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close(+Stream)

Closes the stream specified by Stream.
Stream
Integer or atom.

Description

Used to close a stream. Stream can be a symbolic stream name or a physical stream number.

When Stream is a physical stream, it is closed, but all symbolic streams associated to it still refer to it until they are either closed as well or redirected to other physical streams. As long as there are some symbolic stream names associated to a physical stream, the physical stream cannot be reused for other communication channels.

When Stream is a symbolic stream name, it gets detached from the corresponding physical stream, and the physical stream is closed (unless it was already closed).

When an attempt is made to close a system stream, event 196 is raised. To close a physical stream connected with a system stream it is therefore advisable to redirect the system stream to another physical stream. Note however, that the default handler for the event 196 first resets all system streams connected to the physical stream to their defaults and then closes the physical stream. Attempts to close the default physical stream of a system stream are ignored.

Modes and Determinism

Exceptions

(4) instantiation fault
Stream is not instantiated.
(5) type error
Stream is instantiated, but not to an integer or an atom.
(172) File is not open :
File specified by stream number Stream is not open.
(193) illegal stream specification
Stream is an illegal stream specification.
(196) trying to modify a system stream
Trying to close a system stream.

Examples

Success:
      open(file1,write,s),write(s, a(b,c)),close(s).

      [eclipse]: open(junk, write, a), set_stream(b, a),
                get_stream(a, S).

      S = 5
      yes.
      [eclipse]: close(a), open(junk1, write, X).

      X = 6       % 5 is not reused because b still points to it
      yes.
      [eclipse]: close(b), open(junk2, write, Y).

      Y = 5       % now 5 can be reused
      yes.


Error:
      close(Stream).         (Error 4).
      close("4").            (Error 5).
      close(10).             (Error 172).
      close(nostream).       (Error 193).
      close(null).           (Error 196).



See Also

open / 3, open / 4, set_stream / 2