Re: [Gcl-devel] identifying string-streams

[Matt Kaufmann]

Thanks!  If I know that a given stream is either a string-stream or a
stream connected to a file (as opposed to being one of those "other
specialized streams"), then is my workaround OK (without needing your
patch)?

Regards,
Matt
   Cc: address@hidden
   From: Camm Maguire <address@hidden>
   Date: Thu, 27 Jan 2011 14:32:29 -0500
   MIME-Version: 1.0
   Content-Type: text/plain; charset=us-ascii

   Greetings!

   Alas, in traditional GCL (2.6.8, not 2.7.0), stream type detection
   is not fully implemented without workarounds as you suggest.  And
   indeed there may be other specialized streams with a NIL stream-name
   other than string-streams, as this keys off of a multi-purpose slot in
   the structure: "object1".  

   The surest way for now is:

   =============================================================================
   /tmp/y.l
   =============================================================================
   (clines "fixnum stream_mode(object sm) {return sm->sm.sm_mode;}")
   (defentry stream-mode (object) (fixnum "stream_mode"))
   (defun string-stream-p (s)
     (and (streamp s) 
          (let ((s (stream-mode s)))
            (or (= s (load-time-value (stream-mode (make-string-input-stream 
""))))
                (= s (load-time-value (stream-mode 
(make-string-output-stream))))))))
   =============================================================================

   (load (compile-file "/tmp/y.l"))

   All these fields are exposed automatically in inlinable lisp and C
   functions in the experimental branch, which I'd like to merge into cvs
   head soon.

   Take care,

   Matt Kaufmann <address@hidden> writes:

   > Hi --
   >
   > I'd be grateful if someone can answer the question below, even in the
   > negative, but I can work around the issue so please don't spend more
   > than a moment on this.
   >
   > In ANSI Common Lisp, (typep stream 'string-stream) is true when stream
   > is connected to a stream (hence not to a file).  In non-ANSI GCL, the
   > type of such a stream is 'stream, not 'string-stream, and the only way
   > I found (after considerable searching) to do such a query is as
   > follows:
   >
   > (si::stream-name stream) appears to return NIL if and only if stream
   > is a string-stream.
   >
   > QUESTION: For non-ANSI GCL, is this correct for both past and future
   > versions, or is there a better way to identify string-streams?
   >
   > Thanks.  If there is a different list I should query instead, please
   > let me know (and, my apologies).
   >
   > Regards,
   > Matt Kaufmann
   >
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   >
   >
   >
   >

   -- 
   Camm Maguire                                     address@hidden
   ==========================================================================
   "The earth is but one country, and mankind its citizens."  --  Baha'u'llah