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current_stream(?Stream)

Succeeds if Stream is a currently open stream.
?Stream
Atom, integer or variable.

Description

Used to test whether a given identifier denotes an open stream, or enumerates all currently open streams on backtracking.

When called with a variable argument, only the physical stream numbers are returned, not the symbolic aliases.

Fail Conditions

Fails if Stream is instantiated but does not denote an open stream.

Resatisfiable

Yes.

Exceptions

(5) type error
Name is instantiated, but not to an atom or integer.

Examples

Success:
    [eclipse 1]: current_stream(S).
    S = 0     More? (;) 
    S = 1     More? (;) 
    S = 2     More? (;) 
    S = 3     More? (;) 
    S = 4     More? (;) 
    S = 5     More? (;) 
    no (more) solution.

    [eclipse 2]: current_stream(output).
    yes.

    [eclipse 3]: current_stream(junk).
    no (more) solution.

See Also

open / 3, open / 4, get_stream_info / 3, get_stream / 2