Thanks Will!  I tried it and it works ;) except the generic make method - i.e. can't do (make <my-struct> ...). After looking at the defstruct code - it appears that it calls a private function called struct-type->class* and this function builds on top of struct-type->class and use it to track the slots for all the types created via defstruct and thus allow the structs to be created via made.  I guess to fully integrate with the make method the function struct-type->class* should be exported...? Thanks! yc <div>On 9/6/07, Will M Farr <<a href="mailto:farr@mit.edu">farr@mit.edu</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 Sep 6, 2007, at 2:43 PM, YC wrote: > Hi all - > > how can one create a custom struct (i.e. make-struct-type or define- > struct* from ryanc) but make it work with swindle's object system? Keep the structure type descriptor (the first value which make-struct- type returns), and use swindle's struct-type->class on that descriptor to obtain a class object which describes structs of that type.  For example: (define-values (struct:my-struct make-my-struct my-struct? my-struct- get my-struct-set!)    (make-struct-type 'my-struct #f 1 0)) (define <my-struct> (struct-type->class struct:my-struct)) Now you can use <my-struct> anywhere a class object could be used in Swindle. Good luck! Will </blockquote></div>