RE: `isearch-allow-scroll' - a misnomer and a bad design

["Drew Adams" <drew.adams@oracle.com>]

>     I don't think there will be any inconvenience at all.  
>     Unless the user sets the option, isearch will behave
>     exactly as it has done.
>
> If the default is the current behavior, I guess the other
> option can't hurt.

As a famous person is wont to say, why not poll the users about the default
behavior?

We can at least discuss it here.  (But the important thing is of course to give
users the option.)

Unlike Richard, I am in favor of passing `C-u' through (e.g. to a command on
`isearch-mode-map') by default, that is, _not_ making it exit Isearch.  Yes,
that would be a change from past behavior.

It would have the advantage that a library can bind a command in
`isearch-mode-map', and its users need not customize the new Isearch option in
order to let that command receive `C-u' during Isearch.  They would not need to
customize anything - the command/key would just work as advertised, including
wrt a prefix arg.

Users of such a library/command have presumably already made the choice to use
it.  Why should the library have to add to the command's doc that if you want to
use a prefix argument with it (in Isearch) then you have to customize option
`isearch-blah'?

Where else do we not allow a command on a keymap to see a prefix arg used with
its key?  Why should this not be the default behavior for Isearch, too?

To me, this is all the more important because, as some have pointed out in the
past, `isearch-mode-map' is already pretty full.  Letting a command bound in
that map use a prefix arg has the effect of putting multiple commands on the
same key, distinguished by the prefix arg.  That's a good thing.

I suspected from the beginning that Richard might want `C-u' to exit Isearch (he
has indicated before that he generally likes Control keys to exit), which is why
I proposed making the behavior fix optional.

Until Richard spoke up, my impression was that the consensus of those speaking
about the issue seemed to be to let `C-u' pass through (not exit Isearch), by
default.  Maybe, maybe not.  At any rate, Alan's first patch presumably tried to
implement that behavior (without any user choice), but when he added the option
in his second patch, he made the default behavior exit Isearch.

It should still be an open question, so far, what the default behavior will be.
The only arguments I've seen are (a) what I say above versus (b) tradition (no
change in the default behavior).  That is essentially (a) providing consistency
with other keymaps versus (a) keeping the same inconsistency we've enjoyed in
the past.

Any other arguments wrt the default value?