Re: How to read an integer from the minibuffer

[Gregory Heytings]

> Rather, I meant show how to use the second solution to solve
> the OPs example, i.e. to read an integer and only an integer.

Just use

(restricted-read-from-minibuffer "Integer? " "^[0-9][0-9]*$")

instead of

(restricted-read-from-minibuffer "Integer? " "^[0-9][0-9]*$" "0123456789")

> I get if: Wrong number of arguments: string-match, 4

The fourth argument is new in Emacs 29, indeed.

> > (BTW, it seems that there's no way in Elisp to "expand" a regexp 
> > charset, e.g. "[0-9]" into "0123456789".  That would make the 
> > ALLOWED-CHARS argument easier to type in.)
>
> There is such a package, xr - the reverse of rx, LOL :)
>
>  https://elpa.gnu.org/packages/xr.html

Apparently it doesn't do what I want here, namely converting "[0-9]" into 
"0123456789", "[0-9a-f]" into "0123456789abcdef", and so forth.