I left off a "syntax": it should be (lambda (o) (syntax-case o () (_ #'(raise <>)))). And then Issue 1 disappears =)
But issue 2 is harder... it would be solved by ikarus's import form (i could define the library name once and import it), assuming calling import in a transformer makes the imports available at all phases. but I don't see a way to avoid writing the library's name twice in portable r6rs. On Sun, Jun 14, 2009 at 10:26 PM, Ramana Kumar<ramana.ku...@gmail.com> wrote: > Ah I think this variation on what I sent below will work! > Instead of (identifier-syntax (raise <>)) I can use > (lambda (o) (syntax-case o () (_ (raise <>)))) > > There are two minor defects with this whole approach - do you know how > they might be fixed? > 1. I'm using make-who-condition instead of my own new condition type > because constructing a condition defined in the test script would be > an out of context error... but it would be better to use a custom > condition so I don't accidentally skip a legitimate who condition. > 2. I have to write the (library-being-tested) name twice - once in the > import line of the script and once in the call to environment in > define-missing-exports. Can I have it in only one place? > > On Sun, Jun 14, 2009 at 9:50 PM, Ramana Kumar<ramana.ku...@gmail.com> wrote: >> I thought this code would do what you say is impossible (I do believe >> you, though =P). The problem it runs into is that the call to raise >> (produced by the identifier-syntax) isn't necessarily evaluated first >> in an offending expression. (And if you raise the exception in the >> transformer rather than creating an identifier-syntax, it doesn't get >> caught by the with-exception-handler in test.) There may be bigger >> problems with it, though - if you feel like educating, let me know if >> you see any. >> >> (define-syntax define-missing-exports >> (lambda (o) >> (syntax-case o () >> ((_ var ...) >> #`(begin . >> #,(let rec ((ls #'(var ...))) >> (cond >> ((null? ls) '()) >> ((call/cc >> (lambda (k) >> (with-exception-handler >> (lambda (x) (k (not (undefined-violation? x)))) >> (lambda () (eval (syntax->datum (car ls)) >> (environment '(library-being-tested))))))) >> (rec (cdr ls))) >> (else >> `(,#`(define-syntax #,(car ls) >> (identifier-syntax (raise >> (make-who-condition '#,(car ls))))) >> . ,(rec (cdr ls))))))))))) >> >> (define-missing-exports set of all possible exports from the library >> being tested) >> >> (define-syntax test >> (syntax-rules () >> ((_ expr) >> (call/cc >> (lambda (k) >> (with-exception-handler >> (lambda (x) >> (if (who-condition? x) >> (begin >> (display (string-append "missing export: " >> (symbol->string (condition-who x)))) >> (newline) >> (k)) >> (raise-continuable x))) >> (lambda () expr))))))) >> >> >> On Sun, Jun 14, 2009 at 9:25 PM, Abdulaziz Ghuloum<aghul...@gmail.com> wrote: >>> >>> On Jun 14, 2009, at 2:10 PM, Ramana Kumar wrote: >>> >>>>> So, you have a library that may or may not export a macro, say let^, >>>>> and you have an expression that may or may not reference let^. If >>>>> the expression references let^, and let^ was not exported, which >>>>> would normally result in a syntax error, you want to defer the error >>>>> until run time instead of being signaled at macro-expansion time. >>>> >>>> I actually don't want the error at all - I want to detect that let^ is >>>> not exported and therefore remove the expression that references it >>>> (or replace it with something). This can happen at macro expansion >>>> time. Still not possible? >>> >>> It's the same thing. You want to handle the syntax-error exception by >>> replacing the offending expression with another one of your choice. >>> The replacement may be just #f or (asserion-violation 'foo "unbound") >>> or whatever. Still, not possible to do correctly without hacking on >>> psyntax. >>> >>> Aziz,,, >>> >>> >> >
