I'm trying to build a macro that will generate routing rules for
'dispatch-rules'.
(dispatch-rules) from web-server/dispatch has this form:
(dispatch-rules
(("announce-user") #:method post process-announce-user))
...more routes here...
)
This seems like it should be automatable, so I tried to write a macro
to generate these rules. I'd like
(routing announce-user)
to expand to the line above: (("announce-user") #:method post
process-announce-user))
Here's my stab at it, which is currently failing:
;; This part works if I use it directly, ie:
;; [("announce-file") #:method post (make-route msg-announce-file
announce-file*)]
;;
(define (make-route msg-handler pbuf-type)
(lambda (req)
(msg-handler (req->protobuf req pbuf-type))))
;; Let's try to generate the entire rule using the above
(define-syntax (routing stx)
(syntax-case
stx ()
([_ pbuf-type]
(with-syntax* ([type-name (format-id stx "~a*" #'pbuf-type)]
[handler-name (format-id stx "msg-~a" #'type-name)]
[route-name (symbol->string (syntax->datum
(format-id stx "~a" (syntax->datum #'pbuf-type))))]
)
#'[(route-name) #:method "post" (make-route
handler-name type-name)]
;; #'(quote [(route-name) #:method "post"
(make-route handler-name type-name)])
))))
;;(routing announce-file) ; If I use this (i.e. outside the
dispatch-rules) in combination with the 'quote' version above, I see
the correct thing
(define-values (dispatch-request url-for)
(dispatch-rules
(routing announce-file)
[("create-user") #:method post process-create-user]
...more routes here...
)
Error is:
racket network/routing.rkt
~/app/network/routing.rkt:194.2: dispatch-rules: bad syntax
in: (dispatch-rules (routing announce-file) (("create-user")
#:method post process-create-user) ...
context...:
/Applications/Racket_v6.6/collects/syntax/parse/private/runtime-report.rkt:698:0:
error/report
/Applications/Racket_v6.6/collects/syntax/parse/private/runtime-report.rkt:28:0:
call-current-failure-handler
standard-module-name-resolver
As mentioned in the comments, it does generate (the quoted form of)
the correct thing if I:
1) inside the macro, comment in the 'quote' line and comment out the
line above it
2) comment OUT the '(routing announce-file) that is inside dispatch-rules
3) comment IN the (routing announce-user) line that is just above dispatch-rules
My suspicion is that dispatch-rules is a macro and so my macro is not
being expanded inside another macro. That's not how I thought macros
worked, though, so now I'm really puzzled.
Can anyone clarify this for me?
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