Add functions to C-mode?

Add functions to C-mode?

[saneman]

I would like to add/change the comment/uncomment function in the C-mode 
for emacs.

Currently it only works when a piece of text is selected and then /* */ 
is inserted.

I would like to change the function to just insert // even though some 
text might not be selected.

Is that possible?

Re: Add functions to C-mode?

[Ph. Ivaldi]

saneman wrote :

> I would like to add/change the comment/uncomment function in the
> C-mode for emacs.
> Currently it only works when a piece of text is selected and then /*
> */ is inserted.
> I would like to change the function to just insert // even though some
> text might not be selected.

I use this code but one can certainly do better:
8<------8<------8<------8<------8<------8<------8<------8<------8<------
(defun pi-?comment ()
  (interactive)
  (save-excursion
    (if mark-active
        (let ((br (region-beginning))
              (be (region-end)))
          (comment-or-uncomment-region br be)
          (indent-region br be))
      (let ((br (progn  (back-to-indentation) (point)))
            (be (progn (end-of-line) (point))))
        (comment-or-uncomment-region br be)
        (indent-according-to-mode)))))
(global-set-key (kbd "C-%") 'pi-?comment)
8<------8<------8<------8<------8<------8<------8<------8<------8<------

-- 
   Philippe Ivaldi.
http://piprim.tuxfamily.org/

Re: Add functions to C-mode?

[David Hansen]

On Sat, 19 Apr 2008 13:04:06 +0200 saneman wrote:

> I would like to add/change the comment/uncomment function in the
> C-mode for emacs.
>
> Currently it only works when a piece of text is selected and then /*
> */ is inserted.
>
> I would like to change the function to just insert // even though some
> text might not be selected.
>
> Is that possible?

M-; should do just that.  Well in c-mode it will insert /* */ if no
region is selected and will wrap the comment delimiters if the region is
active.

If you insist on "//" (which is btw not ANSI C) you have to play around
a bit with the `comment-start' and `comment-end' variables.  Not tested:

(defun cxx-comments ()
  (set (make-local-variable comment-start) "// ")
  (set (make-local-variable comment-end "")))

(add-hook c-mode-hook #'cxx-comments)

David

Re: Add functions to C-mode?

[Jason Rumney]

On Apr 19, 6:16 pm, David Hansen <david.han...@gmx.net> wrote:

> If you insist on "//" (which is btw not ANSI C)

Single line comments starting with // are part of the current ANSI and
ISO standard (C99)
.

Re: Add functions to C-mode?

[David Hansen]

On Sat, 19 Apr 2008 14:08:18 -0700 (PDT) Jason Rumney wrote:

> On Apr 19, 6:16 pm, David Hansen <david.han...@gmx.net> wrote:
>
>> If you insist on "//" (which is btw not ANSI C)
>
> Single line comments starting with // are part of the current ANSI and
> ISO standard (C99)
> .

AFAIK a standard w/o implementation.

Re: Add functions to C-mode?

[Alan Mackenzie]

Hi, Saneman!

On Sat, Apr 19, 2008 at 01:04:06PM +0200, saneman wrote:
> I would like to add/change the comment/uncomment function in the C-mode 
> for emacs.

> Currently it only works when a piece of text is selected and then /* */
> is inserted.

OK, just to check, "it" here means "M-;" (or your newly bound C-d), bound
to `comment-dwim', doesn't it?

I'm not sure about "selected" (I don't use delete-selection-mode and
stuff like that), but the "/* */" style of comments is fixed for C.
Somebody asked some while ago for a way to change this to "//", and I'm
planning to add a command to CC Mode (probably C-c C-;) in the next
release to toggle the commenting style.

> I would like to change the function to just insert // even though some 
> text might not be selected.

In the meantime, you could use the following workaround.  M-; (or your
C-d ;-) will then insert "// ".

    (defun sm-do-line-comments ()
      (setq comment-start "// ")
      (setq comment-end ""))
    (add-hook 'c-mode-hook 'sm-do-line-comments)

> Is that possible?

Hey, what sort of a question is that?  This is Emacs.  :-)

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Add functions to C-mode?

