C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  ambiguous or not?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message catcher Guest Posted: Tue Jun 24, 2003 7:34 pm    Post subject: ambiguous or not? template<typename T> void fun(T x) {}; void fun(int x) {}; int main() { fun<int>(3); } This code is ambiguous or not? What the standard says about it? Back to top Victor Bazarov Guest Posted: Tue Jun 24, 2003 7:51 pm    Post subject: Re: ambiguous or not? "catcher" <wangxin99 (AT) hotmail (DOT) com> wrote... Quote: template<typename T void fun(T x) {}; Please lose the semicolon Quote: void fun(int x) {}; Please lose the semicolon Quote: int main() { fun } This code is ambiguous or not? What the standard says about it? No, it is not ambiguous. The template function instantiated for 'T == int' should be used. And even if you drop the <int> thing after the name, it's still unambiguous -- the regular function should be used. See Clause 14, subs 14.2 and 14.8.3 along with 13.3.3... Victor Back to top catcher Guest Posted: Thu Jun 26, 2003 2:50 pm    Post subject: Re: ambiguous or not? I checked the standard, It says that the common function has higher priority than template function, when ambiguity happens. so fun(3) will call a common function. But I cant understand why fun<int>(3) should call a template function. I cant find the item about it in the standard. In fact, I compiled these codes using Intel C++, and the result is insteresting: fun<int>(3) call a common function, not a template function. Back to top Victor Bazarov Guest Posted: Thu Jun 26, 2003 3:41 pm    Post subject: Re: ambiguous or not? "catcher" <wangxin99 (AT) hotmail (DOT) com> wrote... Quote: I checked the standard, It says that the common function has higher priority than template function, when ambiguity happens. so fun(3) will call a common function. But I cant understand why fun<int>(3) should call a template function. I cant find the item about it in the standard. In fact, I compiled these codes using Intel C++, and the result is insteresting: fun<int>(3) call a common function, not a template function. It is quite possible that I'm not reading it correctly. Asking in comp.std.c++ is advised. I understand it that if the template argument list is specified, then non-template functions are not added to the set of candidate functions. However, 14.8.3/1 has the following sentence: "The complete set of candidate functions includes all the function templates instantiated in this way and all of the non-template overloaded functions of the same name" which may be interpreted that only the NAME ('fun' in your case) is going to be considered for identification purposes. However, after further search I found 14.3/7, which says, "When the template in a template-id is an overloaded function template, both non-template functions in the overload set and function templates in the overload set for which the template-arguments do not match the template-parameters are ignored. If none of the function templates have matching template-parameters, the program is ill-formed." [To help understand, "template-id" is formed by an identifier followed by an optionally empty set of angle brackets, as in "fun<int>"] That seems pretty straight-forward to me. 'fun<int>' should force the compiler to ignore 'fun' or 'fun<double>' or whatever else is out there. Victor Back to top        C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1 Powered by phpBB © 2001, 2006 phpBB Group