`insert' inside `with-current-buffer' deactivating the mark?

`insert' inside `with-current-buffer' deactivating the mark?

[Michael Heerdegen]

Hi,

if I eval the following in emacs -Q:

--8<---------------cut here---------------start------------->8---
(defun insert-in-some-other-buffer ()
  (with-current-buffer (get-buffer-create "*Test*")
    (insert ".")))

(add-hook 'post-command-hook 'insert-in-some-other-buffer)
--8<---------------cut here---------------end--------------->8---

the mark in any buffer is deactivated immediately after each command.
Looks like a bug to me - the use of `with-current-buffer' should prevent
influencing any other buffer than *Test*.  What am I missing?


Thanks,

Michael.

Re: `insert' inside `with-current-buffer' deactivating the mark?

[Christopher Schmidt]

Michael Heerdegen <michael_heerdegen@web.de> writes:
> if I eval the following in emacs -Q:
> (defun insert-in-some-other-buffer ()
>   (with-current-buffer (get-buffer-create "*Test*")
>     (insert ".")))
>
> (add-hook 'post-command-hook 'insert-in-some-other-buffer)
>
> the mark in any buffer is deactivated immediately after each command.
> Looks like a bug to me - the use of `with-current-buffer' should
> prevent influencing any other buffer than *Test*.  What am I missing?

    deactivate-mark

        Christopher

Re: `insert' inside `with-current-buffer' deactivating the mark?

[Michael Heerdegen]

Christopher Schmidt <christopher@ch.ristopher.com> writes:

> Michael Heerdegen <michael_heerdegen@web.de> writes:
> > if I eval the following in emacs -Q:
> > (defun insert-in-some-other-buffer ()
> >   (with-current-buffer (get-buffer-create "*Test*")
> >     (insert ".")))
> >
> > (add-hook 'post-command-hook 'insert-in-some-other-buffer)
> >
> > the mark in any buffer is deactivated immediately after each command.
> > Looks like a bug to me - the use of `with-current-buffer' should
> > prevent influencing any other buffer than *Test*.  What am I missing?
>
>     deactivate-mark

Thanks.  Yes, I know `deactivate-mark' - but why is it necessary here?
Why does changing another buffer deactivate the mark in the current
buffer?

Even if you activate the mark in one buffer, manually switch to another
buffer, edit it, and come back to the first buffer, the mark is still
active there.


Michael.

Re: `insert' inside `with-current-buffer' deactivating the mark?

[Stefan Monnier]

> Thanks.  Yes, I know `deactivate-mark' - but why is it necessary here?
> Why does changing another buffer deactivate the mark in the current
> buffer?

Because deactivate-mark is a global variable.  Note also that the mark is
not deactivated in some cases where it "should":

   M-: (progn (insert "a") (set-buffer (other-buffer))) RET

IOW the auto-deactivation is just a coarse heuristic, which only covers
most cases, but not all.


        Stefan