Re: unread more than one char

On Mon, 08 Oct 2007 16:38:08 -0400, Alberto Riva <ariva@xxxxxxxxxxxxxx> wrote:

What about:

(defun stream-backup (stream n)
(file-position stream
(- (file-position stream) n)))

The standard doesn't require streams to be able to represent the
notion of file position, i.e. what FILE-POSITION returns could be NIL,
or trying to change the file position doesn't have to succeed.

Also it says (in the FILE-POSITION dictionary entry) that for "a
character file, performing a single READ-CHAR or WRITE-CHAR operation
may cause the file position to be increased by more than 1."

Edi.

--

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