Toggle breakpoint command from a gud source buffer

gud-toggle-bkpt.el

(defun my-gud-toggle-breakpoint ()
  "Enable/disable breakpoint at the current line of source buffer."
  (interactive)
  (save-excursion
    (beginning-of-line)
    (let* ((bol (point))
           (ovl (overlay-get (car (overlays-in bol bol)) 'before-string))
           (bptno (get-text-property 0 'gdb-bptno ovl))
           (bpten (get-text-property 0 'gdb-enabled ovl)))
      (if bpten (gud-basic-call (format "-break-disable %s" bptno))
        (gud-basic-call (format "-break-enable %s" bptno))))))
        
;; Use M-: (overlay-get (car (overlays-in (point) (point))) 'before-string)
;; to see the rest of the text properties addded by gud