-*- mode: outline -*-

* How debug ini file?

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.

** 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.

** Elisp.

 - Use a keyboard macro that moves forward one expression (sexp) and evaluates

   it.

 - Try C-x check-parens.

 - Set (setq debug-on-error t).

** CLI.

  $ emacs --no-init-file --no-site-file --debug-init

** 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.

* Using edebug.

The main entry point is ‘M-x edebug-defun’ (also on ‘C-u C-M-x’). Use it

instead of `C-x C-e’ or ‘C-M-x’ to evaluate a ‘defun’ and instrument it for

debugging.

You can disable edebug on a function by evaluating the function again using

‘C-M-x’.

* How debug func?

Use M-x debug-on-entry and M-x cancel-debug-on-entry to control

which functions will enter the debugger when called.

When next time that function called automatically loaded debug-mode.