C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Re: can this be done in C? (a = new B, where B is an instanc          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Chandra Shekhar Kumar Guest Posted: Thu Jun 26, 2003 10:31 pm    Post subject: Re: can this be done in C? (a = new B, where B is an instanc Quote: shape *D = new typeof(C); you can use typeid [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Corey Murtagh Guest Posted: Fri Jun 27, 2003 2:11 pm    Post subject: Re: can this be done in C? (a = new B, where B is an instanc Chandra Shekhar Kumar wrote: Quote: shape *D = new typeof(C); you can use typeid Although the OP can indeed use typeid, there is no way that it will help with the problem at hand. The typeid keyword returns a type_info const& which is NOT the type. There is no simple way to create an instance of a class from the type_info for that class. Please, if you're going to give advice, don't waste everyone's time by making it *BAD* advice. -- Corey Murtagh The Electric Monk "Quidquid latine dictum sit, altum viditur!" [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Francis Glassborow Guest Posted: Fri Jun 27, 2003 2:12 pm    Post subject: Re: can this be done in C? (a = new B, where B is an instanc In message <3EFA0E81.E9606F36 (AT) oracle (DOT) com>, Chandra Shekhar Kumar <chandra.kumar (AT) oracle (DOT) com> writes Quote: shape *D = new typeof(C); you can use typeid Please demonstrate how you would use typeid to solve this problem. -- ACCU Spring Conference 2003 April 2-5 The Conference you should not have missed ACCU Spring Conference 2004 Late April Francis Glassborow ACCU [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Siemel Naran Guest Posted: Fri Jun 27, 2003 6:09 pm    Post subject: Re: can this be done in C? (a = new B, where B is an instanc "Chandra Shekhar Kumar" <chandra.kumar (AT) oracle (DOT) com> wrote in message Quote: shape *D = new typeof(C); you can use typeid No. -- +++++++++++ Siemel Naran [ 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: Mon Jun 30, 2003 10:35 am    Post subject: Re: can this be done in C? (a = new B, where B is an instanc Francis Glassborow <francis.glassborow (AT) ntlworld (DOT) com> wrote Quote: In message <3EFA0E81.E9606F36 (AT) oracle (DOT) com>, Chandra Shekhar Kumar [email]chandra.kumar (AT) oracle (DOT) com[/email]> writes shape *D = new typeof(C); you can use typeid Please demonstrate how you would use typeid to solve this problem. if ( typeid( C ) == typeid( square ) ) { D = new square( static_cast< square& >( C ) ) ; } else if ( typeid( C ) == typeid( circle ) ) { D = new circle( static_cast< circle& >( C ) ) ; } else // ... Not recommended, but it can be done. Somewhat more flexible would be to use a std::map< std::type_info, Factory >, or something along those lines, with each derived class registering a factory. In practice, however, I've never found a case where this was interesting. If you have an actual object that you want to duplicate, the clone method is far better, and if you don't, where do you get the type_info from -- you can't read it from a disk, or send it over the network. If you need this, you have to define your own type identification. -- James Kanze GABI Software mailto:kanze (AT) gabi-soft (DOT) fr Conseils en informatique orientée objet/ http://www.gabi-soft.fr Beratung in objektorientierter Datenverarbeitung 11 rue de Rambouillet, 78460 Chevreuse, France, Tél. : +33 (0)1 30 23 45 16 [ 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.