Package: guile;
Reported by: Alejandro Sanchez <hiphish <at> openmailbox.org>
Date: Wed, 8 Mar 2017 16:10:01 UTC
Severity: normal
Done: Andy Wingo <wingo <at> igalia.com>
Bug is archived. No further changes may be made.
Message #13 received at 26026 <at> debbugs.gnu.org (full text, mbox):
From: Alejandro Sanchez <hiphish <at> openmailbox.org> To: 26026 <at> debbugs.gnu.org Subject: Re: bug#26026: closed (Re: bug#26026: Defining a method named zero? breaks primitive zero?) Date: Sat, 22 Apr 2017 16:46:40 +0200
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This does not work. If I remove the export of ‘zero?’ I get another error: scheme@(guile-user)> (zero? (make <vector2>)) <unnamed port>:3:1: <unnamed port>:3:1: In procedure =: Wrong type: #<<vector2> 106606e20> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue. scheme@(guile-user) [1]> ,bt In current input: 3:1 0 (_) scheme@(guile-user) [1]> That is why I was exporting ‘zero?’ to begin with. I do not have to export ‘+’ or ‘-‘ for example. > On 19 Apr 2017, at 17:13, GNU bug Tracking System <help-debbugs <at> gnu.org> wrote: > > Your bug report > > #26026: Defining a method named zero? breaks primitive zero? > > which was filed against the guile package, has been closed. > > The explanation is attached below, along with your original report. > If you require more details, please reply to 26026 <at> debbugs.gnu.org. > > -- > 26026: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=26026 > GNU Bug Tracking System > Contact help-debbugs <at> gnu.org with problems > > From: Andy Wingo <wingo <at> igalia.com> > Subject: Re: bug#26026: Defining a method named zero? breaks primitive zero? > Date: 19 April 2017 at 17:12:12 GMT+2 > To: Alejandro Sanchez <hiphish <at> openmailbox.org> > Cc: 26026-done <at> debbugs.gnu.org > > > On Wed 08 Mar 2017 12:07, Alejandro Sanchez <hiphish <at> openmailbox.org> writes: > >> If I define a ‘zero?’ predicate method for a custom class the primitive ‘zero?’ is lost. Here is a simple vector module: >> >> ;;; File vector2.scm >> (define-module (vector2) >> #:use-module (oop goops) >> #:export (<vector2> get-x get-y zero?)) >> >> (define-class <vector2> () >> (x #:init-value 0 #:getter get-x #:init-keyword #:x) >> (y #:init-value 0 #:getter get-y #:init-keyword #:y) ) >> >> (define-generic zero?) >> (define-method (zero? (v <vector2>)) >> (and (zero? (get-x v)) >> (zero? (get-y v)))) >> >> In the Guile REPL try executing the following code: >> >> scheme@(guile-user)> (use-modules (oop goops) (vector2)) >> scheme@(guile-user)> (zero? (make <vector2>)) >> >> This will display >> >> WARNING: (guile-user): `zero?' imported from both (ice-9 r5rs) and (vector2) >> ERROR: In procedure scm-error: >> ERROR: No applicable method for #<<generic> zero? (1)> in call (zero? 0) >> >> Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue. >> scheme@(guile-user) [1]> ,bt >> In vector2.scm: >> 11:7 2 (_ #<<vector2> 105e87e00>) >> In oop/goops.scm: >> 1438:4 1 (cache-miss 0) >> In unknown file: >> 0 (scm-error goops-error #f "No applicable method for ~S in call ~S" (#<<gen…> …) …) >> >> Apparently the problem is that ‘zero?’ is defined in two modules and >> the vector2 definition overrides it. This isn’t the case with other >> primitives like ‘+’ or ‘*’, so this seems like a bug? I had built >> Guile from HEAD a few days ago, my package manager shows 6fff84d as >> the version number, so I guess that must be the hash of the commit >> HEAD was pointing to at that time. > > Actually the (vector2) module makes a fresh definition for zero?. You > can tell because zero? is in its export list. So instead of extending > the primitive-generic that is zero?, you are making a new definition. > See: > > scheme@(guile-user)> (define-module (foo) #:export (zero?)) > $1 = #<directory (foo) 1203c80> > scheme@(foo)> (zero? 0) > <unnamed port>:4:0: <unnamed port>:4:0: Unbound variable: zero? > > Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue. > > If you want to extend a primitive-generic, then do that by not exporting > zero?. In a way it's like mutating the primitive in place, giving it > additional powers. > > Andy > > > > > From: Alejandro Sanchez <hiphish <at> openmailbox.org> > Subject: Defining a method named zero? breaks primitive zero? > Date: 8 March 2017 at 12:07:56 GMT+1 > To: bug-guile <at> gnu.org > > > If I define a ‘zero?’ predicate method for a custom class the primitive ‘zero?’ is lost. Here is a simple vector module: > > ;;; File vector2.scm > (define-module (vector2) > #:use-module (oop goops) > #:export (<vector2> get-x get-y zero?)) > > (define-class <vector2> () > (x #:init-value 0 #:getter get-x #:init-keyword #:x) > (y #:init-value 0 #:getter get-y #:init-keyword #:y) ) > > (define-generic zero?) > (define-method (zero? (v <vector2>)) > (and (zero? (get-x v)) > (zero? (get-y v)))) > > In the Guile REPL try executing the following code: > > scheme@(guile-user)> (use-modules (oop goops) (vector2)) > scheme@(guile-user)> (zero? (make <vector2>)) > > This will display > > WARNING: (guile-user): `zero?' imported from both (ice-9 r5rs) and (vector2) > ERROR: In procedure scm-error: > ERROR: No applicable method for #<<generic> zero? (1)> in call (zero? 0) > > Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue. > scheme@(guile-user) [1]> ,bt > In vector2.scm: > 11:7 2 (_ #<<vector2> 105e87e00>) > In oop/goops.scm: > 1438:4 1 (cache-miss 0) > In unknown file: > 0 (scm-error goops-error #f "No applicable method for ~S in call ~S" (#<<gen…> …) …) > > Apparently the problem is that ‘zero?’ is defined in two modules and the vector2 definition overrides it. This isn’t the case with other primitives like ‘+’ or ‘*’, so this seems like a bug? I had built Guile from HEAD a few days ago, my package manager shows 6fff84d as the version number, so I guess that must be the hash of the commit HEAD was pointing to at that time. > > >
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