[Eli Zaretskii]

> From: David Hansen <david.hansen@gmx.net>
> Date: Sun, 20 Apr 2008 09:17:15 +0200
> 
> On Sat, 19 Apr 2008 14:08:18 -0700 (PDT) Jason Rumney wrote:
> 
> > On Apr 19, 6:16 pm, David Hansen <david.han...@gmx.net> wrote:
> >
> >> If you insist on "//" (which is btw not ANSI C)
> >
> > Single line comments starting with // are part of the current ANSI and
> > ISO standard (C99)
> > .
> 
> AFAIK a standard w/o implementation.

??? You mean GCC does not count?  The below compiles without any
warnings with GCC 3.4.2:

$ cat tcomment.c
int main (void)
{
  int foo = 3; // C99 comment

  return foo;
}

$ gcc -std=c99 -Wall -Wextra -pedantic tcomment.c
$

Re: Add functions to C-mode?

[David Hansen]

On Sun, 20 Apr 2008 15:26:08 +0300 Eli Zaretskii wrote:

>> From: David Hansen <david.hansen@gmx.net>
>> Date: Sun, 20 Apr 2008 09:17:15 +0200
>> 
>> On Sat, 19 Apr 2008 14:08:18 -0700 (PDT) Jason Rumney wrote:
>> 
>> > On Apr 19, 6:16 pm, David Hansen <david.han...@gmx.net> wrote:
>> >
>> >> If you insist on "//" (which is btw not ANSI C)
>> >
>> > Single line comments starting with // are part of the current ANSI and
>> > ISO standard (C99)
>> > .
>> 
>> AFAIK a standard w/o implementation.
>
> ??? You mean GCC does not count?  The below compiles without any
> warnings with GCC 3.4.2:
>
> $ cat tcomment.c
> int main (void)
> {
>   int foo = 3; // C99 comment
>
>   return foo;
> }
>
> $ gcc -std=c99 -Wall -Wextra -pedantic tcomment.c
> $

Supporting one tiny feature doesn't make it a full implementation of
C99.

David

Re: Add functions to C-mode?

[Richard G Riley]

David Hansen <david.hansen@gmx.net> writes:

> On Sun, 20 Apr 2008 15:26:08 +0300 Eli Zaretskii wrote:
>
>>> From: David Hansen <david.hansen@gmx.net>
>>> Date: Sun, 20 Apr 2008 09:17:15 +0200
>>> 
>>> On Sat, 19 Apr 2008 14:08:18 -0700 (PDT) Jason Rumney wrote:
>>> 
>>> > On Apr 19, 6:16 pm, David Hansen <david.han...@gmx.net> wrote:
>>> >
>>> >> If you insist on "//" (which is btw not ANSI C)
>>> >
>>> > Single line comments starting with // are part of the current ANSI and
>>> > ISO standard (C99)
>>> > .
>>> 
>>> AFAIK a standard w/o implementation.
>>
>> ??? You mean GCC does not count?  The below compiles without any
>> warnings with GCC 3.4.2:
>>
>> $ cat tcomment.c
>> int main (void)
>> {
>>   int foo = 3; // C99 comment
>>
>>   return foo;
>> }
>>
>> $ gcc -std=c99 -Wall -Wextra -pedantic tcomment.c
>> $
>
> Supporting one tiny feature doesn't make it a full implementation of
> C99.
>
> David

http://gcc.gnu.org/c99status.html

It's far from "one tiny feature".

Re: Add functions to C-mode?

[Eli Zaretskii]

> From: David Hansen <david.hansen@gmx.net>
> Date: Sun, 20 Apr 2008 14:42:20 +0200
> 
> On Sun, 20 Apr 2008 15:26:08 +0300 Eli Zaretskii wrote:
> 
> >> From: David Hansen <david.hansen@gmx.net>
> >> Date: Sun, 20 Apr 2008 09:17:15 +0200
> >> 
> >> On Sat, 19 Apr 2008 14:08:18 -0700 (PDT) Jason Rumney wrote:
> >> 
> >> > On Apr 19, 6:16 pm, David Hansen <david.han...@gmx.net> wrote:
> >> >
> >> >> If you insist on "//" (which is btw not ANSI C)
> >> >
> >> > Single line comments starting with // are part of the current ANSI and
> >> > ISO standard (C99)
> >> > .
> >> 
> >> AFAIK a standard w/o implementation.
> >
> > ??? You mean GCC does not count?  The below compiles without any
> > warnings with GCC 3.4.2:
> >
> > $ cat tcomment.c
> > int main (void)
> > {
> >   int foo = 3; // C99 comment
> >
> >   return foo;
> > }
> >
> > $ gcc -std=c99 -Wall -Wextra -pedantic tcomment.c
> > $
> 
> Supporting one tiny feature doesn't make it a full implementation of
> C99.

