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Syntax:
clear-input &optional input-stream => nil
Arguments and Values:
input-stream---an input stream designator. The default is standard input.
Description:
Clears any available input from input-stream.
If clear-input does not make sense for input-stream, then clear-input does nothing.
Examples:
;; The exact I/O behavior of this example might vary from implementation
;; to implementation depending on the kind of interactive buffering that
;; occurs.  (The call to SLEEP here is intended to help even out the 
;; differences in implementations which do not do line-at-a-time buffering.)
(defun read-sleepily (&optional (clear-p nil) (zzz 0))
  (list (progn (print '>) (read))
        ;; Note that input typed within the first ZZZ seconds 
        ;; will be discarded.
        (progn (print '>) 
               (if zzz (sleep zzz))
               (print '>>)
               (if clear-p (clear-input))
               (read))))
(read-sleepily)
>>  > 10
>>  >
>>  >> 20
=>  (10 20)
(read-sleepily t)
>>  > 10
>>  >
>>  >> 20
=>  (10 20)
(read-sleepily t 10)
>>  > 10
>>  > 20  ; Some implementations won't echo typeahead here.
>>  >> 30
=>  (10 30)
 
Side Effects:
The input-stream is modified.
Affected By:
Exceptional Situations:
Should signal an error of type type-error if input-stream is not a stream designator.
See Also:
Notes: None.
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