I think the issue is that any variable, V, in a module compiled without a (set! V E) expression somewhere in it is compiled as immutable. If the only set! in the module is in a macro that has not been called yet, your variable is being compiled as immutable. If you put a set! of the variable somewhere inside the module -- even just (set! V V) as the last form in the module -- the variable should be compiled as mutable and the macro should work in its original form.
I have not tested this, so it may not be right, but it is what I recall about how set! works with modules. Carl Eastlund On Sat, Jul 10, 2010 at 5:52 AM, Skeptic . <[email protected]> wrote: > > > Hi, > I was trying to come up with a naive implementation of check-expect/test and > I found out that if a macro expands to a set! on a module-level variable > directly, an error will be given when using the macro from another module. A > simple fix seems to instead have the macro to expands to a function call that > performs the set!. > I'm not sure what to think about it and I would like to hear why it works > that way or what I have missed. > Here's what I came up with in a few minutes : > (provide check-expect test) > (define tests '()) > (define-syntax check-expect (λ (stx) (syntax-case stx () [(_ exp > res) #'(add-test (list (delay exp) res #'stx))]))) > (define add-test (λ (test) (set! tests (cons test tests)))) ; add-test is > there because having check-expect expands to set! doesn't work when called > from another module. > (define test (λ () (printf "Ran ~a checks.\n" (length tests)) (let* > ([failed (filter (λ (test) (not (equal? (force (car test)) (cadr test)))) > (reverse tests))] [nbfailed (length failed)]) (if (> nbfailed > 0) (begin (printf "~a tests failed:\n" nbfailed) > (for-each (λ (ft) (let ([ft-stx (caddr ft)]) > (printf "Actual value ~a differs from ~a, the expected > value.\n ~a\n" (force (car ft)) (cadr ft) > (format "In ~a at line ~a column ~a" (syntax-source ft-stx) (syntax-line > ft-stx) (syntax-column ft-stx))))) failed)) (printf "All test > passed!\n")) ))) _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
