<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=UTF-8" http-equiv="Content-Type"> <title></title> </head> <body alink="#ee0000" bgcolor="#ffffff" link="#0000ee" text="#ffffff" vlink="#551a8b"> I'm currently converting the object system called Meroonet used in Christian Queinnec's "Lisp In Small Pieces" to Swindle CLOS. Everything was proceeding more or less smoothly until I ran up against a fundamental difference in the way ancestor field accessors are treated by the two systems. Meroonet takes the position that a class B derived from class A inherits the accessors from class A. Where as Swindle CLOS does not. This means, that in Swindle, for a class B object to access the slots inherited from class A it needs to call them using class A’s accessors. For example in Meroonet it is legal to say: Meroonet (define class Point Object (x y)) (define class ColoredPoint Point (color)) (define thePoint (make-ColoredPoint :x 3 :y 44 :color ‘white)) (set-ColoredPoint-x! thePoint 5) (set-ColoredPoint-y! thePoint 6) (set-ColoredPoint-color! thePoint ‘black) (printf “~n=>~a ~a ~a” (ColoredPoint-x thePoint) (ColoredPoint-y thePoint) (ColoredPoint-color thePoint)) =>5 6 black Note: no Point accessors were required to manipulate the inherited fields, `x’ and `y’ from within the ColoredPoint class. ColoredPoint has accessors of its own for these fields. Whereas in Swindle it needs to written as: Swindle CLOS (defclass Point (Object) x y :auto #t :print #t) (defclass ColoredPoint (Point) color :auto #t :print #t) (define thePoint (make-ColoredPoint :x 3 :y 44 :color ‘white)) (set-Point-x! thePoint 5) (set-Point-y! thePoint 6) (set-aColoredPoint-color! thePoint ‘black) (printf “~n=>~a ~a ~a” (Point-x thePoint) (Point-y thePoint) (ColoredPoint-color thePoint)) =>5 6 black It is not a big deal to add, by hand coding accessors for the ancestor fields to the derived class. I've tried it and it works fine. However, to create a true port of Meroonet, where everything is done with macros I run into the problems of the scope of these added methods. The reason is that I necessarily have to walk a list of the ancestors and for each a list of slots and then create a pair of accessor methods for the derived class. I've yet to figure out how to succeed in walking through this list of ancestors and slots without ultimately ending definition context when not at top-level, or being forced off top-level, where the class was defined. And so I end up with a class that has top-level scope and accessor methods with some form of local scope. So my question is, am I overlooking some parameter setting of Swindle CLOS which would have it behave in the manner of Meroonet regarding ancestor accessors? If not, does someone have a germ of an idea on how to execute defmethod statements programmatically without either ending definition context or being forced off top-level, without resorting to writing the s-expressions out to a file and loading them in? <pre class="moz-signature" cols="72">Thanks, --kyle Kyle Smith airfoil at bellsouth dot net schemekeys.blogspot.comschemekeys.blogspot.com </pre> </body> </html>