Interactive hat. [Was: CUA-like stuff spuriously enables transient-mark-mode]

[Alan Mackenzie]

Hi, Stefan,

On Tue, Mar 24, 2009 at 09:38:29PM -0400, Stefan Monnier wrote:
> >> Where do you see it hardcoded in the command loop?

> > In Fcall_interactively, Lines 207 and 231, where it is interpreting the
> > interactive string:

> >       else if (*string == '^')
> >         {
> >           if (! NILP (Vshift_select_mode))
> >              call1 (Qhandle_shift_selection, Qnil);    <================
> >           /* Even if shift-select-mode is off, temporarily active
> >              regions could be set using the mouse, and should be
> >              deactivated.  */
> >           else if (CONSP (Vtransient_mark_mode)
> >                    && EQ (XCAR (Vtransient_mark_mode), Qonly))
> >             call1 (Qhandle_shift_selection, Qt);       <================
> >           string++;
> >         }
> > .

> I see.  I guess we just disagree on what is meant by "hardcoded in the
> command loop": this code is explicitly requested by the "^" code in the
> `interactive' string of a command, so it seems (to me) pretty far from
> "hardcoded in the command loop".

It's hard-coded to the shift-key, rather than using the normal Emacs
mechanism of putting the "shifted" versions of movement commands into a
minor mode map.  Interactive strings which use "^" are incompatible with
other Emacs versions.  This will cause problems.

How is an external library writer going to use the interactive "^"?
Assuming that the library should also work under XEmacs and Emacs 22,
just using the "^" won't work; an interactive string with "^" throws an
error in Emacs 22.

The next try is to use a macro which will generate an appropriate
interactive string.  Something like:
    
    (defmacro foo-interactive (s-22 s-23)
       "doc string"
       `(interactive ,(if (emacs-got-interactive-hat) s-23 s22)))

, but I can't get defun to take a macro-generated interactive string.  I
suspect it's not possible.  It seems to work, sort of, in byte-compiled
defuns.

Could we supply some sort of macro which will add "^" to an interactive
string?  Then at least each external library author won't have to figure
it out himself.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).