Hi all - Just want to thank everyone (Jos, Matthew, Jens, and Eli) for providing the pointers - this is awesome help.  I will study the different methods and will definitely report back on my take aways ;) Very appreciated. Thanks, yinso <div>On 4/22/07, Eli Barzilay <<a href="mailto:eli@barzilay.org">eli@barzilay.org</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> On Apr 22, Matthew Flatt wrote: > At Sun, 22 Apr 2007 03:32:36 -0700, "Yin-So Chen" wrote: > > My motivation for having a conditional define is to make it play > > nice with the module system, which doesn't work well when having > > multiple definitions with the same name.  I was hoping there is an > > "automated" way of detecting whether a symbol is already defined > > in the current module, if so, either override or not import the > > definition. > > Within a module, `identifier-binding' should do the trick. Funny that this came right after the Swindle question -- they're related.  When you use `defmethod' Swindle is trying to guess whether you're defining a new method, or adding to an existing one.  See the code in "collects/swindle/clos.ss" (look for `identifier-binding') for how it's done -- my guess is that you'll want something similar. BUT -- having gone through that, I can tell you that you will need a lot of fighting to get things right.  It's a question whether it's worth it.  (In other words -- I often think that I should have not included a `defmethod' -- it's much cleaner to have only `defgeneric' and `add-method'.) --           ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:                   <a href="http://www.barzilay.org/"> http://www.barzilay.org/</a>                 Maze is Life! </blockquote></div> -- <a href="http://www.yinsochen.com">http://www.yinsochen.com</a> ...continuous learning...