> On Mar 31, 2017, at 1:00 PM, David Storrs <[email protected]> wrote: > > In Perl I can use caller() [1] to access the stack so that I can have _baz > report errors as though the error were coming from 'foo' or 'bar' as > appropriate -- which is what the user expects to see, since their code called > 'foo' or 'bar', not '_baz'. (Even better, I could report as though the error > were coming from the *caller* of foo / bar, which is the user's actual code > and the real source of the problem.)
An exception propagates upward through the calling chain. So rather than immediately using `raise-arguments-error` and launching it to the top, you could raise the error in two steps: 1) create a new error type (say, `(struct _baz-error (msg))`, so it has a unique predicate). You can also inherit from something in the `exn` hierarchy. 2) raise this error within `_baz`: `(raise (_baz-error "whoops"))` 3) catch the error within `foo` or `bar` using `with-handlers`: `(with-handlers ([_baz-error? (λ (exn) (handle-baz-error exn)]) ···)` Where `handle-baz-error` maybe re-raises the error with `raise-argument-errors` using the name of the current function. 4) Or following your "even better" idea, put the `with-handlers` in the caller of `foo` / `bar`. Here's an example of this approach: http://beautifulracket.com/basic-2/better-line-errors.html <http://beautifulracket.com/basic-2/better-line-errors.html> 5) You could extend this idea to more than two steps, where you collect other names in the calling chain on the way up. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
