record type not safely stored

record type not safely stored

[Judy Hawkins]

#|

I wanted to create records that would remain available throughout a
guile session, but they get stepped on in some way I don't know how
to fix.

See the bottom of this file for a complete guile session illustrating
the bug.

|#


(use-modules (ice-9 rdelim))

(define (wl s) (write-line s))

(define r:type (make-record-type "good-rec" '(laugh sleep)))
(define r:type? (record-predicate r:type))
(define r:constr (record-constructor r:type))

(define	 r:g:laugh (record-accessor r:type (string->symbol "laugh")))
(define	 r:s:laugh (record-modifier r:type (string->symbol "laugh")))
(define	 r:g:sleep (record-accessor r:type (string->symbol "sleep")))
(define	 r:s:sleep (record-modifier r:type (string->symbol "sleep")))


(define (make-r1)
  (let* (
	 (r1 (r:constr "giggle" "dream"))
	 )
    r1  ;;; return it so I can try to keep it around
    )
  )

(if (not (defined? (string->symbol "Keep-r1")))
    (define Keep-r1 #f))

(define (keep-record-around)
  (if (not Keep-r1)
      (set! Keep-r1 (make-r1))
      (wl "Keep-r1 already has the record"))
  )

(keep-record-around)
(wl "Good record?")
(wl (r:type? Keep-r1))
(wl Keep-r1)


#|
 guile session: load rb.scm twice, see if Keep-r1 has a valid record.

 $ guile

 guile> (load "rb.scm")
 Good record?
 #t
 #<good-rec laugh: giggle sleep: dream>

 guile> (r:g:laugh Keep-r1)
 "giggle"

 guile> (load "rb.scm")
 Keep-r1 already has the record
 Good record?
 #f
 #<good-rec laugh: giggle sleep: dream>

 guile> (r:g:laugh Keep-r1)

 ERROR: In procedure %record-type-check:
 ERROR: Wrong type record (want `"good-rec"'): #<good-rec laugh: giggle sleep: dream>
 ABORT: (wrong-type-arg)
 guile> 

 what I expected was for (r:g:laugh Keep-r1) to work fine both times.

 Other types such as strings and procedures treated the same way work
 as I expected them to.

|#


      

Re: record type not safely stored

[Ludovic Courtès]

Hi,

Judy Hawkins <jlharkins@yahoo.com> writes:

> (define r:type (make-record-type "good-rec" '(laugh sleep)))

[...]

>  guile> (load "rb.scm")
>  Good record?
>  #t
>  #<good-rec laugh: giggle sleep: dream>
>
>  guile> (r:g:laugh Keep-r1)
>  "giggle"
>
>  guile> (load "rb.scm")
>  Keep-r1 already has the record
>  Good record?
>  #f
>  #<good-rec laugh: giggle sleep: dream>
>
>  guile> (r:g:laugh Keep-r1)
>
>  ERROR: In procedure %record-type-check:
>  ERROR: Wrong type record (want `"good-rec"'): #<good-rec laugh: giggle sleep: dream>
>  ABORT: (wrong-type-arg)
>  guile> 
>
>  what I expected was for (r:g:laugh Keep-r1) to work fine both times.

That's because each load yields a `make-record-type', and the record
type created the second type has the same name as the one created the
first time but it's not `eq?' to it, hence the type mismatch.

Thanks,
Ludo'.