But this discussion _was_ about that one feature.

Re: Add functions to C-mode?

[saneman]

Alan Mackenzie wrote:
> Hi, Saneman!
> 
> On Sat, Apr 19, 2008 at 01:04:06PM +0200, saneman wrote:
>> I would like to add/change the comment/uncomment function in the C-mode 
>> for emacs.
> 
>> Currently it only works when a piece of text is selected and then /* */
>> is inserted.
> 
> OK, just to check, "it" here means "M-;" (or your newly bound C-d), bound
> to `comment-dwim', doesn't it?
> 
> I'm not sure about "selected" (I don't use delete-selection-mode and
> stuff like that), but the "/* */" style of comments is fixed for C.
> Somebody asked some while ago for a way to change this to "//", and I'm
> planning to add a command to CC Mode (probably C-c C-;) in the next
> release to toggle the commenting style.
> 
>> I would like to change the function to just insert // even though some 
>> text might not be selected.
> 
> In the meantime, you could use the following workaround.  M-; (or your
> C-d ;-) will then insert "// ".
> 
>     (defun sm-do-line-comments ()
>       (setq comment-start "// ")
>       (setq comment-end ""))
>     (add-hook 'c-mode-hook 'sm-do-line-comments)
> 


But I still have to select the lines that I want to comment out. If the 
cursor is on a line the I would like to comment out and I press C-d the 
// get inserted and the end of the line.

Only when I select the line and then press C-d it works.

Is there some way to insert // at the start of the line without first 
selecting it?

Re: Add functions to C-mode?

[Alan Mackenzie]

Morning, Saneman

On Mon, Apr 21, 2008 at 09:36:55AM +0200, saneman wrote:
> Alan Mackenzie wrote:

> >On Sat, Apr 19, 2008 at 01:04:06PM +0200, saneman wrote:
> >>I would like to add/change the comment/uncomment function in the
> >>C-mode for emacs.

> >>Currently it only works when a piece of text is selected and then /* */
> >>is inserted.

[ .... ]

> But I still have to select the lines that I want to comment out. If the
> cursor is on a line the I would like to comment out and I press C-d the
> // get inserted and the end of the line.

> Only when I select the line and then press C-d it works.

> Is there some way to insert // at the start of the line without first 
> selecting it?

I'm not quite sure exactly what you mean, but I don't think so (other
than typing the two "/"s yourself, but that's boring).

What exactly do you mean by "selecting" and why do you want to avoid
this?  Somehow or other, you've got to indicate to Emacs _which_ lines(s)
you want commented out (even if it's only one line).

"Selecting" isn't really Emacs jargon.  When you drag the mouse over a
buffer, the "mark" is left where you started, and point is put where you
finish.  The "region" is the bit between point and mark, and many
commands operate on the region.  There are lots of ways of setting the
mark, too.  C-<space> is the most basic.

So, if you want to comment out lines (like all good programming standards
forbid, yet everybody does ;-), make the region the pertinent lines.
Then do C-c C-c (`comment-region').  If you later want to undo this, put
the region round these lines again, then do C-u C-c C-c.

Again, you have to "select" the lines, so I'm not quite sure exactly what
you want.  But the above might be good enough.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Add functions to C-mode?

