Re: Bug in (remhash) ??

At 09:19 AM 5/3/03 +0000, lcluke wrote:
>Am I going nuts, or is this a bug in (remhash) ? It doesn't seem to
>remove the entry from the hash table.
>
>(setf a-hash (make-hash-table))
>
>#<HASHTABLE 0/211>
>
>(setf (gethash 'A_TEST a-hash) 'HASH_TABLE_ENTRY)
>
>HASH_TABLE_ENTRY
>
>(gethash 'A_TEST a-hash)
>
>HASH_TABLE_ENTRY
>T
>
>(remhash 'A_TEST a-hash)
>T
>
>(gethash 'A_TEST a-hash)
>HASH_TABLE_ENTRY
>T

It's a bug.

Here's a patch I came up with.

--------------------------------

(in-package :lisp)

;;; Problem:

;;; (setq (make-hash-table))
;;; (setf (gethash 'fred x) 5)
;;; (remhash 'fred x)
;;; (gethash 'fred x) --> 5

;;; Solution:  DELETE-KEY-VALUE was not testing against the real key
;;; all the time

(defun delete-key-value (list key test)
   (if (null list)
       list
     ;; used to be (funcall test key (car list))
     (if (funcall test key (if (consp (car list)) (caar list) (car list)))
         (cddr list)
         (do* ((x list (cddr x))
               (y (cddr list) (cddr y))
               (hkey (car y) (car y)))
             ((null y) list)
           (if (consp hkey)
               (setf hkey (car hkey)))
           (if (funcall test key hkey)
               (rplacd (cdr x) (cddr y)))))))





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