C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Differentiate between a template class and class template Goto page 1, 2  Next          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message james Guest Posted: Thu Oct 14, 2004 10:02 pm    Post subject: Differentiate between a template class and class template Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? Thanks, james [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Alberto Barbati Guest Posted: Fri Oct 15, 2004 11:30 am    Post subject: Re: Differentiate between a template class and class templat james wrote: Quote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? According to Vandevoorde/Josuttis (C++ Templates, chapter 7): <quote> * [The term /class template/] is a parametrized description of a family of classes. * The term /template class/ on the other hand has been used for: - a synonym for class template - to refer to classes generated from templates - to refer to classes with a name that is a template-id [...] Because of this imprecision, we avoid the term /template class/ in this book. </quote> I cannot but agree with them and it would be good if people stopped using the term template class once and for all. In support to this view, the C++ Standard has undergone with TC1 a thorough revision to replace all uses of the term template class with class template wherever applicable. Alberto [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Thierry Miceli Guest Posted: Fri Oct 15, 2004 4:10 pm    Post subject: Re: Differentiate between a template class and class templat Quote: I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? You'll find the answer here: http://www.comeaucomputing.com/techtalk/templates/#terms Regards, Thierry www.ideat-solutions.com [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top L.Suresh Guest Posted: Fri Oct 15, 2004 4:10 pm    Post subject: Re: Differentiate between a template class and class templat class template - Is actually a template that is a class. Here Foo is a class template. template <typename T> class Foo { }; template class - Is actually a class that is instantiated from a template. Foo<int> f; Here f has a type Foo<int>, which is a template class. You can think think that the second word is qualified with first word. "class template" : It is a template. template for what? template for class.. "template class" : It is a class. Is it ordinary class? It is a class generated fro a template. The same thing exists for funtcion template and template function. HTH --lsu Quote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? Thanks, james [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Terje Slettebø Guest Posted: Fri Oct 15, 2004 11:11 pm    Post subject: Re: Differentiate between a template class and class templat "Alberto Barbati" <AlbertoBarbati (AT) libero (DOT) it> wrote Quote: james wrote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? According to Vandevoorde/Josuttis (C++ Templates, chapter 7): <snip> This reminds me of the "new operator" vs "operator new" confusion, but at least in that case, they both have a well-defined meaning. Regards, Terje [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Antoun Kanawati Guest Posted: Sat Oct 16, 2004 10:16 am    Post subject: Re: Differentiate between a template class and class templat L.Suresh wrote: Quote: class template - Is actually a template that is a class. Here Foo is a class template. template <typename T class Foo { }; template class - Is actually a class that is instantiated from a template. Foo Here f has a type Foo<int>, which is a template class. You can think think that the second word is qualified with first word. "class template" : It is a template. template for what? template for class.. "template class" : It is a class. Is it ordinary class? It is a class generated fro a template. The same thing exists for funtcion template and template function. I like to think of templates and their instantiations. This sort of terminology is just confusing. It may make sense in a hightly formalized context to create such distinctions (e.g.: standards document). However, as soon as such lingo makes it out into the wild, the meanings get fuzzy. Basically, we're saying that the phrase 'A B' means that we're referring to a B, which may be quite obvious if you're Commander Data communicating with the computer. In any case, these constructs are not robust; the inversion of sequences, against convention, is an instrument literary, if you know what I mean. But, seriously, technical terminology needs to be robust, and resistant to syntactic variatoin. A lot of technical documentation is done by writing experts, whose primary concern is with form, not substance. <digress> Specialization is a highly prized quality in current culture. While this leads to great advances in various domains, it also creates vast chasms between them. We often fail to educate our engineers and scientists in communication and language skills. We also fail to educate our 'business' specialists in the domains that they're going to do business in, etc... </digress> So, a robust technical term is one that dictates its correct form, even in the absence of substance. More reasonably: if you have a set of transformations representing common errors, and you apply them to the technical term, ideally all of them should be detectable as errors on the basis of form alone. Practically, you don't want the erroneous forms to express a different concept that fits equally well where your intended concept is supposed to be; i.e.: even if the syntax and grammar were correct, you'd expect that in the general context of the technical domain, and without prior knowledge of the intended meaning, a reader will be able to detect that something is wrong; ideally, this reader should also