Paramters and Eval

a-file.rkt

#lang racket

(provide (struct-out foo)
         my-param)

(require file/convertible)

(define my-param (make-parameter "hello"))

(struct foo ()
  #:property prop:convertible
  (λ (s type default)
    (match type
      ['silly
       (my-param)]
      [_ default])))

another-file.rkt

#lang racket

(require racket/sandbox
         file/convertible
         "a-file.rkt")

(define my-eval
  (make-module-evaluator
   #:allow-for-require '("a-file.rkt")
   '(module foo racket
      (require "a-file.rkt")
      (define a-val (foo))
      (provide a-val))))

(define that-val (my-eval 'a-val))
(parameterize ([my-param "hijacked..."])
  (convert that-val 'silly))

(define that-other-val (foo))
(parameterize ([my-param "hijacked..."])
  (convert that-other-val 'silly))

(module test racket
  (require "a-file.rkt")
  (provide another-val)
  (define another-val (foo)))
(require 'test)
(parameterize ([my-param "hijacked..."])
  (convert another-val 'silly))