38 lines
1.2 KiB
Scheme
38 lines
1.2 KiB
Scheme
;; Copyright 2002, 2003 Andreas Bernauer
|
|
|
|
;; With callbacks you can create special links that are associated
|
|
;; with a function. If the user clicks on the special callback link,
|
|
;; the send-html/suspend won't return, but the function will be called
|
|
;; instead.
|
|
|
|
;; NOTE: It is not sensible to create callbacks on top level, as they
|
|
;; contain continuations. You have to create a new callback every time
|
|
;; you want to use it (inside a function).
|
|
(define (make-callback function)
|
|
(call-with-current-continuation
|
|
(lambda (exit)
|
|
(let* ((req (send/suspend (lambda (new-url)
|
|
(exit new-url)))))
|
|
(function req)))))
|
|
|
|
|
|
(define (make-annotated-callback function)
|
|
(let* ((annotated-address (make-annotated-address))
|
|
(dispatch
|
|
(lambda (req)
|
|
(let ((bindings (get-bindings req)))
|
|
(cond
|
|
((returned-via annotated-address bindings) =>
|
|
(lambda (args)
|
|
(apply function (cons req args))))
|
|
(else
|
|
(error "annotated-callback:
|
|
unexpected return values from website"))))))
|
|
(callback (make-callback dispatch)))
|
|
(lambda args
|
|
(annotated-address callback args))))
|
|
|
|
(define callback-functor
|
|
(lambda (req proc . args)
|
|
(apply proc (cons req args))))
|