Inserting buttons into Emacs buffers

This is something I discovered during development of beeminder.el version 1.2. I wanted to have some text in the buffer saying “View all data” that would perform an action when clicked or when the user pressed RET on it.

I tried a couple of approaches, such as setting text properties in the buffer and then searching at the current point when RET was pressed. But those solutions didn’t feel right.

Finally, I discovered the insert-button function which does what I wanted.

The previous code looked a little like this:

(insert "View all data")
(put-text-property (line-beginning-position)
                   (line-end-position)
                   'beeminder-is-read-more
                   t)

(defun beeminder-handle-view-all-data-link ()
  "Handle a click on the 'Read more data' text."
  (when (get-text-property (point) 'beeminder-is-read-more)
        (beeminder-view-data-for-current-goal)))

;; Bind to <RET>
(define-key beeminder-mode-map
            (kbd "<RET>")
            #'beeminder-handle-view-all-data-link)

It’s not the cleanest code ever, and it’s a lot of effort for a simple button. By using insert-button, it now looks like this:

(insert-button "View all data"
               'action (lambda (_arg) (beeminder-view-data-for-current-goal)))

Much better!