The generic function
stream-output-width
is used by the pretty printer to determine the output width when
*print-right-margin*
is
nil
. It returns
result
, the integer width of
stream
in units of ems, or
nil
if the width is not known. The default method provided by
fundamental-stream
returns
nil
.
LispWorks User Guide and Reference Manual - 21 Dec 2011