C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Smart pointer vs handle class          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message newbiecpp Guest Posted: Sat Oct 23, 2004 2:20 pm    Post subject: Smart pointer vs handle class After study smart pointer and handle class idioms, I have a few questions. In smart pointer, you forward all the operations to an object which is pointed by the smart pointer. In handle class, you copy interface of the object into handle class and put some code there then forward operations to the object. Andrew Koenig prefers handle class idiom over smart pointer idiom in his book. But I don't understand why? To me, smart pointer idiom looks simpler. In handle class idiom, you have to write lots of code there. Do I miss something? Thanks for your opinions. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top kwikius Guest Posted: Mon Oct 25, 2004 1:39 pm    Post subject: Re: Smart pointer vs handle class "newbiecpp" <newbiecpp (AT) yahoo (DOT) com> wrote Quote: After study smart pointer and handle class idioms, I have a few questions. In smart pointer, you forward all the operations to an object which is pointed by the smart pointer. In handle class, you copy interface of the object into handle class and put some code there then forward operations to the object. Andrew Koenig prefers handle class idiom over smart pointer idiom in his book. But I don't understand why? To me, smart pointer idiom looks simpler. In handle class idiom, you have to write lots of code there. Do I miss something? Thanks for your opinions. A handle is more flexible. You can change the actual shared object, while references to it remain valid. Useful eg if you want to convert an object to an 'active' state , by replacing (say) a dumb object by a smart one. Also where you may be swapping data in and out of memory etc, when the actual address will change. Downside is that it is usually slower than a smart-pointer, as you need to map the handle somehow. regards Andy Little [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top kanze@gabi-soft.fr Guest Posted: Tue Oct 26, 2004 4:20 am    Post subject: Re: Smart pointer vs handle class "newbiecpp" <newbiecpp (AT) yahoo (DOT) com> wrote Quote: After study smart pointer and handle class idioms, I have a few questions. In smart pointer, you forward all the operations to an object which is pointed by the smart pointer. In handle class, you copy interface of the object into handle class and put some code there then forward operations to the object. Andrew Koenig prefers handle class idiom over smart pointer idiom in his book. But I don't understand why? To me, smart pointer idiom looks simpler. In handle class idiom, you have to write lots of code there. Do I miss something? The smart pointer idiom is easier to implement. The handle idiom is easier to (re)use. My own preference depends a lot on the classes semantics. If the identity of elements of the class is significant, I'll use the smart pointer idiom, since this makes it clear to the user that he does have reference semantics. If the class should appear to have value semantics (with either deep copy or copy on write), I'll definitely use a handle. But there are a lot of cases which could go either way. -- James Kanze GABI Software http://www.gabi-soft.fr Conseils en informatique orientée objet/ Beratung in objektorientierter Datenverarbeitung 9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34 [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ Language (Moderated) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.