<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Mar 17, 2009, at 1:25 PM, Thomas Chust wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>2009/3/17 Jeff de Vries <<a href="mailto:jdevries@pfrog.com">jdevries@pfrog.com</a>>:<br><blockquote type="cite">I'm trying to create a macro that creates a set of global function<br></blockquote><blockquote type="cite">definitions where those functions share some common state.  Basically, the<br></blockquote><blockquote type="cite">intent is something like the following:<br></blockquote><blockquote type="cite">;;; doesn't work, creates local definitions instead of global ones<br></blockquote><blockquote type="cite">(let ((state (create-common-state)))<br></blockquote><blockquote type="cite">  (define (foo x) (use-common-state-one-way x state))<br></blockquote><blockquote type="cite">  (define (bar x) (use-common-state-another-way x state)))<br></blockquote><blockquote type="cite">[...]<br></blockquote><br>you could let your macro expand into a define-values form that looks like this:<br><br>  (define-values (foo bar)<br>    (let ([state (create-common-state)])<br>      (values<br>        (lambda (x) (use-common-state-one-way x state))<br>        (lambda (x) (use-common-state-another-way x state)))))<br></div></blockquote></div><br><div>Yes, that's what I was looking for.  Short, sweet, easy to understand, and does exactly what I wanted.</div><div><br></div><div>Regarding some of the other comments:</div><div><br></div><div>The original was "clunky" in the sense that it first created the global names (initially set to null), and then went back and set the values in another pass.  It was also not very clean if the create-common-state function blew up; in the original the global names are defined first, so if create-common-state blows up, those names are left hanging around.  The define-values approach gets around that issue, in that if create-common-state blows up, nothing gets defined.</div><div><br></div><div>The other suggestions basically create a global gensym'd name for the common-state.  But I really don't want these common-state objects polluting the global namespace, since they really don't need to.  Again, the define-values approach does what I want.</div><div><br></div><div>Thanks for all the comments and suggestions!</div><div>Jeff</div><div><br></div></body></html>