From 4588793158755748881 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fc772,b03957313f1e9325 X-Google-Attributes: gidfc772,public X-Google-Thread: f78e5,b03957313f1e9325 X-Google-Attributes: gidf78e5,public From: Michael Hudson Subject: Re: my own 'pointer type' Date: 1997/03/07 Message-ID: <5fperm$nh3@netlab.cs.rpi.edu>#1/1 X-Deja-AN: 223806430 Sender: cppmods@netlab.cs.rpi.edu References: <5fjlv7$jjl@netlab.cs.rpi.edu> X-Submission-Address: c++-submit@netlab.cs.rpi.edu X-Original-Date: Thu, 06 Mar 1997 16:44:02 +0000 Organization: University of Leicester, UK Reply-To: none@leicester.ac.uk Newsgroups: comp.lang.c++.moderated,comp.std.c++ Enno Rehling wrote: > > Just checking: > > Here's what I want to do: I want a kind of 'pointer type' that would allow > me to have something like a pointer to an object, plus additional info (an > id, for example). I figured that templates would be neat, I'd write ptr > a; and be able to access a.id, and overload the -> operator to access the > contents of A. Worked fine, up to a point: typecasts. > At one point, I had a class B derived from A, and it dawned on me that > ptr does not conform to ptr, because it's not derived from it. > What you describe will (I think) work, but there's a better way. template class MagicPtr { T *pointee; ... template operator MagicPtr () { return MagicPtr(pointee); } ... }; This will make MagicPtr almost as convertible as T*. For a full discussion of smart pointers (for that is what these things are called) read More Effective C++ by Scott Meyers. -- Regards, Michael Hudson Please don't email this address - it's not mine. [ Send an empty e-mail to c++-help@netlab.cs.rpi.edu for info ] [ about comp.lang.c++.moderated. First time posters: do this! ]