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New macro with-demoted-errors
From: |
Stefan Monnier |
Subject: |
New macro with-demoted-errors |
Date: |
Sat, 07 Jul 2007 02:07:13 -0400 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.1.50 (gnu/linux) |
I often want to use CL's `ignore-errors' but am annoyed regularly that its
use tends to hide bugs and make them harder to track down.
So I sugest we introduce a new macro with-demoted-errors which does the same
thing except that errors are reported (via message) to the user rather than
being silently ignored. Also errors are not ignored if debug-on-error is
set, in the hope to make debugging easier.
The patch below includes a sample use of it in VC where it makes sure that
any error in a vc-BACKEND-registered function will not prevent the user from
visiting a file.
Stefan
--- orig/lisp/subr.el
+++ mod/lisp/subr.el
@@ -2552,6 +2552,20 @@
(or (input-pending-p)
,@body))))))
+(defmacro with-demoted-errors (&rest body)
+ "Run BODY and demote any errors to simple messages.
+If `debug-on-error' is non-nil, run BODY without catching its errors.
+This is to be used around code which is not expected to signal an error
+but which should be robust in the unexpected case that an error is signalled."
+ (declare (debug t) (indent 0))
+ (let ((err (make-symbol "err")))
+ `(lexical-let ((f (lambda () ,@body)))
+ (if debug-on-error
+ (funcall f)
+ (condition-case ,err
+ (funcall f)
+ (error (message "Error: %s" ,err) nil))))))
+
(defmacro combine-after-change-calls (&rest body)
"Execute BODY, but don't call the after-change functions till the end.
If BODY makes changes in the buffer, they are recorded
--- orig/lisp/vc-hooks.el
+++ mod/lisp/vc-hooks.el
@@ -834,7 +834,7 @@
(when buffer-file-name
(vc-file-clearprops buffer-file-name)
(cond
- ((vc-backend buffer-file-name)
+ ((with-demoted-errors (vc-backend buffer-file-name))
;; Look for pending-partial-checkin file and deal with it if found.
(vc-after-partial-checkin buffer-file-name)
;; Compute the state and put it in the modeline.
- New macro with-demoted-errors,
Stefan Monnier <=