Re: [elisp]How to ask and provide a Default value?

[Joakim Hove <hove@bccs.no>]

Hello,

maybe you can use this little function:

(defun read-number-with-default (prompt &optional default)
  (let ((default-string (if default (number-to-string default) "")))
    (string-to-number (read-from-minibuffer prompt default-string))))

Observe two things:

 1. The default value is presented to the read routine as
    "INITIAL-CONTENTS", and *not* "DEFAULT-VALUE".

 2. The routine does not check the number format, and
    (string-to-number ) seemingly eats anything with digits in it.

In case you want to use this function you would typically read the
input in the body of the function, i.e. something like:

(defun sleeve-step-region (beginning end base step column)
  "Insert a column of increasing numbers in the region."
  (let* ((beginning (read-number-with-default "Beginning: " 100))
         (end       (read-number-with-default "End: " (+ beginning 10)))

...

HTH - Joakim



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