Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!deimos!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!m.cs.uiuc.edu!reingold
From: reingold@m.cs.uiuc.edu
Newsgroups: comp.emacs
Subject: Re: Need read-number function
Message-ID: <4300070@m.cs.uiuc.edu>
Date: 9 Feb 90 17:37:46 GMT
References: <4300068@m.cs.uiuc.edu>
Lines: 21
Nf-ID: #R:m.cs.uiuc.edu:4300068:m.cs.uiuc.edu:4300070:000:820
Nf-From: m.cs.uiuc.edu!reingold    Feb  8 19:19:00 1990


Here's the way I've written the general form.  Now that I've got it, I
can't figure out how I managed without it!

(defun read-object (prompt acceptable &optional initial-contents)
  "Return an object read from the minibuffer.
Prompt with the string PROMPT and use the function ACCEPTABLE to decide if
entered item is acceptable.  If non-nil, optional third arg INITIAL-CONTENTS
is a string to insert in the minibuffer before reading."
  (let ((value (read-minibuffer prompt initial-contents)))
    (while (not (funcall acceptable value))
      (setq value (read-minibuffer prompt initial-contents)))
    value))


For example, to read a month, defaulting to current-month, use

    (read-object
      "Enter month (1-12): "
      '(lambda (x) (and (integerp x) (<= 1 x) (<= x 12)))
      (int-to-string current-month))