<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=iso-8859-1"> <META content="MSHTML 6.00.6000.16414" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV>Module level variables can be assigned to only by the module itself. In this way the writer of a module is assured that the user of the module cannot corrupt the variables.</DIV> <DIV>Matthias Felleisen already suggested to use boxes in stead of variables:</DIV> <DIV> </DIV> <DIV>(module lang mzscheme<BR>  (provide f)<BR>  (define f (box 'who-cares?)))<BR> <BR>(module test mzscheme<BR>  (require lang)<BR>  (set-box! f 1)<BR>  (provide test1)<BR>  (define (test1) (unbox f)))<BR> <BR>(require test)<BR>(test1) ; --> 1</DIV> <DIV> </DIV> <DIV>Jos</DIV> <DIV> </DIV> <DIV><FONT face=Arial size=2>(((((lambda(x)((((((((x x)x)x)x)x)x)x)x))<BR>    (lambda(x)(lambda(y)(x(x y)))))<BR>   (lambda(x)(x)x))<BR>  (lambda()(printf "Greetings, Jos~n"))))</FONT></DIV> <BLOCKQUOTE style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B> <A title=support@taxupdate.com href="mailto:support@taxupdate.com">support@taxupdate.com</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A title=jos.koot@telefonica.net href="mailto:jos.koot@telefonica.net">jos koot</A> </DIV> <DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=plt-scheme@list.cs.brown.edu href="mailto:plt-scheme@list.cs.brown.edu">plt-scheme@list.cs.brown.edu</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, April 27, 2007 2:09 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [plt-scheme] namespace-variable-value</DIV> <DIV><BR></DIV><BR>On Fri, Apr 27, 2007 at 06:41:34PM +0200, jos koot wrote:<BR><BR>> (module lang mzscheme<BR>>   (printf "defining~n")<BR>>   (namespace-set-variable-value! 'f 1))<BR>> <BR>> (module test mzscheme<BR>>   (require lang) ; does the top level assignment (once only)<BR>>   (provide (all-defined))<BR>>   (define (test1) (namespace-variable-value 'f))) ; refers to the top level<BR>> <BR>> (require test) ;; prints defining<BR>> (test1)        ;; --> 1<BR>> (require lang) ;; does nothing<BR><BR>I'm hoping to set module-level variables, not top-level.  My understanding<BR>of the docs leads me to believe that namespace-variable-value can use<BR>mapping to return imported variable mappings.<BR><BR>Wayne<BR></BLOCKQUOTE></BODY></HTML>