<div class="gmail_quote">On Wed, Sep 15, 2010 at 14:57, Matthias Felleisen <<a href="mailto:matthias@ccs.neu.edu">matthias@ccs.neu.edu</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> Can we start from something simpler? The name of your macro suggests that you want something like this: (define one-and-only-one-instance (new (class my-super% ...))) This creates a class and creates a single instance. Because class is nested in the call to new, there is no way to get another instance. Would this be what you want? </blockquote><div> Okay, let me explain what I want to do (the name is not really set in stone yet). </div></div> There is a class a% defined somewhere, and an instance parameter current-a%-object of class a%. Suppose a% has methods foo and bar. Then I call: (class->singleton a% current-a%-object) This is supposed to define the forms (foo ....) and (bar ....) so that they act like (send (current-a%-object) foo ....), etc. I want to build these definitions automatically from the methods of the class. Anyway, beside the intended goal, I'd still like to know how solve the macro issue.