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Who Called My Function?

Someone asked why his Emacs starts up with two split screen. Apparently something in his init.el caused that.

But how can we find what caused the problem? I searched around and found a way to check "backtrace frame" in Emacs: backtrace-frames.

Here is what I cooked up:

(advice-add 'split-window-right :before (lambda (&rest _) (print (backtrace-frames))))
(defun some-function () (split-window-right))

So when I call the function some-funtion, a split window is created with following information printed:

((t backtrace-frames nil nil)
 (nil print
      ((backtrace-frames))
      nil)
 (t
  (lambda
    (&rest _)
    (print
     (backtrace-frames)))
  nil nil)
 (t apply
    ((lambda
       (&rest _)
       (print
        (backtrace-frames)))
     nil)
    nil)
 (t split-window-right nil nil)
 (t some-function nil nil)
 (t eval
    ((some-function)
     nil)
    nil)
 (t elisp--eval-last-sexp
    (t)
    nil)
 (t eval-last-sexp
    (t)
    nil)
 (t eval-print-last-sexp
    (nil)
    nil)
 (t funcall-interactively
    (eval-print-last-sexp nil)
    nil)
 (t call-interactively
    (eval-print-last-sexp nil nil)
    nil)
 (t command-execute
    (eval-print-last-sexp)
    nil))

We can see some-funtion is right before split-window. Cool. As for the other t and nil stuff, I chose to not bother.

Written by Yuan Fu <casouri@gmail.com>

First Published on 2018-10-14 Sun 00:00

Last modified on 2018-11-11 Sun 19:23