<HTML><BODY>I want to have lazy-load struct. In C++ it is called proxy reference (when dereferencing return new (or cached) object loaded on demand) Ideally, it would be like (lazy-struct obj (a b c) #:loader load-data) then (define my-obj (make-ref obj "unique-id")) (displayln (obj-a my-obj)) ;; here content of my-obj should be loaded via load-data. And match pattern would also work. Now I made API with (get-field my-obj 'a), but is not Racketish. Fri, 15 Aug 2014 08:45:59 -0400 от "Alexander D. Knauth" <alexander@knauth.org>: <blockquote style="border-left:1px solid #0857A6; margin:10px; padding:0 0 0 10px;"> <div id=""> <div class="js-helper js-readmsg-msg"> <style type="text/css"></style> <div> <base target="_self" href="https://e.mail.ru/"> <div id="style_14081067690000000643_BODY"> Why not just define a new version of object-a that does that? You probably have a good reason, but what is it? Is it to change the result of struct->vector, allow (object a b c) as a match pattern to match ref, or what? On Aug 15, 2014, at 6:42 AM, Roman Klochkov <<a href="/compose?To=kalimehtar@mail.ru">kalimehtar@mail.ru</a>> wrote: > I have > (struct object (a b c)) > (struct reference (id data)) > > Let `ref' -- an instance of `reference'. > > I want, that (object-a ref) call my own (ref-get object-a ref) > > (define (ref-get accessor ref) > (unless (weak-box-value (ref-data ref)) > (set-ref-data! ref (make-weak-box (load-data (ref-id ref))))) > (accessor (weak-box-value (ref-data ref)))) > > Is it possible? > I found `impersonate-struct', but it is not struct itself (no `id' field). > I can add `prop:impersonator-of',. but how to redirect accessors? > > -- > Roman Klochkov > ____________________ > Racket Users list: > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </div> <base target="_self" href="https://e.mail.ru/"> </div> </div> </div> </blockquote> -- Roman Klochkov </BODY></HTML>