I may be completely misunderstanding something here, but don't you have to use equal? and not eq? for record structures?
K. On Wed, Dec 16, 2015 at 10:09 PM, Jörg F. Wittenberger < joerg.wittenber...@softeyes.net> wrote: > Ah, great to learn. > > a) You are right: Per SRFI-69 it is actually undefined. Per chicken > manual it returns the new value associated with key. > > As I've seen the latter (e.g. in the iup egg) actually being used, we > might at least want to keep the behavior in chicken. > > b) But does not matter much. I ran into this originally from > hash-table-ref signaling a missing key. > > The attached, modified test case fails because it i) does not find the > key object hence hash-table-fold'ing the tree to ii) find an association > with the very key the lookup failed for before. > > My hypothesis (after lightly reading the srfi-69.scm source) that the > eq?-hash procedure produces a different hash value for the lookup before > and after the mutation. Hence the lookup fails while walking the tree > succeeds. > > /Jörg > > Am 16.12.2015 um 21:55 schrieb Peter Bex: > > On Wed, Dec 16, 2015 at 09:47:31PM +0100, Jörg F. Wittenberger wrote: > >> Hi, > >> > >> I always assumed that (make-hash-table eq?) would create a hash table > >> usable with arbitrary chicken objects as keys. > >> > >> That is especially structures like objects created via define-record > >> should be valid as keys. That is: referencing the table using the very > >> same object (comparing eq? to the key object of the insert operation) > >> will succeed. > >> > >> However this fails for me. At least after the key object was mutated > >> between insert and reference time. > >> > >> See attached test case. > >> > >> Am I trying something illegal here? > >> > >> Thanks > >> > >> /Jörg > > > >> (use srfi-69) > >> > >> (define objtbl (make-hash-table eq?)) > >> > >> (define (register! obj arg) > >> (hash-table-update! objtbl obj identity (lambda () (list obj arg)))) > >> > >> (assert (eq? (register! 1 1) (register! 1 2))) > > > > I believe the return value of hash-table-update! is undefined. > > > > Cheers, > > Peter > > > > > _______________________________________________ > Chicken-users mailing list > Chicken-users@nongnu.org > https://lists.nongnu.org/mailman/listinfo/chicken-users > >
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