From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,c4cb2c432feebd9d X-Google-Thread: 1094ba,c4cb2c432feebd9d X-Google-Thread: 101deb,15c6ed4b761968e6 X-Google-Attributes: gid103376,gid1094ba,gid101deb,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news3.google.com!news.glorb.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: "Tom Linden" Newsgroups: comp.lang.ada,comp.lang.fortran,comp.lang.pl1 Subject: Re: Ada vs Fortran for scientific applications Date: Tue, 11 Jul 2006 07:45:42 -0700 Organization: Kednos Message-ID: References: <0ugu4e.4i7.ln@hunter.axlog.fr> <%P_cg.155733$eR6.26337@bgtnsc04-news.ops.worldnet.att.net> <6H9dg.10258$S7.9150@news-server.bigpond.net.au> <1hfv5wb.1x4ab1tbdzk7eN%nospam@see.signature> <2006052509454116807-gsande@worldnetattnet> <1kzktalo9krea$.z8n9wev45xct$.dlg@40tude.net> Mime-Version: 1.0 Content-Type: text/plain; format=flowed; delsp=yes; charset=iso-8859-15 Content-Transfer-Encoding: Quoted-Printable X-Trace: individual.net KlcDuXOSM5b+xF3xcWLoCQ1mCW0ajTovWx7IOeBkkBK+Ae1sqz User-Agent: Opera Mail(BETA2)/9.00 (Win32) Xref: g2news2.google.com comp.lang.ada:5612 comp.lang.fortran:11934 comp.lang.pl1:1979 Date: 2006-07-11T07:45:42-07:00 List-Id: On Tue, 11 Jul 2006 07:46:04 -0700, John W. Kennedy = wrote: > adaworks@sbcglobal.net wrote: >> "robin" wrote in message = >> news:z9Dsg.2740$tE5.2374@news-server.bigpond.net.au... >>> Compilers can check for uninitialized variables during compilation. >>> >> True. In fact, Ada compilers issue a warning for any variable >> that is used before a value is assigned to it. If a parameter is >> included in a method (function/procedure/subroutine) and never >> referenced, a warning is issued. Sometimes the pragma >> Normalize_Scalars is useful. Often, the correct design is to >> leave variables uninitialized until they are used so an exception >> can be raised. However, since the compiler will emit a warning >> about variables that have never been assigned a value in an algorithm= >> that tries to use it, no harm is really done since the careful = >> programmer >> will not release a program with warnings in it. >> So, I am assuming, Robin, that PL/I does something similar: a warni= ng >> for any variable that is used in a program before a value is assigned= = >> to it. > > Smart compilers may try to do so, as a by-product of optimization, but= = > PL/I is too old a design for this sort of thing to be taken for grante= d; = > there are unavoidable holes, because PL/I A) passes by reference, B) = > does not have in-out parameter declaration, and C) uses separate = > compilation and a dumb linker, making global flow analysis impossible.= PL/I on VAX has done global flow analysis since 1980. > > (Java is the only language I know of that will actually fail the compi= le = > unless it /knows/ that every variable is initialized before use in eve= ry = > possible path.) >