Re: isearch-allow-move [Was: isearch-allow-prefix]

[Alan Mackenzie]

Hi, Juri.

On Thu, Jun 06, 2013 at 09:07:34AM +0300, Juri Linkov wrote:
> > OK, I've committed it.

> Thank you, Alan.

> Let me reuse your excellent design and create a similar option
> `isearch-allow-move' that is like `isearch-allow-scroll' but
> instead of scrolling commands it affects point motion commands
> to yank text as you go.

> So typing `C-f' will pull the next char from the buffer and add it
> to the search string, `M-f' - next word, `C-M-f' - next expression,
> `M-}' - next paragraph, `C-e' - next line, and so on.

I can't help feeling there will be excessively complicated interactions
here, somewhere.

I'm assuming that backward commands like C-b won't be included.  But what
does it mean to C-f with a prefix arg of -1?  Does it mean "remove the
last char from the search string"?  If not, why not?  Or maybe a negative
prefix argument would cause the command to be ignored.

Or maybe C-b would be allowed here to remove the last char from the
search string.  You could then use it to erase the entire search string
and then convert a forward search into backward search by another C-b.
Maybe.

Maybe I'm just being a bit conservative, but I can foresee there being
more complications here than would make the implementation worthwhile.

> Definitely `isearch-allow-move' should be nil by default,
> and I doubt that many users might want to enable it since
> it's more useful when motion commands exit Isearch.

> But to make this feature available regardless of the value of
> `isearch-allow-move' it could be activated temporarily by the
> keymap `M-s' to allow key sequences like `M-s C-f M-f C-M-f C-e'
> that is implemented by this patch:

(Apologies for not having read the patch in full detail.)

-- 
Alan Mackenzie (Nuremberg, Germany).