That worked. Thank you Matthew. ~Leif Andersen
On Mon, Dec 14, 2015 at 4:09 PM, Matthew Flatt <[email protected]> wrote: > The main problem is that you need to attach the 'not-free-identifier=? > property to the syntax object produced by your rename transformer: > > (begin-for-syntax > (struct string-box (str) > #:mutable > #:property prop:rename-transformer > (lambda (inst) > (syntax-property > (if (string-box-str inst) > #'string1 > #'string2) > 'not-free-identifier=? > #t)))) > > Otherwise, `current-str` is created as an alias to the binding of the > initial result from `(string-box #t)`. That binding alias effectively > overrides rename transformer. > > > A second problem is that you want `(syntax-e #'value)` instead of just > `#'value`. > > > At Mon, 14 Dec 2015 15:37:13 -0500, Leif Andersen wrote: >> Hello, >> >> I am trying to use a struct that is both mutable, and has >> prop:rename-transformer, to create a mutable rename transformer. I am >> able to update the value in the struct, and that update gets reflected >> properly when I do `syntax-local-value/immediate`, but >> `syntax-local-value` seems to keep around the previous definition. >> >> Is prop:rename-transformer or syntax-local-value supposed to cache its >> result, or would this be a bug? >> >> My code so far is here: http://pasterack.org/pastes/41342 >> >> ``` >> #lang racket >> >> (define-syntax string1 "hello") >> (define-syntax string2 "world") >> >> (begin-for-syntax >> (struct string-box (str) >> #:mutable >> #:property prop:rename-transformer >> (lambda (inst) >> (if (string-box-str inst) >> #'string1 >> #'string2)))) >> (define-syntax (string-lookup stx) >> (syntax-case stx () >> [(_ id) >> #`'#,(syntax-local-value #'id)])) >> (define-syntax (string-set! stx) >> (syntax-case stx () >> [(_ box value) >> (begin >> (define-values (x y) (syntax-local-value/immediate #'box)) >> (set-string-box-str! x #'value) >> #'(void))])) >> >> (define-syntax current-str (string-box #t)) >> (string-lookup current-str) >> (string-set! current-str #f) >> (string-lookup current-str) >> ``` >> >> Thank you for your help. >> >> ~Leif Andersen >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Racket Developers" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/racket-dev/CAAVaeEBxrRT1soNDP5xmrJnaYwfc49qUA >> N9P44qEqudggjUmgA%40mail.gmail.com. >> For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Racket Developers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-dev/566f2ffc.4e09620a.205ee.fffff772SMTPIN_ADDED_MISSING%40gmr-mx.google.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-dev/CAAVaeEAHS6x7Bxjk17EO3RxkdfngLLh1rKR0J%2BhnVMN107GhJQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
