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What is an Object
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From the moment a human is borned, he start recognizing and classifing the
world around. Our brain has the automatic mecanisms to organize our world
into Classes.
An Object is a collection of Data and has some typicall behaviors which
distincts it from other kind of Objects.
Object : Data + Behaviors --> Data + Methods
Data: What the Object HAS.
Behaviors: What the Object DOES.
Example: What is a chair ? Even a child will tell us:
A chair has (DATA) :
* four legs
* a certain colour
* some dimensions
* some weight
* a surface to sit on
* etc...
A chair Behaviors (METHODS) :
* Can be builted
* Can be moved from a place to another
* Supports if someone sits on it
* Can be destroyed
* etc...
In these behaviors we may distinct what the chair DOES and what can
be DONE TO the chair:
The chair does: * Supports if someone sits on it
Someone may destroy the chair --> Something is done to the
chair.
The actions that get DONE TO an Object are EVENTS.
Data: What the Object HAS.
Behaviors: What the Object DOES.
Events: What is DONE to the Object.
Now lets see how we take those concepts into the programming languages:
What is a Window ?
A Window is an Object that HAS:
* Coordinates on the screen.
* A caption
* Some controls on its surface
* A colour
* etc...
A Window DOES:
* Resize
* Iconize
* Change its position
* etc...
Some EVENTS may happen to a Window:
* The mouse Clicks on it
* The user press a key
* The Window gets resized
* etc...
How can we get from an Object a certain action ?
Sending it a Message!
oWindow:Message( params,... )
A message has usually the same name of the Method which gets performed:
oWindow:Refresh() ---> Will execute ---> METHOD Refresh() CLASS TWindow
... more on our OBJECTS product manual ...
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Written by Dave Pearson