bug#7470: 24.0.50; Word Isearch lazy highlighting

bug#7470: 24.0.50; Word Isearch lazy highlighting

[Dani Moncayo]

Hi,

Please, consider the situation arising after performing these steps::
0) Start Emacs (emacs -Q).
1) Go to the beginning of the *scratch* buffer (M-<).
2) Start an incremental _word_ search (M-s w).
3) Type `that fil'.

After step 3, the second occurrence of `that fil' should be
highlighted with `lazy-highlighting' face [1], but that doesn't
happen.

--------------

[1] Emacs Manual. Section "13.3 Word Search" (node "Word Search").
Last paragraph:
>   A nonincremental word search differs slightly from the incremental
> version in the way it finds a match: the last word in the search string
> must be an exact match for a whole word.  In an incremental word
> search, the last word in the search string can match part of a word;
> this allows the matching to proceed incrementally as you type.

-- 
Dani Moncayo

bug#7470: 24.0.50; Word Isearch lazy highlighting

[Juri Linkov]

> Please, consider the situation arising after performing these steps::
> 0) Start Emacs (emacs -Q).
> 1) Go to the beginning of the *scratch* buffer (M-<).
> 2) Start an incremental _word_ search (M-s w).
> 3) Type `that fil'.
>
> After step 3, the second occurrence of `that fil' should be
> highlighted with `lazy-highlighting' face [1], but that doesn't
> happen.

The task of the word search is to find and highlight complete words.
The heuristics it applies with partial lax word search (comparing
the current search string with the previous one in `isearch-search-fun')
is to help the user to type the complete word search string
without signaling an error.  So I doubt that lazy highlighting should
follow the same logic as partial lax word search.

What does lazy highlighting try to tell the user: "Look, if you type
C-s, then Isearch will land in the next highlighted place".  But in case of
incomplete word search this is not true.  When the user types C-s,
it will not stop at the partial word string highlighted as you suggested.

bug#7470: 24.0.50; Word Isearch lazy highlighting

[Dani Moncayo]

On Wed, Nov 24, 2010 at 02:43, Juri Linkov <juri@jurta.org> wrote:
>
> The task of the word search is to find and highlight complete words.
> The heuristics it applies with partial lax word search (comparing
> the current search string with the previous one in `isearch-search-fun')
> is to help the user to type the complete word search string
> without signaling an error.  So I doubt that lazy highlighting should
> follow the same logic as partial lax word search.
>
> What does lazy highlighting try to tell the user: "Look, if you type
> C-s, then Isearch will land in the next highlighted place".  But in case of
> incomplete word search this is not true.  When the user types C-s,
> it will not stop at the partial word string highlighted as you suggested.
>

I understand and agree with your reasoning, and I think would be good
to include that idea in the section of the manual that I quoted
before. The way it is worded now seems a bit misleading/incomplete to
me.

Thank you very much.

-- 
Dani Moncayo

bug#7470: 24.0.50; Word Isearch lazy highlighting

[Chong Yidong]

Dani Moncayo <dmoncayo@gmail.com> writes:

> I understand and agree with your reasoning, and I think would be good
> to include that idea in the section of the manual that I quoted
> before. The way it is worded now seems a bit misleading/incomplete to
> me.

I've changed the manual text to reflect this.  Thanks.