From rz48@rz.uni-karlsruhe.de Sat Dec 21 19:52:22 1996 Received: from nz11.rz.uni-karlsruhe.de (nz11.rz.uni-karlsruhe.de [129.13.64.7]) by dkuug.dk (8.6.12/8.6.12) with ESMTP id TAA03228 for ; Sat, 21 Dec 1996 19:52:20 +0100 Message-Id: <199612211852.TAA03228@dkuug.dk> Received: from ry73.rz.uni-karlsruhe.de by nz11.rz.uni-karlsruhe.de with SMTP (PP); Sat, 21 Dec 1996 19:52:08 +0100 Received: by ry73.rz.uni-karlsruhe.de (1.38.193.4/16.2) id AA14818; Sat, 21 Dec 1996 19:52:07 +0100 Subject: PURE/ELEMENTAL for C procedures? To: sc22wg5-interop@ncsa.uiuc.edu, sc22wg5@dkuug.dk Date: Sat, 21 Dec 1996 19:52:06 +0100 (CET) From: hennecke@rz.uni-karlsruhe.de (Michael Hennecke) Reply-To: hennecke@rz.uni-karlsruhe.de (Michael Hennecke) X-Mailer: ELM [version 2.4 PL23] Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Content-Length: 1659 F95 restricts PURE and ELEMENTAL to subprograms, and places a number of restrictions on the (Fortran) definition of such subprograms (e.g. no print-stmt or other external I/O shall appear). This allows compile-time checking of some of the factors that may prevent the PUREness of such subprograms. As it stands, a procedure defined by means of C which has an explicit interface (with the BIND(C) prefix) is not allowed to have the PURE or ELEMENTAL attribute, because it is not a subprogram. It is also not possible to ``hide'' this procedure defined by means of C in a PURE (Fortran) wrapper subprogram because all references to procedures within such a PURE subprogram must also be pure. QUESTION: Should this restriction be relaxed, simply believing the programmer who specifies PURE in an explicit interface for a procedure even if this case compile-time checks are, in general, impossible? Needless to say that writing down the words to say that the results are undefined if the procedure actually is not PURE will be a difficult task... Best regards, Michael ====================================================================== Michael Hennecke http://www.uni-karlsruhe.de/~Michael.Hennecke/ ---------------------------------------------------------------------- University of Karlsruhe RFC822: hennecke@rz.uni-karlsruhe.de Computing Center (G20.21 R210) No longer on BITNET :-( Zirkel 2 * P.O. Box 69 80 Phone: +49 721 608-4862 D-76128 Karlsruhe Fax: +49 721 32550 ======================================================================