Hello to all of you! I have the following problem: suppose I have defined
a class Geometric
(defclass Geometric ()
((color :accessor color :initform 'black))
(:documentation "The basic class for all graphical objects.Slot:
Color"))
I want to define a before and after methods that are suppose to
show the color right before/after changing it. I tried the following code:
(defgeneric set_color ((new_color list) (obj Geometric))
(:method ((new_color list)(obj Geometric)) (setf (color obj) new_color)
))
(defmethod set_color :before ((new_value list) (obj Geometric))
(print 'before (color obj))
)
but the interpreter comes up with an error:
USER(37): (set_color 'black g) Error: No methods applicable for generic
function
#<STANDARD-GENERIC-FUNCTION SET_COLOR> with args
(BLACK #<GEOMETRIC @ #x2039cd0a>) of classes (SYMBOL GEOMETRIC)
[condition type: PROGRAM-ERROR]
Any idea why or where is the mistake?
Thank you in advance...
"Ralitsa" <···@abv.bg> wrote in message
·································@posting.google.com...
> Hello to all of you! I have the following problem: suppose I have defined
> a class Geometric
Hi Ralitsa,
I understand your problem may be urgent, but it isn't better to ask the same
question 3 times!
--
Coby Beck
(remove #\Space "coby 101 @ bigpond . com")