What do people use for type verification in the instance hierarchy?
That is, given:
(define-class <a> ()
(...))
(define-class <b> ()
(...))
(define-class <x> (<a> <b>)
(...))
I want a function isa? which has the following behavior:
(isa? <x> (make <x>) -> #t
(isa? <a> (make <x>) -> #t
(isa? <b> (make <x>) -> #t
(isa? <x> (make <a>) -> #f
(isa? <a> (make <a>) -> #t
(isa? <b> (make <a>) -> #f
(isa? <x> (make <b>) -> #f
(isa? <a> (make <b>) -> #f
(isa? <b> (make <b>) -> #t
anything else is #f
I'm writing one using instance?, class-of, class-name and
class-direct-supers. This seems the most straightforward way, but I
wondered if I was missing something.
Received on Sat Jan 06 1996 - 02:37:32 CET