GNU bug report logs - #15117
24.3.50; doc of `(forward|backward)-*': state return value

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Message #82 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
To: bug-gnu-emacs <at> gnu.org
Cc: Drew Adams <drew.adams <at> oracle.com>
Subject: Re: bug#15117: 24.3.50; doc of `(forward|backward)-*': state return
 value
Date: Tue, 11 Feb 2014 19:42:52 +0100

Am 11.02.2014 18:29, schrieb Drew Adams:
>> If you (Drew) want that something productive comes out of this,
>> please point out specific forward/backward-* functions that return
>> non-trivial values, and those values are not documented.  The only 2
>> functions mentioned since the beginning of this discussion are
>> forward/backward-sexp, which always return nil, a.k.a. "nothing".  I
>> also tried a couple of other random functions, and they seem all to
>> be of this "nothing" kind.  So I wonder whether we have any real
>> problem here.
>
> I would like to see functions that are purely motion functions
> return `point', the destination position, unless there is a more
> useful return value (as is already the case for a function such as
> `forward-comment' or `forward-button').
>
> IOW, some useful value is better than none.  Note: I have nothing
> against picking a _more_ useful value than `point'.  Point is just
> a default suggestion.  For an example of a more useful value, see
> `forward-comment': it sets `point' but returns t or nil.

IMO these functions should return point if successful, i.e. if point was moved, but nil otherwise, for example at EOB.
As point --a number-- evals to `t', a respective check might be set upon from receiving function.

>
> And document that return value.  Here are some candidates, for a
> start (likewise, their backward relatives, and other relatives,
> such as `up-list', `down-list', `backward-up-list'...).
>
> forward-char
> forward-list ; already returns `point'
> forward-page ; returns count
> forward-same-syntax
> forward-sentence
> forward-sexp
> forward-symbol
> forward-thing
> forward-to-indentation
> forward-visible-line
> forward-whitespace
> forward-word
>
> We can look for other motion functions to treat similarly after
> this start.  Assuming there is any will to do this.
>
>
>
>

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