Hi Dan,
Try with this:
main.rkt:
#lang racket
(require racket/stxparam "macro.rkt" "param.rkt")
(syntax-parameterize ([dirs 123])
(mymacro))
macro.rkt:
#lang racket
(require racket/stxparam "param.rkt")
(provide mymacro)
(define-syntax (mymacro stx)
#`(printf "dirs was ~a\n" #,(syntax-parameter-value #'dirs)))
param.rkt:
#lang racket
(require racket/stxparam)
(provide dirs)
(define-syntax-parameter dirs #f)
If you want the parameter's value to be effective during the require itself,
like this:
(splicing-syntax-parameterize ([dirs 123])
(require "myfile.rkt"))
then I do not know of an easy solution. You can set a compile-time variable to
a mutable box, and set! that box, but it has some shortcomings:
1) when the file reading from the box is first compiled, the box has its
default value
2) changes to the value are no longer scoped (every set-box! overwrites the
value, so transitive requires might not see the value you expected if there are
several calls to set-box!).
Here's the code for that:
main.rkt
#lang racket
(require racket/stxparam
racket/splicing
"param.rkt")
(begin-for-syntax
(set-box! dirs 123))
(require "myfile.rkt")
myfile.rkt:
#lang racket
(require racket/stxparam
"w3.rkt")
(begin-for-syntax
(printf "dirs is ~a\n" dirs))
param.rkt:
#lang racket
(require racket/stxparam)
(provide (for-syntax dirs))
(define-for-syntax dirs (box #f))
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