<HTML><BODY>So I can write (define (make-obj stream) (define res (obj (open-output-file "out.dat"))) (define will (make-will-executor)) (will-register will res (lambda (x) (close-output-port (obj-file x)))) (thread (lambda () (let loop () (will-try-execute will) (sleep 1) (loop))))) to make my objects? Additional threads don't hinder performance, do they? Or should I somehow figure out if the thread is already running, don't run it and use common `will' for all objects? Sat, 2 Aug 2014 07:00:04 -0500 от Robby Findler <robby@eecs.northwestern.edu>: <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_14069808100000000236_BODY">One way is to set up a separate thread to do that. The reason they are not called automatically is sometimes running the procedure passed to will-register needs to access some shared state and so your program must be allowed to be in control of the timing of the executor. In this case, it sounds like you can run the executor at any time, so just creating a thread to close the port inside my-obj should work fine. Robby On Sat, Aug 2, 2014 at 6:15 AM, Roman Klochkov <<a href="/compose?To=kalimehtar@mail.ru">kalimehtar@mail.ru</a>> wrote: > Then how? > > Suppose I have > (struct obj (file)) > (define my-obj (obj (open-output-file "out.dat"))) > > What I have to write to close the file, when my-obj will be GC'ed? > > I can write > (define will (make-will-executor)) > (will-register will my-obj (lambda (x) (close-output-port (obj-file x)))) > > But as far as I understand, it will not be called until `will-execute' or > `will-try-execute' will be manually called? > > Then how to call will-try-execute when GC is collecting my-obj? > > > Sat, 2 Aug 2014 11:57:32 +0100 от Matthew Flatt <<a href="/compose?To=mflatt@cs.utah.edu">mflatt@cs.utah.edu</a>>: > > No, use the safe "will executors" API, instead. > > The unsafe finalizer API is for low-level, atomic finalization. Closing a > port can flush buffers and more, and it's not a good idea to do that in an > unsafe atomic context. > >> On Aug 2, 2014, at 11:12 AM, Roman Klochkov <<a href="/compose?To=kalimehtar@mail.ru">kalimehtar@mail.ru</a>> wrote: >> >> I have a structure, that has a filestream inside it. File have to be >> cosed, when the structure is not used anymore (so gargbage collected). >> >> Is the best way to do >> (require ffi/unsafe) >> (register-finalizer my-obj >> (lambda (x) (close-output-port (obj-file x)))) >> >> ? >> >> It seems doing right thing, but why `ffi/unsafe'? Is it OK, when my >> program actually doesn't use FFI? >> >> >> -- >> Roman Klochkov >> ____________________ >> Racket Users list: >> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> > > > > -- > 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>