! object message

sends the message "message" to the object "object" 



A message is a word (property name or method name) 
                      a list  of the form [ <metod name> < parameters> ]

With a property name  ! outputs the property value  or an empty list if no value
is found.

With a method name, the procedure corresponding to the method is runed  and a 
result is returned  when the procedure returns a result. If the procedure is not
found an empty list is returned. This produces an error " I don't know what to do
 with [] " if the method is a command (don't return a result).

Example:

! "object [create "human]
! "human[make "food [milk meat vegetables]]
show ! "human "food
! "human "destroy

-----------------------------------------------------------------------------------
!O message   

message to current object.

!o  sends the message "message" to the current object

It is equivalent to ! :object  

At run time the variable :object contain the name of the object receiving the 
message.

The tittle of !  is   to ! :object  :&p    and while ! is running  :object is 
containing the name of the object, if not masked  by an other call of ! . 



!o should be used in a method. The current object is the object that has received
a message with that method. 

A message is a word (property name or method name) 
                      a list  of the form [ ]

With a property name  ! outputs the property value  or an empty list if no value 
is found.

With a method name, the procedure corresponding to the method is runed  and a 
result is returned  when the procedure returns a result. If the procedure is not
found an empty list is returned. This produces an error I don't know what to do
with [] if the method is a command (a command  doesn't return a result).

Example:

! "object [create "poly]
! "poly [make "nside 5 ] ; 5 will be the default number of sides for all 
                         ; descendants of poly
! "poly [make "size 100] ; 100 will be the default size  for all descendants of 
                         ; poly
! "poly [method "draw]   ; will open the editor with to poly.draw as title of the 
                         ;procedure.

; in the editor  :

to poly.draw
localmake "ns  !o "nside
localmake "s !o "size
repeat :ns [fd :s rt 360/:ns]
end

; This will define the method draw while exiting the editor.

! "poly "draw ; will draw a polygone with 5 sides and size 100
! "poly [create "square]
! "square [make "nside 4]
cs 
 !  "square "draw  ; will draw a square  since in the line :  
                   ; localmake "ns  !o "nside, 
                   ; ns will get nside  from the object square that receives 
                   ; the message draw.


----------------------------------------------------------------------------------
!S object message

message to super class

sends  "message" to  parent of "object"

Example 

! "object [create "poly]
! "poly [make "nside 5 ] ; 5 will be the default number of sides for all 
                         ; descendants of poly
! "poly [make "size 100] ; 100 will be the default size  for all descendants 
                         ; of poly
! "poly [method "draw]   ; will open the editor with to poly.draw as title of the
                         ; procedure in the editor  :

to poly.draw
localmake "ns  !o "nside
localmake "s !o "size
repeat :ns [fd :s rt 360/:ns]
end

; This will define the method draw while exiting the editor.

! "poly "draw ; will draw a polygone with 5 sides and size 100
! "poly [create "square]
! "square [make "nside 4]
cs 
 !  "square "draw  ; will draw a square  since in the line : 
                   ; localmake "ns  !o "nside, 
                   ; ns will get nside  from the object square that received 
                   ; the message draw.

!s "square "draw   ; Will draw a polygone (5 sides) since the message is send to 
                   ; the parent of square which is polygon.

----------------------------------------------------------------------------------
Predefined methods.

CREATE object

creates a  new object with the current object as parent.

Example:

! "object [create "poly] ; will create the object poly which has object as parent.
                         ;(object is the root of all objects.)  

! "poly [create "square] ; Will create the object square with the object poly as
                         : parent.

----------------------------------------------------------------------------------
METHOD method_name

Define a method for the current object.
It opens the editor with the name of the procedure corresponding to the method.
The name of the procedure is made  as .

Example:
! "object [create "poly]
! "poly [make "nside 5 ]  ; 5 will be the default number of sides for all 
                          ; descendants of poly

! "poly [make "size 100]  ; 100 will be the default size  for all descendants of
                          ; poly

! "poly [method "draw]    ; will open the editor with to poly.draw as title of 
                          ; the procedure in the editor  :

to poly.draw
localmake "ns  !o "nside
localmake "s !o "size
repeat :ns [fd :s rt 360/:ns]
end

; This will define the method draw while exiting the editor.

! "poly "draw ; will draw a polygone with 5 sides and size 100
----------------------------------------------------------------------------------
DESTROY

Destroy the current object and all its descendants but does not erase the 
procedures corresponding to the methods.

Example:

! "poly "destroy

----------------------------------------------------------------------------------
ADD property property_value

If the old value of the property is a word, the method ADD will replace the 
property  by a list with the old value and the new one.
if old value the property  is a list  the method ADD will add the new property 
at the end of the list.

Example:

 ! "object [create "human]
 ! "human [make "food [milk meat vegetables]]
 ! "human [add "food "sugar]
 show ! "human "food
[milk meat vegetables sugar]

 ! "human [make "drink "water]
 ! "human[add "drink "wine]
 show ! "human "drink
[water wine]

-----------------------------------------------------------------------------------
REMOVE property property_value

The method REMOVE  removes a property_value  of a property

Example:

 ! "human [make "drink "water]
 ! "human[add "drink "wine]
 show ! "human "drink
[water wine]
 ! "human [remove "drink "wine]
 show ! "human "drink
[water]

------------------------------------------------------------------------------------
ER property

The method ER erases the property . If the property is a method the corresponding 
procedure is not erased.


 ! "human [make "drink "water]
 show ! "human "drink
[water]
 ! "human [er "drink]
 show ! "human "drink
[]
------------------------------------------------------------------------------------
ANCESTORS

Returns the ancestors of the current object

Example:

! "object [create "human]
 show ! "human "ancestors
[object]

------------------------------------------------------------------------------------
DESCENDANTS

Returns the descendants of the current object  

Example:

! "object [create "human]
 show ! "object "descendants
[human]