Good. I'm glad we avoided the unknown boogeyman. But I don't see why you need tangle lists and these things.
Robby On Thu, Oct 20, 2011 at 10:54 AM, Neil Toronto <neil.toro...@gmail.com> wrote: > On 10/20/2011 08:08 AM, Robby Findler wrote: >> >> Well, what about the current-namespace? The output ports? It seems >> dangerous and leak introducing (possibly). >> >> I don't actually have an example where it could cause a problem tho. But >> you might try to think thru the ramifications by searing for "current-" >> in the docs. > > I still think using a thread wouldn't be a problem. But you convinced me > yesterday that it could become a problem in the future. > > So I invented parameter lists. Creating a plot pict looks like this now: > > (define saved-parameters (plot-parameters)) > (dc (λ (dc x y) > (parameterize/list ([plot-parameters saved-parameters]) > (plot/dc renderer-tree dc x y width height ...))) > width height) > > Some example tests: > > (define p1 (make-parameter 1)) > (define p2 (make-parameter 2)) > (define ps1 (parameter-list p1 p2)) > > (check-equal? (ps1) (list 1 2)) > (check-equal? (parameterize/list ([ps1 (list 10 20)]) (ps1)) > (list 10 20)) > (check-equal? (parameterize ([p1 10] [p2 20]) (ps1)) > (list 10 20)) > (check-equal? (parameterize/list ([ps1 (list 10 20)]) > (list (p1) (p2))) > (list 10 20)) > > (ps1 (list 10 20)) > > (check-equal? (ps1) (list 10 20)) > > Rules: > > ((parameter-list p ...)) = (list (p) ...) > > ((parameter-list p ...) (list v ...)) = (begin (p v) ...) > > (parameterize/list ([(parameter-list p ...) (list v ...)]) e ...) > = (parameterize ([p v] ...) e ...) > > ((parameter-list* p ... pl)) = (list* (p) ... (pl)) > > ((parameter-list-append pl ...)) = (append (pl) ...) > > I know Blake has wanted these before, so I might throw them into unstable. > > Neil T > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