[Richard G Riley]

Alan Mackenzie <acm@muc.de> writes:

> Morning, Saneman
>
> On Mon, Apr 21, 2008 at 09:36:55AM +0200, saneman wrote:
>> Alan Mackenzie wrote:
>
>> >On Sat, Apr 19, 2008 at 01:04:06PM +0200, saneman wrote:
>> >>I would like to add/change the comment/uncomment function in the
>> >>C-mode for emacs.
>
>> >>Currently it only works when a piece of text is selected and then /* */
>> >>is inserted.
>
> [ .... ]
>
>> But I still have to select the lines that I want to comment out. If the
>> cursor is on a line the I would like to comment out and I press C-d the
>> // get inserted and the end of the line.
>
>> Only when I select the line and then press C-d it works.
>
>> Is there some way to insert // at the start of the line without first 
>> selecting it?
>
> I'm not quite sure exactly what you mean, but I don't think so (other
> than typing the two "/"s yourself, but that's boring).
>
> What exactly do you mean by "selecting" and why do you want to avoid

I would assume he means selecting the text. As one does for cut and
paste. Standard region manipulation.

> this?  Somehow or other, you've got to indicate to Emacs _which_ lines(s)
> you want commented out (even if it's only one line).
>
> "Selecting" isn't really Emacs jargon.  When you drag the mouse over a

Neither is "dragging a mouse" :-;

> buffer, the "mark" is left where you started, and point is put where you
> finish.  The "region" is the bit between point and mark, and many
> commands operate on the region.  There are lots of ways of setting the
> mark, too.  C-<space> is the most basic.

I think it would be fair to say that "selecting the text" is perfectly
clear in this instance.

>
> So, if you want to comment out lines (like all good programming standards
> forbid, yet everybody does ;-), make the region the pertinent lines.

I must admit to never having heard of this - commenting out is a very
common thing to do during development.

> Then do C-c C-c (`comment-region').  If you later want to undo this, put
> the region round these lines again, then do C-u C-c C-c.

In my set up the command is comment-dwim accessed from "M-;". I guess
this is part of emacs-22?

Re: Add functions to C-mode?

[Alan Mackenzie]

Evening, Richard!

On Mon, Apr 21, 2008 at 01:49:57PM +0200, Richard G Riley wrote:

> Alan Mackenzie <acm@muc.de> writes:

> > Morning, Saneman

> > On Mon, Apr 21, 2008 at 09:36:55AM +0200, saneman wrote:
> >> Alan Mackenzie wrote:

> >> >>Currently it only works when a piece of text is selected and then
> >> >>/* */ is inserted.

> > [ .... ]

> >> But I still have to select the lines that I want to comment out. If
> >> the cursor is on a line the I would like to comment out and I press
> >> C-d the // get inserted and the end of the line.

> >> Only when I select the line and then press C-d it works.

> >> Is there some way to insert // at the start of the line without
> >> first selecting it?

> > I'm not quite sure exactly what you mean, but I don't think so (other
> > than typing the two "/"s yourself, but that's boring).

> > What exactly do you mean by "selecting" and why do you want to avoid
> > this?

> I would assume he means selecting the text. As one does for cut and
> paste. Standard region manipulation.

No.  "Selection" means chosing something from a range of alternatives.
What is often called "selection" in editors other than emacs is actually
nothing of the kind.  It's usually something more like "highlighting" or
"marking".

The point of my question was to find out why Saneman objects to this
"selecting", so as to be able to suggest something better.

> > Somehow or other, you've got to indicate to Emacs _which_ lines(s)
> > you want commented out (even if it's only one line).

> > "Selecting" isn't really Emacs jargon.  When you drag the mouse over
> > a buffer, the "mark" is left where you started, and point is put
> > where you finish.  The "region" is the bit between point and mark,
> > and many commands operate on the region.  There are lots of ways of
> > setting the mark, too.  C-<space> is the most basic.

> I think it would be fair to say that "selecting the text" is perfectly
> clear in this instance.

Except that it's not Emacs terminology.  Also, although it's a nice
difference, the region in Emacs is a portion of the buffer, not merely
the text within it; it's the blackboard as well as the chalk.  So talking
about selecting "the text" can be confusing.

> > So, if you want to comment out lines (like all good programming
> > standards forbid, yet everybody does ;-), make the region the
> > pertinent lines.  Then do C-c C-c (`comment-region').  If you later
> > want to undo this, put the region round these lines again, then do
> > C-u C-c C-c.

> In my set up the command is comment-dwim accessed from "M-;". I guess
> this is part of emacs-22?

No, that's a different command.  M-; (usually) adds a comment at the end
of the current line, C-c C-c comments out the code in the region.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Add functions to C-mode?

