Re: C-x 2 and C-x 3

[Alan Mackenzie]

Hello, Drew.

On Thu, Oct 27, 2011 at 08:38:50AM -0700, Drew Adams wrote:
> > Copying is an implementation detail.

> No, it has nothing to do with implementation.  It is a user-level operation.
> Just like using `C' in Dired is a user-level copy operation.

> > The purpose of the command is to make a new window.

> Almost, but not quite.  The purpose of the command, what the command does, is 
> to
> make a new window...that is a copy of the selected window: same buffer.

> The command copies the selected window.  ...

That's a rather special use of the word "copy".  There is no copying,
just that you only see half of what you use to, but you see it twice - a
bit like some fancy mirror trick.  In fact, the second "copy" after C-x
2, is useless.  Only after scrolling does it make any sense.


> It does _not_ just make a new window.  It makes a new window with the
> same buffer (and same window-point value etc.).  And that's the point.

Not really.  The point is to make a new window.  Tell me, what buffer
are you going to display in this new window?  By default it's the same
buffer.  I suppose you could imagine displaying the _next_ buffer or
*scratch*, but the same buffer is as good as any.

A lot of the time, before the development of C-x 4 ..., you'd be
switching to a different buffer immediately anyway, just as even today
you might do C-x 2  C-x o  M-x man.

-- 
Alan Mackenzie (Nuremberg, Germany).