be able to deduce the original meaning. For example, if a Scheme programmer looks at sentence where 'class template' is used erroneously instead of 'template class', can this programmer detect, reliably and without prior knowledge of the intended meaning, that the sentence is wrong? -- A. Kanawati [email]NO.antounk.SPAM (AT) comcast (DOT) net[/email] [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Tom Widmer Guest Posted: Sat Oct 16, 2004 4:58 pm    Post subject: Re: Differentiate between a template class and class templat On Thu, 14 Oct 2004 22:02:39 +0000 (UTC), [email]james_merch (AT) hotmail (DOT) com[/email] (james) wrote: Quote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? A template class is generally an informal name for what the C++ standard calls a class template. IOW, they are the same thing. However, "template class" is misleading, since it leads to the impression that a class template is actually a class, whereas in fact it is a template for making classes. However, since "template class" isn't a formally defined term, they might be using it to refer to a class template specialization, but I don't think that's the most common usage. Although the standard doesn't use "template class" at all, it does use the phrase "non-template class", but, to be honest, I think that's not really a correct usage - by definition, a class isn't a class template in any case, so "non-template class" == "class". Tom [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Francis Glassborow Guest Posted: Sat Oct 16, 2004 4:58 pm    Post subject: Re: Differentiate between a template class and class templat In article <e2ef22db.0410131551.1c43209e (AT) posting (DOT) google.com>, james <james_merch (AT) hotmail (DOT) com> writes Quote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? A template class is a template from which class definitions can be generated (just as a function template is a template from which functions can be generated.) {Moderator's note: I'm pretty sure Francis meant the next sentence to begin with "A class template..." -mod/dk} A template class is whatever you make it mean. Personally I do not use the term, but if I did it would be to refer to a class that had been generated from a template. -- Francis Glassborow ACCU Author of 'You Can Do It!' see http://www.spellen.org/youcandoit For project ideas and contributions: http://www.spellen.org/youcandoit/projects [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Sumit Rajan Guest Posted: Sat Oct 16, 2004 4:58 pm    Post subject: Re: Differentiate between a template class and class templat james wrote: Quote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? In case of you have access to a copy of "C++ Templates: The Complete Guide" you may like to look up Section 7.1("Class Template" or "Template Class"?). -- Sumit Rajan <sumit DOT rajan AT gmail DOT com> [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Sharad Kala Guest Posted: Sat Oct 16, 2004 4:58 pm    Post subject: Re: Differentiate between a template class and class templat "james" <james_merch (AT) hotmail (DOT) com> wrote in message Quote: I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? Is there anything like "template class" ? AFAIK, no. The correct term to be used is "class template". But the irony is that while writing a class template you write "template class" template <class MyType> :-) Sharad [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Graeme Prentice Guest Posted: Sat Oct 16, 2004 4:58 pm    Post subject: Re: Differentiate between a template class and class templat On Thu, 14 Oct 2004 22:02:39 +0000 (UTC), james wrote: Quote: Hi guys, I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? "class template" refers to the definition of a class that is a template. A class template is a template - it's a "pattern" e.g. template <typename T> class abc { T x; }; abc is the name of a template - a class template. It is not a class. abc<int> is the name of a class, it is not a template but is a class generated from a template - a class generated from a template is sometimes referred to as a template class. A class generated from a template has an official name of "class template specialization". abc<int> is also called a template-id i.e. a template-id is the name of a template followed by a list of one or more template arguments between the angle brackets. A template-id identifies a specialization of a template. In my opinion this is a semi trick question. If you search on groups.google.com you'll get 12,600 hits for "class template" and 72,800 for "template class" - however the "template class" search picks up template template, you get equal numbers and you can soon see that the terms are used interchangeably. The 2003 revision of the C++ standard (TC1) uses the term "class template" 475 times and "template class" about 4 or 5 times. The 1998 C++ standard uses "template class" approx 215 times and "class template" 255 times. i.e. the 2003 revision of the C++ standard changed many instances of "template class" to "class template". Similarly some instances "template function" were changed to "function template". If you have a copy of C++ templates by Vandevoord and Josuttis, they point out that "template class" is used to mean at least three different things - as a synonym for class template - to refer to classes generated from templates - to refer to classes with a name that is a template-id The book says it avoids the term "template class" because of the multiple meanings - however in every day usage, it's usually clear what is meant when "template class" is used. In the C++ standard, the correct terminology can matter quite a lot (especially regarding functions) but in every day usage the meaning of "template class" is usually clear from the context. Graeme [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Keith H Duggar Guest Posted: Sun Oct 17, 2004 1:37 am    Post subject: Re: Differentiate between a template class and class templat Quote: I like to think of templates and their instantiations. This sort of terminology is just confusing. As evidenced by the OP and the info Alberto provided. Quote: It may make sense in a hightly formalized context to create such distinctions (e.g.: standards document). You are right it does make sense to create distintions; but (as you point out later) not using confusing terminology. Quote: digress Specialization is a highly prized quality in current culture. While this leads to great advances in various domains, it also creates vast chasms between them. We often fail to educate our engineers and scientists in communication and language skills. We also fail to educate our 'business' specialists in the domains that they're going to do business in, etc... /digress That is certainly true. Quote: For example, if a Scheme programmer looks at sentence where 'class template' is used erroneously instead of 'template class', can this programmer detect, reliably and without prior knowledge of the intended meaning, that the sentence is wrong? As evidenced by the OP often even C++ programmers can't detect the error. So often writers forget that the chief purpose of human language is to COMMUNICATE with fellow humans. Not to create some form of *machine* language that is difficult to understand. <digress> For similar reasons, in another thread, I once objected to the use of cryptic, trendy acronyms like IMHO, IIRC, FWIW, etc. rather than simply writing (or better eliminating) the useless phrase. This notion received very little support. Many seemed habitually attached to their specialized internet language. Then, just a few days ago, there was a prime time news report about how children are using multitudes of new cryptic acronyms to hide the meaning of their conversations from parents often leading them into harm (like to Michael or Pee Wee's house). </digress> [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Gabriel Dos Reis Guest Posted: Mon Oct 18, 2004 1:40 pm    Post subject: Re: Differentiate between a template class and class templat Sharad Kala <no_spam.sharadk_ind (AT) yahoo (DOT) com> writes: Quote: "james" <james_merch (AT) hotmail (DOT) com> wrote in message I had an interview a few days ago and the interviewer asked me this C++ question: "Differentiate between a template class and class template?" Can anyone explain me the differences? Is there anything like "template class" ? AFAIK, no. The correct term to be used is "class template". That term was used in the earlier drafts of the C++ standard text. It has been changed (I think) between CD2 and the final draft. It used to mean a class generated from a class template. It can lead to interesting sentences :-) -- Gabriel Dos Reis [email]gdr (AT) cs (DOT) tamu.edu[/email] Texas A&M University -- Computer Science Department 301, Bright Building -- College Station, TX 77843-3112 [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Graeme Prentice Guest Posted: Mon Oct 18, 2004 1:40 pm    Post subject: Re: Differentiate between a template class and class templat On Sat, 16 Oct 2004 16:58:03 +0000 (UTC), Graeme Prentice wrote: Quote: If you have a copy of C++ templates by Vandevoord and Josuttis, they point out that "template class" is used to mean at least three different things - as a synonym for class template - to refer to classes generated from templates - to refer to classes with a name that is a template-id The book says it avoids the term "template class" because of the multiple meanings - however in every day usage, it's usually clear what is meant when "template class" is used. oops, I didn't quite mean that - the book doesn't say both of those things in the last sentence above. The book says it avoids the term "template class" because of its imprecision. The second part of the above is my opinion. Graeme [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Terje Slettebø Guest Posted: Mon Oct 18, 2004 4:31 pm    Post subject: Re: Differentiate between a template class and class templat "Keith H Duggar" <duggar (AT) alum (DOT) mit.edu> wrote Quote: I like to think of templates and their instantiations. This sort of terminology is just confusing. digress For similar reasons, in another thread, I once objected to the use of cryptic, trendy acronyms like IMHO, IIRC, FWIW, etc. rather than simply writing (or better eliminating) the useless phrase. This notion received very little support. Many seemed habitually attached to their specialized internet language. Then, just a few days ago, there was a prime time news report about how children are using multitudes of new cryptic acronyms to hide the meaning of their conversations from parents often leading them into harm (like to Michael or Pee Wee's house). /digress Children using a special language/secret codes/slang is nothing new. It lets them have something that is "theirs"; their own way of expression. As for acronyms and terminology, as has been pointed out in previous discussions about that, those are very common in virtually every field: They enable concise communication and avoiding ambiguity. Think about it: Would you rather talk about Complementary Metal-Oxide Semiconductor Random Access Memory, or CMOS RAM? Similarly, online communication has developed its own "language" of common terminology and abbreviations. This post by James Dennett, from the earlier discussion, I think gives a very good account of the points: http://www.google.com/groups?selm=D0FKc.22362%249I.13304%40okepread02 Regards, Terje [ 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 Goto page 1, 2  Next Page 1 of 2   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.