On Mar 13, 2012, at 1:48 PM, Robby Findler wrote:
> Do you get a stacktrace with the error?
No -- since errors are being caught by the handin server, I assume -- but I've
narrowed it down a bit by now and can offer some more specifics: In
(parameterize ([sandbox-namespace-specs
(list make-base-namespace 'hw/solutions)])
...create two evaluators...)
I was neglecting to include '2htdp/image in the namespace specs list, and
adding it eliminated the error message about accessing preferences. I also
found, in experimenting, that
* creating either one of the two evaluators alone is sufficient to
trigger the error -- make-evaluator/submission and make-module-evaluator behave
the same in this regard.
* it does not matter whether '2htdp/image is included in the allow-read
list passed to either of the make-evaluator functions.
In any case, I seem to have found my fix for the moment, but if I can help you
track down where that obscure error message originated and why, let me know and
I'll be glad to.
Incidentally, separate from the concern of my initial post: In the body of that
(parameterize ...) expression, I found i have to create the second evaluator
thus:
(make-module-evaluator (build-path asg-dir "solution.rkt") #:allow-read
'(hw/solutions))
where hw is a collection I have linked to a directory (via raco link). If I
omit the #:allow-read as I did originally (quoted below), I get this error in
the server log and via the client UI:
ERROR: file-exists?: `exists' access denied for /<path to hw
collection>/solutions.rkt
I would rather not expose my system pathnames to the end users, so I assume the
best way is to catch this kind of error explicitly in the code that creates the
evaluators. (In addition to doing the right thing by including the
#:allow-read, of course; I realized, while testing, that the student can
trigger this message if they (require...) my library name from their file.)
Does that sound about right?
My effort here is aimed at building a little framework whereby I can write up
the assignment solution in a file separate from the checker, and use my
solution in checking student code. I'd like a checker file to specify the
logic of how I want *most or all* assignments graded, so they're largely the
same from assignment to assignment, while the assignment-specific
required-names info and test cases can reside with my solution code -- the code
that any changes to the assignment would affect directly. I'll let you all
know when I get it to a point of sufficient robustness & utility to be worth
sharing. Thanks for your help.
Best,
jmj
>
> Robby
>
> On Tue, Mar 13, 2012 at 3:06 PM, Jordan Johnson <j...@fellowhuman.com> wrote:
>> Hi all,
>>
>> I'm trying to write a checker script for the handin server (which is running
>> on my Mac), and when i try handing an assignment in to it, I am getting the
>> error that read access to my preferences file is denied:
>>
>> ERROR: file-or-directory-modify-seconds: 'read' access denied for
>> /Users/myusername/Library/Preferences/org.racket-lang.prefs.rktd
>>
>> In the checker I am creating two evaluators, one using
>> make-evaluator/submission and the other using make-module-evaluator. I have
>> determined that this definition is provoking the error:
>> ;;
>> (define-values (asg-eval solution-eval)
>> (parameterize ([sandbox-namespace-specs
>> (list make-base-namespace 'hw/solutions)])
>> (values
>> (make-evaluator/submission
>> '(special intermediate)
>> '()
>> submission)
>> (make-module-evaluator (build-path asg-dir "solution.rkt")))))
>> ;;
>>
>> submission is bound by the handin server's check: macro, and asg-dir is
>> defined thus:
>> (define asg-dir (build-path server-dir "my-handin-directory-here"))
>> where server-dir is also provided by the handin server. solution.rkt is a
>> file I have written in ISL, which depends only on 2htdp/image and a library
>> I've linked as hw/solutions.
>>
>> Can you identify what may be triggering the attempt to read preferences, and
>> how I can either avoid it or grant appropriate read permissions? Thanks...
>>
>> Best,
>> Jordan
>>
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