Hi there!
I found this while writing some code for work earlier (I'm lucky enough to
be able to write testing programs in the language of my choice). I define a
class and a generic method in a module in a file, then load it into the
REPL. I can make an instance of that class, binding it to a variable at the
toplevel, and use the generic method just fine. If I then reload my code, I
cannot use the generic method with the bound instance: I get the "no method
defined for given argument classes" error. If my class and generic method
definitions are not in a module, everything works fine. I'm wondering if
this is me misunderstanding something, or it is intentional behaviour, or
maybe it's a bug. Here is a concrete example:
;; FILE: coops-test-1.scm
(define-class <a-class> (<standard-object>)
((a 2) (b 3)))
(define-method (lols (instance <a-class>))
(+ (slot-value instance 'a) (slot-value instance 'b)))
;; FILE: coops-test-2.scm
(module foo
(<a-class>
lols)
(import scheme chicken coops)
(define-class <a-class> (<standard-object>)
((a 2) (b 3)))
(define-method (lols (instance <a-class>))
(+ (slot-value instance 'a) (slot-value instance 'b)))
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#;1> (use coops)
; loading /opt/chicken/lib/chicken/5/coops.import.so ...
; loading /opt/chicken/lib/chicken/5/scheme.import.so ...
; loading /opt/chicken/lib/chicken/5/chicken.import.so ...
; loading /opt/chicken/lib/chicken/5/matchable.import.so ...
; loading /opt/chicken/lib/chicken/5/srfi-1.import.so ...
; loading /opt/chicken/lib/chicken/5/data-structures.import.so ...
; loading /opt/chicken/lib/chicken/5/extras.import.so ...
; loading /opt/chicken/lib/chicken/5/record-variants.import.so ...
; loading /opt/chicken/lib/chicken/5/foreign.import.so ...
; loading /opt/chicken/lib/chicken/5/coops.so ...
#;2> (load "coops-test-1.scm")
; loading coops-test-1.scm ...
Note: implicitly defining generic-procedure: lols
#;3> (define instance (make <a-class>))
#;4> (lols instance)
5
#;5> (load "coops-test-1.scm")
; loading coops-test-1.scm ...
#;6> (lols instance)
5
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#;1> (use coops)
; loading /opt/chicken/lib/chicken/5/coops.import.so ...
; loading /opt/chicken/lib/chicken/5/scheme.import.so ...
; loading /opt/chicken/lib/chicken/5/chicken.import.so ...
; loading /opt/chicken/lib/chicken/5/matchable.import.so ...
; loading /opt/chicken/lib/chicken/5/srfi-1.import.so ...
; loading /opt/chicken/lib/chicken/5/data-structures.import.so ...
; loading /opt/chicken/lib/chicken/5/extras.import.so ...
; loading /opt/chicken/lib/chicken/5/record-variants.import.so ...
; loading /opt/chicken/lib/chicken/5/foreign.import.so ...
; loading /opt/chicken/lib/chicken/5/coops.so ...
#;2> (load "coops-test-2.scm")
; loading coops-test-2.scm ...
Note: implicitly defining generic-procedure: lols
#;3> (import foo)
#;4> (define instance (make <a-class>))
#;5> (lols instance)
5
#;6> (load "coops-test-2.scm")
; loading coops-test-2.scm ...
Note: implicitly defining generic-procedure: lols
#;7> (lols instance)
Error: (lols) no method defined for given argument classes: (#<coops
standard-class `<a-class>'>)
Call history:
<syntax> (lols instance)
<eval> (lols instance) <--
I'm using Chicken 4.6.1 (git 7ac10a2fb9b04d114af97d8c9918bffae38cc534) on
Linux AMD64 with COOPS 0.8 to test this. I notice that you get the warning
about automatically defining the generic method twice, at each load, maybe
that's indicative of the problem? Is there a way to make this work? Thanks.
--
Taylor C. Venable
http://metasyntax.net/
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