set_window_buffer

set_window_buffer

[Richard M. Stallman]

    +2008-09-12  Stefan Monnier  <monnier@iro.umontreal.ca>
    +
    +	* window.c (set_window_buffer): Always preserve current-buffer.
    +

That may be a good change, but I suspect it leads to changes in Lisp
primitives that ought to be documented in NEWS and in the Lisp Manual.

Re: set_window_buffer

[Stefan Monnier]

>     +2008-09-12  Stefan Monnier  <monnier@iro.umontreal.ca>
>     +
>     +	* window.c (set_window_buffer): Always preserve current-buffer.

> That may be a good change, but I suspect it leads to changes in Lisp
> primitives that ought to be documented in NEWS and in the Lisp Manual.

While nowhere does it say that the buffer is preserved, I couldn't find
any place where set-window-buffer is said to sometimes change
current-buffer (not even a vague hint).  I think this is a pure bug fix.


        Stefan

Re: set_window_buffer

[martin rudalics]

 >> That may be a good change, but I suspect it leads to changes in Lisp
 >> primitives that ought to be documented in NEWS and in the Lisp Manual.
 >
 > While nowhere does it say that the buffer is preserved, I couldn't find
 > any place where set-window-buffer is said to sometimes change
 > current-buffer (not even a vague hint).  I think this is a pure bug fix.

IMHO we should mention it in NEWS.  I suppose a couple of applications
not distributed with Emacs might rely on the faulty behavior.

martin

Re: set_window_buffer

[Stefan Monnier]

>>> That may be a good change, but I suspect it leads to changes in Lisp
>>> primitives that ought to be documented in NEWS and in the Lisp Manual.
>> 
>> While nowhere does it say that the buffer is preserved, I couldn't find
>> any place where set-window-buffer is said to sometimes change
>> current-buffer (not even a vague hint).  I think this is a pure bug fix.

> IMHO we should mention it in NEWS.  I suppose a couple of applications
> not distributed with Emacs might rely on the faulty behavior.

I'd be really impressed if that's the case.


        Stefan

Re: set_window_buffer

[martin rudalics]

 >> IMHO we should mention it in NEWS.  I suppose a couple of applications
 >> not distributed with Emacs might rely on the faulty behavior.
 >
 > I'd be really impressed if that's the case.

I probably can't impress you but in one routine I originally wrote for
Emacs 21 I found

;;; (defsubst set-window-buffer-only (window buffer &optional keep-margins)
;;;   "As `set-window-buffer' but don't change current buffer."
;;;   (let ((current-buffer (current-buffer)))
;;;     (set-window-buffer window buffer keep-margins)
;;;     (set-buffer current-buffer)))

so this already was a problem for me.  Later I apparently changed my
mind, used `set-window-buffer' instead, and had to fix this today again.
I recall a similar problem with `save-selected-window' which in certain
cases refused to restore the current buffer.

martin