Turning On Undo in a Temporary Buffer

Today I learned something new from a short post on Xah Lee’s blog. The idea is that you’ve written a command that generates output in a temporary buffer and you want to enable the undo function for the buffer so that the user can edit the buffer with undo capabilities.

You can’t link to individual posts on Lee’s blog but you can search for the date of the post, which is 2014-05-30. Here’s the code from that post in case you have trouble finding the post:

(with-output-to-temp-buffer outputBuffer
  ;; …
  (switch-to-buffer outputBuffer)
  (setq buffer-undo-list nil )          ; enable undo
  )

As you can see, it’s merely a matter of providing an empty buffer-undo-list for the buffer. This isn’t the sort of thing you’re going to need very often and it would probably be pretty hard to find it in the documentation¹. So this post is mainly a note to myself although I hope it might help others who didn’t know this fact.