* Evaluating definitions from another thread @ 2024-05-10 20:15 Panicz Maciej Godek 2024-05-10 20:19 ` Per Bothner 0 siblings, 1 reply; 6+ messages in thread From: Panicz Maciej Godek @ 2024-05-10 20:15 UTC (permalink / raw) To: kawa [-- Attachment #1: Type: text/plain, Size: 328 bytes --] Hi, I've noticed that when I call (future (eval '(define x 5))) then the variable x remains unbound after the execution - even though when I invoke (eval '(define x 5)), x gets bound to 5 as expected. Is there a way to have evaluated definitions introduce new bindings regardless of the thread they're being evaluated from? ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Evaluating definitions from another thread 2024-05-10 20:15 Evaluating definitions from another thread Panicz Maciej Godek @ 2024-05-10 20:19 ` Per Bothner 2024-05-10 21:03 ` Panicz Maciej Godek 0 siblings, 1 reply; 6+ messages in thread From: Per Bothner @ 2024-05-10 20:19 UTC (permalink / raw) To: Panicz Maciej Godek, kawa On 5/10/24 1:15 PM, Panicz Maciej Godek via Kawa wrote: > Hi, > > I've noticed that when I call > > (future (eval '(define x 5))) > > then the variable x remains unbound after the execution > - even though when I invoke (eval '(define x 5)), x gets bound to 5 as > expected. This might work: (define x #f) (future (eval '(set! x 5))) -- --Per Bothner per@bothner.com http://per.bothner.com/ ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Evaluating definitions from another thread 2024-05-10 20:19 ` Per Bothner @ 2024-05-10 21:03 ` Panicz Maciej Godek 2024-05-11 0:49 ` Per Bothner 0 siblings, 1 reply; 6+ messages in thread From: Panicz Maciej Godek @ 2024-05-10 21:03 UTC (permalink / raw) To: Per Bothner; +Cc: kawa [-- Attachment #1: Type: text/plain, Size: 984 bytes --] pt., 10 maj 2024 o 22:19 Per Bothner <per@bothner.com> napisał(a): > > > On 5/10/24 1:15 PM, Panicz Maciej Godek via Kawa wrote: > > Hi, > > > > I've noticed that when I call > > > > (future (eval '(define x 5))) > > > > then the variable x remains unbound after the execution > > - even though when I invoke (eval '(define x 5)), x gets bound to 5 as > > expected. > > This might work: > > (define x #f) > (future (eval '(set! x 5))) > Thanks, it does the trick for simple cases. I currently scan for the appearance of "define", then extract for the symbol and build a binding, and then evaluate `(set! ,symbol (let () ,expression ,symbol)) but if I wanted to handle a more general case (such as a begin form containing some definitions), I'd probably need to implement something closer to a full evaluator, which makes me wonder whether the above behavior (with variables not being bound from other threads) is actually desired? ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Evaluating definitions from another thread 2024-05-10 21:03 ` Panicz Maciej Godek @ 2024-05-11 0:49 ` Per Bothner [not found] ` <CAMFYt2bqd3LNLPFgdhpaDrSkdM_SLGCGYnSqs0-gw0Z9n-OFqw@mail.gmail.com> 0 siblings, 1 reply; 6+ messages in thread From: Per Bothner @ 2024-05-11 0:49 UTC (permalink / raw) To: Panicz Maciej Godek; +Cc: kawa On 5/10/24 2:03 PM, Panicz Maciej Godek wrote: > which makes me wonder whether the above behavior (with variables not being bound from other threads) is actually desired? Yes. If a child thread needs to define new variables in the parent thread, you're almost certainly doing something wrong. More generally: Most of the time people use eval, they shouldn't. -- --Per Bothner per@bothner.com http://per.bothner.com/ ^ permalink raw reply [flat|nested] 6+ messages in thread
