Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!uakari.primate.wisc.edu!unmvax!brainerd From: brainerd@unmvax.unm.edu (Walt Brainerd) Newsgroups: comp.lang.fortran Subject: Re: EQUIVALENCE, COMPUTED GO TO in FORTRAN 88? Message-ID: <591@unmvax.unm.edu> Date: 18 Dec 89 03:09:20 GMT References: <7320@ficc.uu.net> <14178@lambda.UUCP> <7329@ficc.uu.net> Organization: University of New Mexico at Albuquerque Lines: 36 In article <7329@ficc.uu.net>, peter@ficc.uu.net (Peter da Silva) writes: > In article <14178@lambda.UUCP> jlg@lambda.UUCP (Jim Giles) writes: > > Aparently I am more concerned about it than you are - if the examples > > you gave are truly representative of the various ways PAUSE is > > implemented on systems you have access to. The only thing you have > > done is demonstrate that PAUSE _ISN'T_ a portable feature. > > PAUSE is portable. It presents the operator with a message in an appropriate > format and waits for a response. The implementation isn't portable, but that's > to be expected. I could write a similar set of #ifdefs for, oh, "OPEN". > There are many things that are standard Fortran that are not portable. PAUSE is one of them. What I mean by this is that there is nothing in the description of the language (the standard) that even hints at how it should be implemented (the semantics), except that execution is suspended and the rest of the stuff in the statement (char string or digits) must be "accessible". Apparently this means it could be flashed on a lighted display on Times Square for a nanosecond, for example. Therefore a programmer trying to write software to port to many systems cannot rely on any particular behavior. A different issue is how many of the many systems out there take somewhat the same kind of action. Even if they did, this would be some kind of "de facto" uniform conformance, not one guaranteed by the language specification, hence not something one can rely on when trying to writing portable software. > No, what you have demonstrated is that you don't understand what people use > the PAUSE statement for. Not only do you not understand C, you don't even > understand Fortran. > This is patently false, as anyone who has read this column knows (that does not mean, of couse, that I agree with him a lot!) -- Walt Brainerd Unicomp, Inc. brainerd@unmvax.cs.unm.edu 2002 Quail Run Dr. NE Albuquerque, NM 87122 505/275-0800