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Re: using empty_string as the only "" string

From: David Kastrup
Subject: Re: using empty_string as the only "" string
Date: Fri, 27 Apr 2007 12:29:11 +0200
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.98 (gnu/linux)

Dmitry Antipov <address@hidden> writes:

> Richard Stallman wrote:
>>     Also note that canonicalization of null strings assumes that
>>     non-null interval can't be attached to empty string regardless of
>>     it's multibyteness (at a first glance, this is how the stuff ticks
>>     now, but I'm not sure about this).
>> Alas, I don't understand those words.
> Is it possible that STRING_INTERVALS(s) is not NULL if 's' is an empty string,
> unibyte or multibyte ? I believe no (at least, 'set-text-properties' can't
> attach properties to empty string).
> Otherwise it would be nearly impossible to canonicalize empty
> strings since each empty string may have unique intervals.

Buffers have overlays (and text), strings merely have text and that
text can have text properties on characters.

If an empty string contains either, it would appear to be a bug.
Things are different in XEmacs, where both are represented by
"extents" which can be empty in strings, too.

David Kastrup, Kriemhildstr. 15, 44793 Bochum

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