Is there an easy way to use thing-at-point to initialize interactive read string (interactive "sfoo:")

Question

Is there an easy way to use thing-at-point to initialize the contents of an interactive string reading?

I have a function the looks something like this:

(defun foo (string)
   (interactive "sString:")
   ;; does something with string
   )

But I'd really like it if when I did M-x foo, that it filled the minibuffer with the thing-at-point. In this case (thing-at-point 'word).

Is the only way to get that to use an explicit list argument to interactive, something like:

(defun foo (string)
   (interactive (list (read-from-minibuffer 
                        "String:" ;; prompt
                        (thing-at-point 'word) ;; initial value
                       ) ) ) ; interactive
   ;; does something with string
   )

And if I do so, do my own history list etc?

Answer 1

Yes, use interactive with a Lisp sexp, not a literal string. You can't specify particular defaulting with a literal string arg.

You can use read-from-minibuffer, read-string, or completing-read.

Provide the value returned by (thing-at-point 'word) as the DEFAULT-VALUE argument to one of those functions, not the INITIAL-CONTENTS argument.

(You can use the initial-contents/input arg if you like, but Emacs convention prefers that you use the default-value arg nowadays.)

As for the input history list: you can provide your own history variable, or you can just use the default history list, minibuffer-history. If you use your own then the only entries on it will be previous inputs to minibuffer-input reads that use your own history variable. That can mean less noise interactively, but it can also be handy to not be so specific. It's up to you.