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* Re: Evaluating definitions from another thread [not found] ` <4c435a3e-0517-46c5-b541-88f1355dfe4b@bothner.com> @ 2024-05-12 21:08 ` Panicz Maciej Godek 2024-05-12 21:22 ` Per Bothner 0 siblings, 1 reply; 6+ messages in thread From: Panicz Maciej Godek @ 2024-05-12 21:08 UTC (permalink / raw) To: Per Bothner, kawa [-- Attachment #1: Type: text/plain, Size: 2675 bytes --] sob., 11 maj 2024 o 17:44 Per Bothner <per@bothner.com> napisał(a): > If you allow the user to evaluate arbitrary expressions, that should be > done in a separate > context (environment) than GRASP itself. The user context should not > inherit everything from > the GRASP context; only deliberately exported bindings, mostly read-only. > And the user context > should not be able to add or modify arbitrary bindings in the GRASP > context; only bindings > that the GRASP engine deliberately amkes available to the eval context. > I agree that, at some point, this will need to be addressed - in particular, when people start sharing extensions that they write, I'll need to create a model for managing access to particular parts of the system. However, at this moment coming up with a compelling way of creating extensions is much more important. > This is security 101. Of course if you just want to make some someware for > yourself to > learn or play around with, do what you like. But if you want to write > software for others > to use, you need to consider security issues. > > If you want each evaluation to be performed on a separate thread, then you > need to consider > how things are synchronized: How updates in the eval thread cause changes > in the GRASP engine. > It is possible that using parameters will "do the right thing" - but I > wouldn't count on it. > > Today I developed the following subclass of ThreadLocation: https://github.com/panicz/grasp/compare/main...shared-parameters The idea is that the values stored in the thread locations are themselves SharedLocations. According to my test, they behave as expected: (define x (make-shared-parameter 'x 0)) (parameterize ((x 1)) (future (begin (sleep 1) (display "changing x from ") (display (x)) (set! (x) 2) (display " to ") (display (x)) (newline))) (display "inner value of x: ") (display (x)) (newline) (sleep 2) (display "inner value of x after 2 seconds: ") (display (x)) (newline) ) (display "outer value of x: ") (display (x)) (newline) The output produced by running the above program is inner value of x: 1 changing x from 1 to 2 inner value of x after 2 seconds: 2 outer value of x: 0 whereas if - instead of using "shared parameters", I use the regular parameters, I get inner value of x: 1 changing x from 1 to 2 inner value of x after 2 seconds: 1 outer value of x: 0 I didn't quite understand why the constructor of SharedLocation requires a timestamp, and I passed it (java.lang.System:currentTimeMillis). Is that OK? ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Evaluating definitions from another thread 2024-05-12 21:08 ` Panicz Maciej Godek @ 2024-05-12 21:22 ` Per Bothner 0 siblings, 0 replies; 6+ messages in thread From: Per Bothner @ 2024-05-12 21:22 UTC (permalink / raw) To: Panicz Maciej Godek, kawa On 5/12/24 2:08 PM, Panicz Maciej Godek wrote: > I didn't quite understand why the constructor of SharedLocation requires a timestamp, and I passed it (java.lang.System:currentTimeMillis). > Is that OK? No. It is not an actual timestamp - more of a version number. (The fact that 'timestamp' is an int and currentTimeMillis is a long should tell you that currentTimeMillis() is not a suitable value for 'timestamp'.) The timestamp is used to control whether a binding is shared. It's been so long since I wrote this code, I don't remember precisely how it works. You can look at the code. -- --Per Bothner per@bothner.com http://per.bothner.com/ ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-05-12 21:23 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-05-10 20:15 Evaluating definitions from another thread Panicz Maciej Godek 2024-05-10 20:19 ` Per Bothner 2024-05-10 21:03 ` Panicz Maciej Godek 2024-05-11 0:49 ` Per Bothner [not found] ` <CAMFYt2bqd3LNLPFgdhpaDrSkdM_SLGCGYnSqs0-gw0Z9n-OFqw@mail.gmail.com> [not found] ` <4c435a3e-0517-46c5-b541-88f1355dfe4b@bothner.com> 2024-05-12 21:08 ` Panicz Maciej Godek 2024-05-12 21:22 ` Per Bothner
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