+(defun replace-all (string part replacement &key (test #'char=) stream)
+ "Returns a new string in which all the occurences of the part
+is replaced with replacement. [FROM http://cl-cookbook.sourceforge.net/strings.html#manip]"
+ (let ((out (or stream (make-string-output-stream))))
+ (loop with part-length = (length part)
+ for old-pos = 0 then (+ pos part-length)
+ for pos = (search part string
+ :start2 old-pos
+ :test test)
+ do (write-string string out
+ :start old-pos
+ :end (or pos (length string)))
+ when pos do (write-string replacement out)
+ while pos)
+ (unless stream
+ (get-output-stream-string out))))
+
+
+(defun filter-plist (plist &rest keys-to-remove)
+ "Returns a copy of the given plist with indicated key-value pairs
+removed. keys are searched with #'MEMBER"
+ (declare (dynamic-extent keys-to-remove))
+ (when plist
+ (loop for (k v . rest) = plist then rest
+ unless (member k keys-to-remove)
+ collect k and collect v
+ while rest)))
+
+(defmacro make-weak-hash-table (&rest args)
+ "Creates a weak hash table for use in a cache."
+ `(progn
+
+ ;;NB: These are generally used for caches that may not have an alternate
+ ;;clearing mechanism. If you are on an implementation that doesn't support
+ ;;weak hash tables then you're memory may accumulate.
+
+ #-(or sbcl allegro clisp lispworks)
+ (warn "UNSAFE! use of weak hash on implementation without support. (see clsql/sql/utils.lisp to add)")
+
+ (make-hash-table
+ #+allegro :values #+allegro :weak
+ #+clisp :weak #+clisp :value
+ #+lispworks :weak-kind #+lispworks :value
+ #+sbcl :weakness #+sbcl :value
+ ,@args)
+ ))