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Re: How about text-property-functions using `equal' rather than `eq'?
From: |
David Kastrup |
Subject: |
Re: How about text-property-functions using `equal' rather than `eq'? |
Date: |
Tue, 05 Feb 2008 09:48:38 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.0.50 (gnu/linux) |
Richard Stallman <address@hidden> writes:
> All the built in text property functions which compare properties appear
> to use `eq' for the comparison. Some of these actually say this in
> their doc-strings or the pertinent manual page, some of them might
> actually say it in both. ;-(
>
> `eq' is faster,
More importantly, it is constant time.
> I would dearly love to use text-property-any to locate such a
> buffer position, but unfortunately (eq '(1) '(1)) => nil. :-( So
> I've had to code up a clumsy equivalent which will certainly be
> much slower.
>
> You can write code which uses the primitives to find the next non-eq
> property, then comparing it with equal and looping so that you find
> the next non-equal property.
One can also see where the constant '(1) is created and keep a copy of
that for eq-comparison.
--
David Kastrup