From 964767553222300797 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,a0fcd8899dc05427 X-Google-Attributes: gidf78e5,public From: JdeBP@jba.co.uk (Jonathan de Boyne Pollard) Subject: Re: Implicit smart-to-dumb pointer conversions Date: 1996/06/12 Message-ID: <4pm8e7$55m@silver.jba.co.uk>#1/1 X-Deja-AN: 159812354 references: <009A31CF34AEC020.4980D61E@ittpub.nl> <4ottpt$4i4@kelly.teleport.com> <4pihj9$bd8@news2.delphi.com> x-original-date: 12 Jun 1996 12:07:51 +0100 organization: JBA Software Products, Studley, England. x-auth: PGPMoose V1.1 PGP comp.std.c++ reply-to: JdeBP@donor2.demon.co.uk newsgroups: comp.std.c++ originator: austern@isolde.mti.sgi.com Greg Colvin (gregor@netcom.com) wrote: | It is not hard to write a conforming auto_ptr that throws an exception when | you dereference a dangling pointer, though there is some performance cost. | A simple version just implements a reference counted pointer and puts an | auto_ptr interface on it. You could use such a version for debugging and | switch to a more efficient version for production code. Except that you are not allowed to do that. auto_ptr is in namespace std, and programs are not allowed to declare names in that namespace [lib.reserved.names]. So you are stuck with whatever auto_ptr is provided to you by the implementation. Yes, with conditional compilation, and judicious use of typedefs, you could get around this. #if defined(USE_DEBUGGING_AUTO_PTR) typedef throw_exception_auto_ptr my_auto_ptr ; #else typedef std::auto_ptr my_auto_ptr ; #endif However, the disadvantage of this is that your code is now less legible and thus less maintainable by other people, since it now does not reference the "standard" auto_ptr class. If you ask me, I think that auto_ptr is not ready for standardisation. Let the multiple different variants on auto_ptr be provided by third-party libraries, and wait a few years to see what particular variant becomes popular. Then standardise that one. --- [ comp.std.c++ is moderated. To submit articles: Try just posting with your newsreader. If that fails, use mailto:std-c++@ncar.ucar.edu comp.std.c++ FAQ: http://reality.sgi.com/austern/std-c++/faq.html Moderation policy: http://reality.sgi.com/austern/std-c++/policy.html Comments? mailto:std-c++-request@ncar.ucar.edu ]