bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Drew Adams]

emacs -Q
 
Try evaluating either of these examples from (elisp) Defining Minor
Modes:
 
(define-minor-mode hungry-mode
       "Toggle Hungry mode.
     With no argument, this command toggles the mode.
     Non-null prefix argument turns on the mode.
     Null prefix argument turns off the mode.
 
     When Hungry mode is enabled, the control delete key
     gobbles all preceding whitespace except the last.
     See the command \\[hungry-electric-delete]."
      ;; The initial value.
      nil
      ;; The indicator for the mode line.
      " Hungry"
      ;; The minor mode bindings.
      '(("\C-\^?" . hungry-electric-delete))
      :group 'hunger)
 
(define-minor-mode hungry-mode
       "Toggle Hungry mode.
     With no argument, this command toggles the mode.
     Non-null prefix argument turns on the mode.
     Null prefix argument turns off the mode.
 
     When Hungry mode is enabled, the control delete key
     gobbles all preceding whitespace except the last.
     See the command \\[hungry-electric-delete]."
      ;; The initial value.
      :init-value nil
      ;; The indicator for the mode line.
      :lighter " Hungry"
      ;; The minor mode bindings.
      :keymap
      '(("\C-\^?" . hungry-electric-delete)
        ("\C-\M-\^?"
         . (lambda ()
             (interactive)
             (hungry-electric-delete t))))
      :group 'hunger)
 
Both raise this error:
 
Debugger entered--Lisp error: (error "Invalid modifier in string")
 

In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2010-05-23 on G41R2F1
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags -Ic:/xpm/include'
 

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Juanma Barranquero]

On Wed, Jun 2, 2010 at 23:42, Drew Adams <drew.adams@oracle.com> wrote:

> Debugger entered--Lisp error: (error "Invalid modifier in string")

I've fixed it using C-delete and C-M-delete (which are clearer anyway)
in the examples.

    Juanma

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Sven Joachim]

On 2010-07-27 03:38 +0200, Juanma Barranquero wrote:

> On Wed, Jun 2, 2010 at 23:42, Drew Adams <drew.adams@oracle.com> wrote:
>
>> Debugger entered--Lisp error: (error "Invalid modifier in string")
>
> I've fixed it using C-delete and C-M-delete (which are clearer anyway)
> in the examples.

C-M-delete is not the most fortunate choice since it can induce a reboot
on some systems (e.g. on the GNU/Linux console or on MS-DOS).  On
Windows, it invokes the task manager IIRC.

Sven

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Štěpán Němec]

Juanma Barranquero <lekktu@gmail.com> writes:

> On Wed, Jun 2, 2010 at 23:42, Drew Adams <drew.adams@oracle.com> wrote:
>
>> Debugger entered--Lisp error: (error "Invalid modifier in string")
>
> I've fixed it using C-delete and C-M-delete (which are clearer anyway)
> in the examples.

I'm not sure if you intended to preserve the key binding, let me just
point out that ^? (which was in the original example) is (ASCII) DEL,
i.e. usually [backspace], not [delete] on (modern?) text terminals.

Štěpán

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Juanma Barranquero]

On Tue, Jul 27, 2010 at 06:44, Sven Joachim <svenjoac@gmx.de> wrote:

> C-M-delete is not the most fortunate choice since it can induce a reboot
> on some systems (e.g. on the GNU/Linux console or on MS-DOS).  On
> Windows, it invokes the task manager IIRC.

I agree. I didn't want to change the documentation, just fix the bug.

    Juanma

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Juanma Barranquero]

On Tue, Jul 27, 2010 at 13:26, Štěpán Němec <stepnem@gmail.com> wrote:

> I'm not sure if you intended to preserve the key binding, let me just
> point out that ^? (which was in the original example) is (ASCII) DEL,
> i.e. usually [backspace], not [delete] on (modern?) text terminals.

The docstring for the sample minor mode says "the control delete key",
and my DEL key returns delete. If there's a more apropriate key
binding that does not reproduce the bug, it's fine by me.

    Juanma

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Štěpán Němec]

Juanma Barranquero <lekktu@gmail.com> writes:

> On Tue, Jul 27, 2010 at 13:26, Štěpán Němec <stepnem@gmail.com> wrote:
>
>> I'm not sure if you intended to preserve the key binding, let me just
>> point out that ^? (which was in the original example) is (ASCII) DEL,
>> i.e. usually [backspace], not [delete] on (modern?) text terminals.
>
> The docstring for the sample minor mode says "the control delete key",
> and my DEL key returns delete. If there's a more apropriate key
> binding that does not reproduce the bug, it's fine by me.

That'd be [C-backspace], if you're using the vector notation. Note we're
talking about the DEL _character_, not the key labeled Del(ete). It's
the Backspace key that usually sends DEL in the terminal (also note that
the example speaks about deleting all _preceding_ whitespace). I suspect
"the control delete key" wording comes from times when the keyboards
were somewhat different from those of today.

But it's only an example, so all this perhaps doesn't matter. I just
thought I'd mention the semantic shift introduced by the change, sorry.

  Štěpán

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Juanma Barranquero]

On Tue, Jul 27, 2010 at 19:00, Štěpán Němec <stepnem@gmail.com> wrote:

> Note we're
> talking about the DEL _character_, not the key labeled Del(ete).

The "control delete" bit on the docstring makes me think of pressing
the keys labeled Ctrl and Del, not Ctrl + Backspace...

> (also note that
> the example speaks about deleting all _preceding_ whitespace).

...but I suspect you're right. I'll change it to C-backspace /
C-M-backspace, if everybody thinks these are the right keybindings.

> But it's only an example, so all this perhaps doesn't matter. I just
> thought I'd mention the semantic shift introduced by the change, sorry.

No, thanks for bringing this up.

    Juanma

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[David De La Harpe Golden]

On 27/07/10 18:08, Juanma Barranquero wrote:


> ...but I suspect you're right. I'll change it to C-backspace /
> C-M-backspace, if everybody thinks these are the right keybindings.
>

Just noting: C-M-backspace traditionally kills an x11 server, usually 
dumping you back at a login screen when the login manager (x/g/k)dm 
respawns the server. Sometimes it's disabled these days.

bug#6334: 24.0.50; both examples in (elisp) Defining Minor Modes raise an error

[Juanma Barranquero]

On Tue, Jul 27, 2010 at 22:22, David De La Harpe Golden
<david@harpegolden.net> wrote:

> Just noting: C-M-backspace traditionally kills an x11 server,

"\C-\M-\^?" is what the original example used.

    Juanma