||
+ | }; | ||
+ | } | ||
+ | </ | ||
+ | A message sent to an object using this symbol (e.g. to the parent object in the example above) will first look for the method that matches the selector indicated in the message in this object (and its parents) and then execute the method body in the lexical scope of the message sender. | ||
===== Encapsulation ===== | ===== Encapsulation ===== |
at/tutorial/objects.txt · Last modified: 2013/05/17 20:23 by tvcutsem