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get_stream(+StreamId, ?Stream)

Succeeds if Stream is the stream to which the stream StreamId is assigned.
StreamId
Atom or integer.
Stream
Integer, atom or variable.

Description

StreamId is an existing symbolic or physical stream identifier. If Stream is a variable, it will get bound to the physical stream number corresponding to StreamId. If Stream is an existing symbolic or physical stream identifier, then the predicate succeeds iff StreamId and Stream denote the same physical stream.

The predefined symbolic system stream names are:

input, output, error, warning_output, log_output, stdin, stdout, stderr, null

Modes and Determinism

Fail Conditions

Fails if Stream is not a stream with the stream identifier StreamId

Exceptions

(4) instantiation fault
One or both of StreamId and Stream is not instantiated.
(5) type error
Stream is neither an atom, an integer nor a variable.
(5) type error
StreamId is neither an atom nor an integer.
(193) illegal stream specification
StreamId is an illegal stream specification.

Examples

Success:
      [eclipse]: get_stream(input,X).
      X = 0
      yes.

      [eclipse]: set_stream(a,input), get_stream(input,a), get_stream(a,input).
      yes.

Fail:
      set_stream(b,4), get_stream(b, 10).

Error:
      get_stream(Id, S).      (Error 4).
      get_stream(1.0,S).      (Error 5).
      get_stream(3, S).       (Error 5).
      get_stream(blah,S).     (Error 193). % does not exist



See Also

set_stream / 2