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bug#37066: Using GOOPS #:allocation #:virtual slot option causes stack o
From: |
David Pirotte |
Subject: |
bug#37066: Using GOOPS #:allocation #:virtual slot option causes stack overflow |
Date: |
Sun, 18 Aug 2019 05:08:53 -0300 |
Hello Jan,
> I've written the program attached below and it hangs at writing
> "after changing (K): ", computer freezes for a moment and then Guile
> throws the following message:
> allocate_stack failed: Can't allocate memory
> Warning: Unwind-only `stack-overflow' exception; skipping pre-unwind
> handler.
> ...
This is not goops bug. The problem occurs because you try to set the
value of the virtual slot, something you should never do. Here is a
slightly corrected version of your code:
(define-module (temperature)
#:use-module (oop goops)
#:export (<temperature>
kelvin
celsius))
(define-class <temperature> ()
(k #:accessor kelvin
#:init-keyword #:k
#:init-value 0)
(c #:accessor celsius
#:init-keyword #:c
#:allocation #:virtual
#:slot-ref (lambda (o)
(- (kelvin o) 273.15))
#:slot-set! (lambda (o c)
(set! (kelvin o) (+ 273.15 c)))))
Then, in a repl:
scheme@(guile-user)> (add-to-load-path "/your/temperature/module/path")
scheme@(guile-user)> ,use (oop goops)
scheme@(guile-user)> ,use (oop goops describe)
scheme@(guile-user)> ,use (temperature)
;;; note: source file ... newer than compiled ...
;;; ...
scheme@(guile-user)> (make <temperature>)
$2 = #<<temperature> 5604c4614200>
scheme@(guile-user)> (describe $2)
#<<temperature> 5604c4614200> is an instance of class <temperature>
Slots are:
k = 0
c = -273.15
scheme@(guile-user)> (set! (celsius $2) 0)
$3 = 273.15
scheme@(guile-user)> (describe $2)
#<<temperature> 5604c4614200> is an instance of class <temperature>
Slots are:
k = 273.15
c = 0.0
> ... it also throws a different error ...
I didn't look into this manual example code yet, I wanted to get back
to your own example first ...
David
pgp3Q7jJ3KQkK.pgp
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