Next: ref-iou-sfh-bos, Previous: ref-iou-sfh-cis, Up: ref-iou-sfh [Contents][Index]
current_output(Stream)
unifies Stream with the current output
stream.
user_output
, then
telling(S)
unifies S with user
. Otherwise,
if the current output stream was opened by tell(F)
, then
telling(S)
unifies S with F. Otherwise, if
the current output stream was opened by open/[3,4]
, then
telling(S)
unifies S with the corresponding stream
object.
telling/1
can be used to verify that a section of code leaves
the current output stream unchanged as follows:
/* nonvar(FileNameOrStream), */ tell(FileNameOrStream), … telling(FileNameOrStream)
WARNING: The sequence
telling(File), … set_output(File),will signal an error if the current output stream was opened by
tell/1
. The only sequences that are guaranteed to succeed aretelling(FileOrStream), … tell(FileOrStream)and
current_output(Stream), … set_output(Stream)