setf buffer-file-name

setf buffer-file-name

[Devon Sean McCullough]

Hi Dave,

Two questions and two patches.


(A) Should cl-macs.el patches go to you or
to <Emacs-Devel@gnu.org> or someplace like that?

(B) Should (with-current-buffer nil ...)
keep the same buffer current rather than error?
This would fix a bug in (setf (buffer-modified-p) x)
left broken below in case this makes it moot.


(1) Documented defsetf simple form third argument.

(2) Broken (setf (buffer-file-name buffer) filename)
fixed below.  Perhaps the optional buffer arg
came after the old defsetf was written.
Will fix more in this same vein
as time permits.


		Peace
			--Devon
	 /~\
	 \ /	Health Care
	  X 	not warfare
	 / \

	Dubya slime won the digital vote
	Kerry slime won the popular vote

PS: Thanks for the software!

Index: lisp/emacs-lisp/cl-macs.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/emacs-lisp/cl-macs.el,v
retrieving revision 1.72
diff -u -r1.72 cl-macs.el
--- lisp/emacs-lisp/cl-macs.el	3 Apr 2008 13:42:25 -0000	1.72
+++ lisp/emacs-lisp/cl-macs.el	7 Apr 2008 04:56:12 -0000
@@ -1604,9 +1604,13 @@
 This macro is an easy-to-use substitute for `define-setf-method' that works
 well for simple place forms.  In the simple `defsetf' form, `setf's of
 the form (setf (NAME ARGS...) VAL) are transformed to function or macro
-calls of the form (FUNC ARGS... VAL).  Example:
+calls of the form (FUNC ARGS... VAL).  Examples:
 
   (defsetf aref aset)
+  (defsetf file-modes set-file-modes t)
+
+Optional third arg omitted or nil assumes FUNC always returns VAL,
+non-nil wraps it in a (progn ... VAL) in case it might not.
 
 Alternate form: (defsetf NAME ARGLIST (STORE) BODY...).
 Here, the above `setf' call is expanded by binding the argument forms ARGS
@@ -1717,7 +1721,13 @@
 (defsetf rest setcdr)
 
 ;;; Some more Emacs-related place types.
-(defsetf buffer-file-name set-visited-file-name t)
+(defsetf buffer-file-name (&optional buf) (filename)
+  (list 'progn 
+	(list 'if buf
+	      (list 'with-current-buffer buf
+		    (list 'set-visited-file-name filename))
+	      (list 'set-visited-file-name filename))
+	filename))
 (defsetf buffer-modified-p (&optional buf) (flag)
   (list 'with-current-buffer buf
 	(list 'set-buffer-modified-p flag)))

Re: setf buffer-file-name

[Stefan Monnier]

> (A) Should cl-macs.el patches go to you or
> to <Emacs-Devel@gnu.org> or someplace like that?

You can report any bug in the code of Emacs with M-x report-emacs-bug.
I do not know if Dave still worries about CL, but indeed if he does not
we should fix the cl*.el headers to say "Maintainer: FSF".

> (B) Should (with-current-buffer nil ...)
> keep the same buffer current rather than error?

I don't see a strong need to make it work as you suggest.
It's pretty easy to use (or <foo> (current-buffer)) for the few cases
where this might be useful.

> (1) Documented defsetf simple form third argument.

Thanks.

>  ;;; Some more Emacs-related place types.
> -(defsetf buffer-file-name set-visited-file-name t)
> +(defsetf buffer-file-name (&optional buf) (filename)
> +  (list 'progn 
> +	(list 'if buf
> +	      (list 'with-current-buffer buf
> +		    (list 'set-visited-file-name filename))
> +	      (list 'set-visited-file-name filename))
> +	filename))

Actually, while your patch is correct, I wonder if using
set-visited-file-name is really a good idea here.  Yes, it's probably
the cleanest way to set buffer-file-name in some cases, but it does
a lot more than just set buffer-file-name, so I'm not sure if it should
be hidden as a mere "setf".
I.e., I suggest to remove this defsetf altogether.


        Stefan