Re: new buffer - should its mode reflect its name when the name matches auto-mode-alist?

[Kevin Rodgers]

Drew Adams wrote:
> > > Haven't thought about this before, but I wonder if the mode 
> > > should respect auto-mode-alist when you create a new buffer?
> > > There's no doubt a good reason or
> > > two why we don't do this - just wondering.
> > >
> > > E.g. `C-x b foo.el', where there is no existing buffer 
> > > foo.el. The mode is
> > > Fundamental; should it be Emacs-Lisp instead?
> > >
> > > (I realize that a new buffer need not be intended to be 
> > > saved as a file.)
> > As an end-user and not having contributed anything to Emacs myself, I
> > would expect the buffer to "respect" auto-mode-alist, i.e. set the
> > mode depending on the buffer name. However, I think the default
> > behavior when creating buffers non-interactively should *not* respect
> > auto-mode-alist.
>
> Yes, I meant interactively only, but should have made that clear. Thx.

I think I posted this in response to a request on gnu.emacs.help, back around 
2008-11-18, but I can't find it via Google:

(defadvice switch-to-buffer (around interactive-normal-mode activate)
  "When called interactively to create a new buffer not visiting a file,
temporarily bind `buffer-file-name' and call `normal-mode'."
  (let ((existing-buffer (get-buffer (ad-get-arg 0))))
    ad-do-it
    (when (and (interactive-p)
               (null existing-buffer)
               (null buffer-file-name))
      (let ((buffer-file-name (expand-file-name (buffer-name))))
        (normal-mode)))))

Not appropriate for src/buffer.c of course, but you get the idea.

--
Kevin Rodgers
Denver, Colorado, USA