C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  What's the difference betwwen explicit instantiaion and expl          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Andy Guest Posted: Sun Jan 30, 2005 9:34 am    Post subject: What's the difference betwwen explicit instantiaion and expl Hi, I got a little confused on 'instantiation' and 'specialization', espcially for explicit instantiation and explicit sepcialization. Can anybody explain the difference? Thanks a lot! Andy Back to top Andy Guest Posted: Sun Jan 30, 2005 9:40 am    Post subject: Re: What's the difference betwwen explicit instantiaion and Is an instantiation a process of producing a specialization? Thanks, andy Back to top Alf P. Steinbach Guest Posted: Sun Jan 30, 2005 9:49 am    Post subject: Re: What's the difference betwwen explicit instantiaion and * Andy: Quote: I got a little confused on 'instantiation' and 'specialization', espcially for explicit instantiation and explicit sepcialization. Can anybody explain the difference? You specialize a template when you provide a definition for some actual template parameter, e.g., saying "in general, use the general definition, but for template parameter T=int, use this more specialized definition". This specialized definition may or may not be actually used, so specialization by itself does not cause a more thorough analyzis than the original template definition. You instantiate a template when you cause the compiler to generate code for the template. This requires all template parameters given actual parameters, and it causes full-blown analysis of this specialization of the template. For example, you declare an object of the template type, or you call a templated function. At that point the template definition is expanded to actual, ordinary C++ code (the template instance), which is subject to the usual C++ compilation (OK, some rules, e.g. about multiple definitions, are slightly different). You can also instantiate a template without using it, via special syntax. -- A: Because it messes up the order in which people normally read text. Q: Why is it such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail? Back to top Shezan Baig Guest Posted: Sun Jan 30, 2005 4:27 pm    Post subject: Re: What's the difference betwwen explicit instantiaion and Andy wrote: Quote: Hi, I got a little confused on 'instantiation' and 'specialization', espcially for explicit instantiation and explicit sepcialization. Can anybody explain the difference? Thanks a lot! Andy If I have a templated class: template <typename FOO> class Bar { ... }; I explicitly *instantiate* Bar<char> like this: template <> class Bar<char>; Notice that the implementation of Bar<char> does not change (i.e., it is not specialised). When I *specialise* Bar<char>, I do this: template <> class Bar<char> { ... }; Now, Bar<char> has a new meaning (i.e., the template class 'Bar' now does something "special" when used with 'char' as the template argument). Hope this helps, -shez- Back to top Max M. Guest Posted: Sun Jan 30, 2005 4:36 pm    Post subject: Re: What's the difference betwwen explicit instantiaion and Shezan Baig wrote: Quote: I explicitly *instantiate* Bar<char> like this: template <> class Bar<char>; The correct syntax for explicit instantiation is template class Bar<char>; (with no '<>'.) MM Back to top Shezan Baig Guest Posted: Sun Jan 30, 2005 11:46 pm    Post subject: Re: What's the difference betwwen explicit instantiaion and Max M. wrote: Quote: Shezan Baig wrote: I explicitly *instantiate* Bar<char> like this: template <> class Bar<char>; The correct syntax for explicit instantiation is template class Bar<char>; (with no '<>'.) MM Yes, this is correct. My bad. -shez- 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 (comp.lang.c++) 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.