1 -*- mode: outline -*-

     2 

     3 * How debug?

     4 

     5 When your InitFile has a bug, or when you load external files that cause

     6 errors, the bug is often hard to find, because the Emacs Lisp reader does not

     7 know about line numbers and files – it just knows an error happened, and

     8 that’s it.

     9 

    10 You have several options:

    11 

    12   * Binary Search – select half of the file in a region, and M-x eval-region.

    13   Depending on whether that causes the error or not, split this half or the

    14   other half again, and repeat.

    15 

    16   * Simplified Binary Search – add (error “No error until here”) in the

    17   middle of your file. If you get the error “No error until here” when

    18   reloading the file, move the expression towards the back of the file,

    19   otherwise towards the front of the file.

    20 

    21   * Use a keyboard macro that moves forward one expression (sexp) and

    22   evaluates it.

    23 

    24   * Try the CommandLine? switch --debug-init.

    25 

    26   * Shouldn’t (setq debug-on-error t) help?