output-stream—an output stream designator. The default is standard output.
finish-output
, force-output
, and clear-output
exercise control over the internal handling of buffered stream output.
finish-output
attempts to ensure that any buffered output
sent to output-stream has reached its destination, and then returns.
force-output
initiates the emptying of any
internal buffers but does not wait for completion
or acknowledgment to return.
clear-output
attempts to abort any
outstanding output operation in progress in order
to allow as little output as possible
to continue to the destination.
If any of these operations does not make sense for output-stream, then it does nothing. The precise actions of these functions are implementation-dependent.
;; Implementation A (progn (princ "am i seen?") (clear-output)) → NIL ;; Implementation B (progn (princ "am i seen?") (clear-output)) ▷ am i seen? → NIL
*standard-output*
Should signal an error of type type-error
if output-stream is not a stream designator.