[Richard G Riley]

Alan Mackenzie <acm@muc.de> writes:

> Evening, Richard!
>
> On Mon, Apr 21, 2008 at 01:49:57PM +0200, Richard G Riley wrote:
>
>> Alan Mackenzie <acm@muc.de> writes:
>
>> > Morning, Saneman
>
>> > On Mon, Apr 21, 2008 at 09:36:55AM +0200, saneman wrote:
>> >> Alan Mackenzie wrote:
>
>> >> >>Currently it only works when a piece of text is selected and then
>> >> >>/* */ is inserted.
>
>> > [ .... ]
>
>> >> But I still have to select the lines that I want to comment out. If
>> >> the cursor is on a line the I would like to comment out and I press
>> >> C-d the // get inserted and the end of the line.
>
>> >> Only when I select the line and then press C-d it works.
>
>> >> Is there some way to insert // at the start of the line without
>> >> first selecting it?
>
>> > I'm not quite sure exactly what you mean, but I don't think so (other
>> > than typing the two "/"s yourself, but that's boring).
>
>> > What exactly do you mean by "selecting" and why do you want to avoid
>> > this?
>
>> I would assume he means selecting the text. As one does for cut and
>> paste. Standard region manipulation.
>
> No.  "Selection" means chosing something from a range of alternatives.
> What is often called "selection" in editors other than emacs is actually
> nothing of the kind.  It's usually something more like "highlighting" or
> "marking".

I think my point was that in the context "selection" was fairly
obvious. Possibly I am wrong.

>
> The point of my question was to find out why Saneman objects to this
> "selecting", so as to be able to suggest something better.
>
>> > Somehow or other, you've got to indicate to Emacs _which_ lines(s)
>> > you want commented out (even if it's only one line).
>
>> > "Selecting" isn't really Emacs jargon.  When you drag the mouse over
>> > a buffer, the "mark" is left where you started, and point is put
>> > where you finish.  The "region" is the bit between point and mark,
>> > and many commands operate on the region.  There are lots of ways of
>> > setting the mark, too.  C-<space> is the most basic.
>
>> I think it would be fair to say that "selecting the text" is perfectly
>> clear in this instance.
>
> Except that it's not Emacs terminology.  Also, although it's a nice

Possibly not. But people who come to a help group are often not fluent
in "emacs" or "whatever" speak. I was merely pointing out that in the
context it seemed (to me) fairly clear what he meant.

> difference, the region in Emacs is a portion of the buffer, not merely
> the text within it; it's the blackboard as well as the chalk.  So talking
> about selecting "the text" can be confusing.

Yes - I can kind of accept that if one were to over think it.

>
>> > So, if you want to comment out lines (like all good programming
>> > standards forbid, yet everybody does ;-), make the region the
>> > pertinent lines.  Then do C-c C-c (`comment-region').  If you later
>> > want to undo this, put the region round these lines again, then do
>> > C-u C-c C-c.
>
>> In my set up the command is comment-dwim accessed from "M-;". I guess
>> this is part of emacs-22?
>
> No, that's a different command.  M-; (usually) adds a comment at the end
> of the current line, C-c C-c comments out the code in the region.

Not on my set up. It "does what I want" .. but that could be because of
changes I have long forgotten - a common issue with rusty .emacs  :-;

In other words, if I select some text ( to be devils advocate with the
terminology in this instance) it comments out the selected region ..

Re: Add functions to C-mode?

[David Hansen]

On Sun, 20 Apr 2008 16:51:43 +0300 Eli Zaretskii wrote:

>> [C vs C++ comments]
>
> But this discussion _was_ about that one feature.

For me it was about, that there is no benefit in changing c-modes
comment style but only potential drawbacks.

David

Re: Add functions to C-mode?

[David Hansen]

On Sun, 20 Apr 2008 15:28:46 +0200 Richard G. Riley wrote:

> David Hansen <david.hansen@gmx.net> writes:
>
>> Supporting one tiny feature doesn't make it a full implementation of
>> C99.
>>
>> David
>
> http://gcc.gnu.org/c99status.html
>
> It's far from "one tiny feature".

Still there is AFAIK no C99 implementation, and I think GCC is far
leading here.  If you want to write portable code it's better to not use
C99 features or at least limit yourself as much as feasible.

David