Re: (interactive "r") and (use-region-p)

[Ingo Lohmar]

On Thu, Mar 16 2017 13:20 (-0400), Sam Steingold wrote:
> --8<---------------cut here---------------start------------->8---
> (defun my-command (beg end)
>   (interactive "r")
>   (if (use-region-p)
>       (my-command-region beg end)
>     (my-command-non-region)))
> --8<---------------cut here---------------end--------------->8---

Hi Sam,

AFAIK, you cannot use the (interactive "r") form for this "dwim-ish"
kind of behavior.  I find it easiest to just omit the arguments and the
interactive form, and then use (region-beginning) and (region-end) in
the function body.

If you want to be able to use the function non-interactively as well,
you could make the arguments optional and check for (or (beg
(use-region-p))).

HTH.