Question

I am trying to have a dynamic prompt from my elisp function. I want something like replace-regexp where it will show you the last regexp entered. I tried (interactive (concat ‘sab’ ‘bab’))) that doesnt work!

I also tried message like format (interactive ‘s %s’ last-used-regexp)

and that doesn’t work! Anyone know how to do this?

Thank you!

Answer 1

M-x find-function is your friend. It will tell you how anything in emacs works by showing you the source code. Using it, I find that query-regexp-replace calls query-replace-read-args which calls query-replace-read-from which calls read-from-minibuffer using a prompt created from the last used regexp, which is saved in the dotted pair query-replace-defaults.

So:

(defun my-func ()   'Do stuff...'   (interactive)   (read-from-minibuffer 'Regexp? ' (first query-replace-defaults))) 

is a command that throws up a prompt with the last entered regexp as the default.