Move to beginning of line when top arrow is pressed in beg-of-buffer line

Question

Like in all modern editors, including the SE Q&A fields, I'd like my cursor to move to the beginning of the first line, when I press the Up arrow on the first line of a buffer. Currently, it stays in the middle of the line and messages "Beginning of buffer".

How can I get that behavior ?

(Bonus points for the same thing with Down arrow at end of buffer.)

Answer 1

You can do such thing by adding advice around previous-line and next-line, motion commands that are bound to these keys by default.

Here's the code:

(advice-add #'previous-line :around
            (lambda (func &rest args)
              (condition-case nil
                  (apply func args)
                (beginning-of-buffer (beginning-of-line)))))

(advice-add #'next-line :around
            (lambda (func &rest args)
              (condition-case nil
                  (apply func args)
                (end-of-buffer (end-of-line)))))

Add it to your init file to make it persistent.

There might be some variable to tweak these functions to work the way you'd want them to, but I couldn't find it with a couple of searches.