bug#31061: 27.0.50; next-page of page-ext non-functional in dired

[Marco Wahl <marcowahlsoft@gmail.com>]

Noam Postavsky <npostavs@gmail.com> writes:

> Marco Wahl <marcowahlsoft@gmail.com> writes:
>
>> I found that with your suggestion next-page with negative argument goes
>> back one page too much in a dired buffer, though.
>>
>> I further think that the core of the irritation is that `narrow-to-page'
>> does not narrow to the following page when on the start of the '\n\n'
>> page-separator (unlike for the usual '^^L' separator).
>
> As far as I can tell, narrow-to-page still has the same problem with the
> default "\n\f" separator as the "\n\n" one.  It's just that the problem
> is more visually obvious in the dired case.  Using thingatpt seems to
> work better (but this doesn't handle the COUNT argument for
> narrow-to-page):
>
>     (let ((bounds (bounds-of-thing-at-point 'page)))
>       (narrow-to-region (car bounds) (cdr bounds)))
>
> Though I guess it might be arguable whether the page separator should
> count as part of the page or not.  The above expression (and
> `mark-page') treat the separator as part of the preceding page,
> `narrow-to-page' seems to exclude the separator from the page.

I fully agree that one might like the separator to be part of the page.
This might help e.g. for killing and yanking.

Actually I tend towards excluding any separator when narrowing to a
page.  I see a document as sequence like

<content><separator><content><separator>...<separator><content>

and the content is all I'd expect when narrowing to a page.

>> Starting with your fix I propose this modification of the else part:
>>
>>     (while (and (< count 1) (not (bobp)))
>>       (if (re-search-backward page-delimiter nil t)
>>           (when (= count 0)
>>               (goto-char (match-end 0)))
>>         (goto-char (point-min)))
>>       (setq count (1+ count)))
>>
>> This is: go to the end of the delimiter when the final page has been
>> reached.
>
> Yeah, that works.

Cool.

Best regards!