[PRL] Racket module question

[Matthias Felleisen]

Here is what i mean: 

#lang racket/load

(module C racket
  (provide set-store retrieve-store)
  (define b (box 0))
  (define (set-store x v) (set-box! b v))
  (define (retrieve-store x) (unbox b)))

(module A racket
 (require 'C)
 (set-store 'x 5))

(module B racket 
 (require 'C 'A)
 (displayln (retrieve-store 'x)))

(require 'B)




On Jun 29, 2011, at 6:08 PM, Mitchell Wand wrote:

> 
> 
> On Wed, Jun 29, 2011 at 6:06 PM, Matthias Felleisen <matthias at ccs.neu.edu> wrote:
> 
> On Jun 29, 2011, at 6:03 PM, Mitchell Wand wrote:
> 
> > I've got two different modules (call them A and B) that cooperate by manipulating a shared store.  The API for the store is provided by a third module C.
> >
> > I'm guessing that simply requiring C in both A and  B isn't going to work, because A and B would be working with different instances of the store.
> 
> 
> You can't possibly mean something like that:
> 
> module A:
> 
>  (require C)
>  (set-store 'x 5)
> 
> module B:
> 
>  (require C)
>  (displayln (retrieve-store 'x))
> 
> 
> Because this works just fine.
> 
> Oh, really?  In that case I'm ready to  rock&roll.