[debbugs-tracker] bug#10190: closed (eventp can give incorrect results (subr.el), Emacs 23 and 24)

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Your message dated Thu, 19 Jul 2012 02:25:19 -0400
with message-id <address@hidden>
and subject line Re: bug#10190: eventp can give incorrect results (subr.el), 
Emacs 23 and 24
has caused the debbugs.gnu.org bug report #10190,
regarding eventp can give incorrect results (subr.el), Emacs 23 and 24
to be marked as done.

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10190: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10190
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> --- Begin Message ---
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> Subject: 
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> eventp can give incorrect results (subr.el), Emacs 23 and 24
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> Date: 
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> Fri, 2 Dec 2011 00:55:11 -0500
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> This is not a major problem, but it did come up for me in a real program.
> In Emacs 23 and 24, the function eventp in subr.el can give incorrect results
> for symbolic events, depending on the timing of the call.  This seems to
>
> occurs because event symbol elements (mask, modifiers, basic type) are stored in a plist
> associated with symbolic events, but the list is set in the function
> internal-event-symbol-parse-modifiers, which is only called in the function
>
> event-modifiers not in the inline function eventp.  Hence, code that tests for
> an event before checking the modifiers can give the wrong results, e.g.,
>
>            (cond  ((integerp c) ...)  
>                        ....
>
>                       ((eventp )  (do-something-with (event-modfiers c)))
>                       (t
>                           (not-what-we-want-with c)))
>
> will fail when c is a symbolic event that has not been parsed before.
>
> Consider the following sequence, which illustrates the error in a new Emacs 24
> session with -Q (on Mac OS X 10.5.8). Although the event M-S-f5 is a rather
> obscure one, it is the event used to illustrate the event- fucntions in the
>
> Elisp Info documentation.
>
> ;; #1
> (eventp 'M-S-f5)
> > nil
> (symbol-plist 'M-S-f5)
> > nil
>
> ;; #2
> (event-modifiers 'M-S-f5)
> > (meta shift)
>
> ;; #3
> (eventp 'M-S-f5)
>
> > (f5 meta shift)
> (symbol-plist 'M-S-f5)
> > (event-symbol-element-mask (f5 167772160) event-symbol-elements (f5 meta shift))
>
> A similar example occurs with, say, M-s-z, even if M-s-z has been defined in the global map.
>
> This problem holds with event-basic-type too because it also just checks the symbol plist.  
> In #1, for instance, (event-basic-type 'M-S-f5) would be nil, but not in #3.  
> Another side of the problem(?) is that in #1  calling (event-modifier 'foobar) would make
>
>
> subsequent (eventp 'foobar) calls true. 
>
> Neither of these seems like desirable behaviors. 
>
> Not a really big deal, but I thought I'd pass it along.
>
> Thanks,
>
>    Chris
>
> P.S. I  haven't had a chance to look over the C code on this too closely, but the function
>
>
> parse_modifiers, which is doing the work in internal-event-symbol-parse-modifiers,
> is called at some points when reading key sequences. Caching the events when
> they are read would seem to be a good idea, although it is not happening in the
> M-s-z example. 
>
>
> --- End Message ---
> --- Begin Message ---
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> Subject: 
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> Re: bug#10190: eventp can give incorrect results (subr.el),	Emacs 23 and 24
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>
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> Date: 
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> Thu, 19 Jul 2012 02:25:19 -0400
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/24.1.50 (gnu/linux)
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>
>
> > My own impression is that the patch below would be an improvement, but
> > I'd rather keep it for after 24.1.
>
> Installed (in a slightly different form).
>
>
>         Stefan
>
>
> --- End Message ---