From: David Kastrup <dak@gnu.org>
To: emacs-devel@gnu.org
Subject: Re: HELP, PLEASE! Syntax problem!
Date: Fri, 27 Nov 2009 10:56:34 +0100 [thread overview]
Message-ID: <87d434qoj1.fsf@lola.goethe.zz> (raw)
In-Reply-To: 20091127091607.GA3245@muc.de
Alan Mackenzie <acm@muc.de> writes:
> On Fri, Nov 27, 2009 at 12:48:33AM +0900, Stephen J. Turnbull wrote:
>> Alan Mackenzie writes:
>
>> > Just as a matter of interest (ha!) Stephen, does XEmacs have an
>> > equivalent to the 'category text property?
>
>> No.
>
> That's a shame.
>
>> I'm not sure how much farther you can push that kind of thing, but
>> clearly it works for you now.
>
> Well, for one thing, rather than just having the 'category property,
> you could allow any property to be made "categorical". Then you could
> introduce all sorts of rules as to which "categorical" property
> prevails when several have conflicting settings of a particular
> property. ... ;-)
>
> But, as RMS would undoubtedly say, there doesn't seem to be any need
> for such an "advanced" feature.
>
>> Eventually I guess we'll have to match the Emacs API, but we don't have
>> it now.
>
> It's more than an API: it's a fundamental feature. Without it, the
> only way to change a text property on ALL characters of some class is
> to scan through the buffer, which would be unacceptably slow for what
> I need to do.
>
> So, yes, please feel free to get it implemented in XEmacs!
You are underestimating XEmacs. It has a function iterating over all
extents (their equivalent of both overlays and text properties) in a
half-/open/closed range that have a particular set or state of
properties. So you can say something like "give me all extents for
which the property 'category happens to be 'text".
Something like
(map-extents (lambda (extent) ...) some-flag (point-min)
(point-max) another-flag and-yet-another 'category 'text)
You'll be brooding two hours over the documentation of this function,
experiment another half an hour, and you are there.
XEmacs calls something "API" comparable to a mathematician calling a
proof "trivial". Mostly synonymous with "possible".
Just because XEmacs has a single concept and a single work function for
something does not mean that it can't be made to do a hundred things.
You'll be muttering bad things through your teeth whenever you are
reduced to reverting to map-extents.
But it is there. And it does almost any job.
--
David Kastrup
next prev parent reply other threads:[~2009-11-27 9:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-25 12:58 HELP, PLEASE! Syntax problem! Alan Mackenzie
2009-11-25 14:43 ` Stefan Monnier
2009-11-25 20:30 ` Alan Mackenzie
2009-11-25 21:45 ` Stefan Monnier
2009-11-25 22:13 ` Alan Mackenzie
2009-11-26 0:12 ` Stephen J. Turnbull
2009-11-26 8:53 ` Alan Mackenzie
2009-11-26 15:48 ` Stephen J. Turnbull
2009-11-27 9:16 ` Alan Mackenzie
2009-11-27 9:56 ` David Kastrup [this message]
2009-11-27 10:44 ` Alan Mackenzie
2009-11-27 8:16 ` A Soare
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