Fichier objets.ex / 2 mars 2000

Welcome to DrScheme, version 101.
Language: Graphical Full Scheme (MrEd).

> (define toto% (class object% () (public (x 3)) (sequence (super-init))))

> (define toto1 (make-object toto%))

> toto%
#<class:toto%>

> toto1
#<object:toto%>

> (ivar toto1 x)
3

Heritage:
-----------

> (define titi% (class toto% () (public (y sqrt)) (sequence (super-init))))

> (define titi1 (make-object titi%))

> (ivar titi1 x)
3

> (ivar titi1 y)
#<primitive:sqrt>

> (send titi1 y 9)
3

> (send titi1 y 25)
5

> ((ivar titi1 y) 25)
5

> (ivar titi1 x)
3

> (send titi1 y 2 3)
sqrt: expects 1 argument, given 2: 2 3


Modification de variable:
-----------------------------
on ne peut pas le faire sur les variables heritees

> (define tutu% (class object% () (public (x 0) (z (lambda (u) (set! x u)))) (sequence (super-init))))

> (define tutu1 (make-object tutu%))

> (send tutu1 z 4)

> (ivar tutu1 x)
4

> (send tutu1 z 734693896359)

> (ivar tutu1 x)
734693896359

> x
reference to undefined identifier: x

> (ivar toto1 x)
3