* (fset 'nil 'message)
@ 2018-05-11 2:30 rslovers
2018-05-11 12:39 ` Noam Postavsky
[not found] ` <mailman.13637.1526042360.27995.help-gnu-emacs@gnu.org>
0 siblings, 2 replies; 4+ messages in thread
From: rslovers @ 2018-05-11 2:30 UTC (permalink / raw
To: help-gnu-emacs
Greetings, emacs community:
Today I accidentally ran (fset 'nil 'message), after that multiple
functions like forward-word, kill-word stopped working, and complained
that `Symbol’s function definition is void: nil'.
After (fset 'nil 'nil) they started working again, does anybody undertand
what is going on here?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: (fset 'nil 'message)
2018-05-11 2:30 (fset 'nil 'message) rslovers
@ 2018-05-11 12:39 ` Noam Postavsky
2018-05-13 7:09 ` rslovers
[not found] ` <mailman.13637.1526042360.27995.help-gnu-emacs@gnu.org>
1 sibling, 1 reply; 4+ messages in thread
From: Noam Postavsky @ 2018-05-11 12:39 UTC (permalink / raw
To: rslovers; +Cc: Help Gnu Emacs mailing list
On 10 May 2018 at 22:30, <rslovers@yandex.com> wrote:
> Today I accidentally ran (fset 'nil 'message), after that multiple
> functions like forward-word, kill-word stopped working, and complained
> that `Symbol’s function definition is void: nil'.
>
> After (fset 'nil 'nil) they started working again, does anybody undertand
> what is going on here?
Yes, after you do (fset 'nil 'message), (functionp nil) returns t, but
(funcall nil) still fails. Many places do things like
(when (functionp some-var)
(funcall some-var))
which will cause the errors you see if `some-var' is nil.
In Emacs 26, doing (fset 'nil 'message) will fail (see Bug#25110).
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25110
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: (fset 'nil 'message)
[not found] ` <mailman.13637.1526042360.27995.help-gnu-emacs@gnu.org>
@ 2018-05-11 14:58 ` Barry Margolin
0 siblings, 0 replies; 4+ messages in thread
From: Barry Margolin @ 2018-05-11 14:58 UTC (permalink / raw
To: help-gnu-emacs
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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In article <mailman.13637.1526042360.27995.help-gnu-emacs@gnu.org>,
Noam Postavsky <npostavs@gmail.com> wrote:
> On 10 May 2018 at 22:30, <rslovers@yandex.com> wrote:
>
> > Today I accidentally ran (fset 'nil 'message), after that multiple
> > functions like forward-word, kill-word stopped working, and complained
> > that `Symbol’s function definition is void: nil'.
> >
> > After (fset 'nil 'nil) they started working again, does anybody undertand
> > what is going on here?
>
> Yes, after you do (fset 'nil 'message), (functionp nil) returns t, but
> (funcall nil) still fails. Many places do things like
>
> (when (functionp some-var)
> (funcall some-var))
>
> which will cause the errors you see if `some-var' is nil.
>
> In Emacs 26, doing (fset 'nil 'message) will fail (see Bug#25110).
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25110
This brings back memories. Several decades ago I worked for a company
that used Symbolics Lisp Machines, and one of our applications had a bug
that did something like (set 'nil <something>). This crashed the
operating system. Turns out that the software checked for this in SETQ,
but not SET.
Symbolics put the value cells of NIL and T into non-writable memory in
the next release.
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: (fset 'nil 'message)
2018-05-11 12:39 ` Noam Postavsky
@ 2018-05-13 7:09 ` rslovers
0 siblings, 0 replies; 4+ messages in thread
From: rslovers @ 2018-05-13 7:09 UTC (permalink / raw
To: help-gnu-emacs
On Fri, May 11, 2018 at 08:39:16AM -0400, Noam Postavsky wrote:
> Yes, after you do (fset 'nil 'message), (functionp nil) returns t, but
> (funcall nil) still fails. Many places do things like
>
> (when (functionp some-var)
> (funcall some-var))
>
> which will cause the errors you see if `some-var' is nil.
>
> In Emacs 26, doing (fset 'nil 'message) will fail (see Bug#25110).
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25110
Thanks, appreciate the info.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-05-13 7:09 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-05-11 2:30 (fset 'nil 'message) rslovers
2018-05-11 12:39 ` Noam Postavsky
2018-05-13 7:09 ` rslovers
[not found] ` <mailman.13637.1526042360.27995.help-gnu-emacs@gnu.org>
2018-05-11 14:58 ` Barry Margolin
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