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Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!alberta!ncc!et!steve
From: steve@et.UUCP
Newsgroups: comp.emacs
Subject: &optional keywords in function parameters
Message-ID: <197@et.UUCP>
Date: Wed, 17-Jun-87 12:28:58 EDT
Article-I.D.: et.197
Posted: Wed Jun 17 12:28:58 1987
Date-Received: Fri, 19-Jun-87 05:09:18 EDT
Distribution: na
Organization: ETCOM International, Edmonton Alberta, Canada
Lines: 26
Keywords: &optional


   Does anyone have a good definition of exactly what the &optional
keyword does in the function parameter definitions.   I have the
general idea and I wish to use it for some of my functions, but I
don't know some things like:

  1.  What values do the optional parameters acquire if they are not
  passed by the calling routine?

  2.  Is there some way to specify a default value if they are not
  passed by the calling routine?

* Most Important *
  3.  Is there a limit to the number of optional parameters and can a
  function have nothing but optional parameters.

   I can not wait until the programmer's manual becomes available.  It
will aid life in extension writing immeasurably.  Thanks in advance.


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