# HG changeset patch
# User Oleksandr Gavenko <gavenkoa@gmail.com>
# Date 1232377009 -7200
# Node ID e35491992b6202b47ba5cb48731fb22d318f51d6
# Parent  a0c29be69a91ff2a17fa4dc70d0209e8f41d8c94
up

diff -r a0c29be69a91 -r e35491992b62 emacs.rst
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/emacs.rst	Mon Jan 19 16:56:49 2009 +0200
@@ -0,0 +1,26 @@
+-*- mode: outline -*-
+
+* How debug?
+
+When your InitFile has a bug, or when you load external files that cause
+errors, the bug is often hard to find, because the Emacs Lisp reader does not
+know about line numbers and files – it just knows an error happened, and
+that’s it.
+
+You have several options:
+
+  * Binary Search – select half of the file in a region, and M-x eval-region.
+  Depending on whether that causes the error or not, split this half or the
+  other half again, and repeat.
+
+  * Simplified Binary Search – add (error “No error until here”) in the
+  middle of your file. If you get the error “No error until here” when
+  reloading the file, move the expression towards the back of the file,
+  otherwise towards the front of the file.
+
+  * Use a keyboard macro that moves forward one expression (sexp) and
+  evaluates it.
+
+  * Try the CommandLine? switch --debug-init.
+
+  * Shouldn’t (setq debug-on-error t) help?