With the "racket/engine" module, is the "engine" procedure supposed to
capture the Racket parameter values that will be used for the proc when
"engine-run" is applied? Rather than the parameters coming from the
dynamic extent in which "engine-run" is applied?
The example below shows that parameters don't work with engines as I'd
originally assumed. (The parts about custodians are because that's what
I was originally debugging.)
#lang racket/base
(require racket/engine
racket/file)
(printf "with engine as i'd expect...\n")
(let ((temp-path (make-temporary-file "xxx~A"))
(temp-port #f))
(let* ((cust (make-custodian (current-custodian)))
(eng (engine (lambda (disable-suspend)
(if (eq? (current-custodian) cust)
(printf "OK: current-custodian is cust\n")
(printf "FAIL: current-custodian is not
cust\n"))
(set! temp-port
(open-output-file temp-path #:exists
'replace))))))
(or (parameterize ((current-custodian cust))
(engine-run 3000 eng))
(error "engine-run timed out"))
(custodian-shutdown-all cust))
(if (port-closed? temp-port)
(printf "OK: port was closed\n")
(printf "FAIL: port was not closed\n")))
;; with engine as i'd expect...
;; FAIL: current-custodian is not cust
;; FAIL: port was not closed
(printf "with engine capturing parameters early...\n")
(let ((temp-path (make-temporary-file "xxx~A"))
(temp-port #f)
(another-param (make-parameter 'initial)))
(let* ((cust (make-custodian (current-custodian)))
(eng (parameterize ((current-custodian cust)
(another-param 'around-engine))
(engine (lambda (disable-suspend)
(if (eq? (current-custodian) cust)
(printf "OK: current-custodian is cust\n")
(printf "FAIL: current-custodian is not
cust\n"))
(printf "(another-param) = ~S\n"
(another-param))
(set! temp-port
(open-output-file temp-path #:exists
'replace)))))))
(or (parameterize ((another-param 'around-engine-run))
(engine-run 3000 eng))
(error "engine-run timed out"))
(custodian-shutdown-all cust))
(if (port-closed? temp-port)
(printf "OK: port was closed\n")
(printf "FAIL: port was not closed\n")))
;; with engine capturing parameters early...
;; OK: current-custodian is cust
;; (another-param) = around-engine
;; OK: port was closed
Thanks,
Neil V.
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