Avoiding consing when translating numbers to strings

["Robert W. Kerns" <RWK%fuji.ila.dialnet.symbolics.com@RELAY.CS.NET>]

    Date: Thu, 2 Mar 89 10:06 CST
    From: ai.gooch@MCC.COM (William D. Gooch)

    FYI - you might want to try the following approach:

    (defparameter *temp-string*
		  (make-array 10 :element-type 'string-char :fill-pointer 0))

    (defun examine-number (num)
      ;; 1Protect the global parameter - format can set its first argument
0      (let ((outstr *temp-string*))
	 (setf (fill-pointer outstr) 0)
	 (format outstr "~F" num)
	 ;; 1then deal with the string (in outstr)
0	 ))

    This won't get you away from the bignum consing Barry mentioned, but it avoids
    the need to stack-allocate a new string each time, minimizing the overhead of
    building the strings.  Probably will speed things up a bit.  You have to be 
    careful because of format's modifying the global's contents in place.  I like 
    to use this approach for short-lived things such as mouse documentation strings.

The problem with this approach is that it is not reentrant.
Remember, the Symbolics system DOES have multiple processes,
and c-m-Suspend, etc.  A better way to accomplish the same
thing is to make a temp-string resource.