[plt-scheme] passing-on keyword arguments

Thanks, Eli.  I used your suggestion and it worked for me purposes.

--rob


On Tue, Mar 18, 2008 at 3:53 PM, Eli Barzilay <eli at barzilay.org> wrote:
> On Mar 18, Rob Hunter wrote:
>  > Let me elaborate: If, for example, I had a way of passing an
>  > "absent" value for a keyword argument, then I could do this with
>  > functions:
>  >
>  > (define (inner #:x [x 10]) (* x x))
>  >
>  > (define (outer #:x [x ABSENT-VAL]) (+ (inner #:x x) 5))
>  >
>  > The semantics of ABSENT-VAL are such that if it is passed as a
>  > keyword argument's val, then it as if I never set that keyword arg,
>  > and thus the default value for it would be used.
>
>  It's a cute idea, but it only covers one corner.  Specifically in this
>  case, I think that another goal should be to avoid repeating `inner's
>  interface.  There is a way to do that now, but it's not convenient:
>
>   (define outer
>     (make-keyword-procedure
>      (lambda (kws vals . args)
>        (+ (keyword-apply inner kws vals args) 5))))
>
>  I think that I know how to make it easier, allowing something like
>  this:
>
>   (define (outer args ...)
>     (+ (inner args ...) 5))
>
>  to do the same, but it'll take some work to implement.
>
>  --
>           ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
>                   http://www.barzilay.org/                 Maze is Life!
>