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stream-error-stream

stream-error-stream Function

Syntax:

stream-error-stream condition → stream

Arguments and Values:

condition—a condition of type stream-error.

stream—a stream.

Description:

Returns the offending stream of a condition of type stream-error.

Examples:

(with-input-from-string (s "(FOO") 
  (handler-case (read s) 
    
    
    (end-of-file (c) 
      (format nil "~&End of file on ~S." (stream-error-stream c))))) 
"End of file on #<String Stream>."

See Also:

stream-error, Chapter 9 (Conditions)

Expanded Reference: stream-error-stream​

Basic Usage​

stream-error-stream returns the offending stream from a condition of type stream-error.

(with-input-from-string (s "(FOO")
  (handler-case (read s)
    (end-of-file (c)
      (streamp (stream-error-stream c)))))
=> T

Identifying the Problematic Stream​

The returned stream can help diagnose which stream caused the error.

(with-input-from-string (s "")
  (handler-case (read-char s)
    (end-of-file (c)
      (let ((bad-stream (stream-error-stream c)))
        (list (streamp bad-stream)
              (eq bad-stream s))))))
=> (T NIL)

With end-of-file Conditions​

end-of-file is a subtype of stream-error, so stream-error-stream works on it.

(handler-case
    (read-char (make-string-input-stream ""))
  (end-of-file (c)
    (format nil "End of file on stream: ~A"
            (type-of (stream-error-stream c)))))
; Returns a string describing the stream type (implementation-dependent)