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).