intercepting undefined function errors

[Dan Aronson <Dan@Think.COM>]

    Date: Wed, 5 Aug 87 12:34 EDT
    From: Jeffrey P. Golden <jpg@allegheny.scrc.symbolics.com>

    We are running Beta Version 2.00 on the Apollo.

    As you may know, MACSYMA has long had an "autoload" feature 
    whereby an "undefined function" may have an AUTOLOAD property 
    which indicates a file which contains the function's definition. 
    The file is loaded when a call to the undefined function is 
    attempted.  (This scheme was very useful in the days of limited 
    address space.  It is still used to autoload a few "share" files.)

    To make it work under Lucid, we need a way to intercept 
    undefined function errors.  (It would be interesting if Lucid had 
    an autoload capability as did Maclisp, but I'm not expecting that.)
    We are willing to intercept all errors if need be as long as we can 
    detect which error we've got, handle those we can, and decline to 
    handle the others. 

    I cannot find the capability I need in the Lucid documentation. 
    Can someone tell me if there is a way to do what I want in Lucid?

    Also, is there a mailing list for asking questions like this 
    directly of Lucid Inc.?



I have just written a handler for functions that are typed into the
wrong package (ie typeing (FOO) when you actually mean (SYSTEM::FOO))
that queries the user if FOO doesn't exist to ask if you actually meant
SYSTEM::FOO).  I did this by redefining SYMBOL-FUNCTION.  If you want
this code as an example let me know.

--Dan