| James Lothian <jameslothian1@gmail.com>: Mar 23 11:22PM Given the following code: template <int L, int M> class Unit {}; template <class U1, class U2> struct Mul {}; template <int... L, int... R> struct Mul<Unit<L...>, Unit<R...> > { typedef Unit<L + R...> Result; }; typedef Unit<1, 0> Length; typedef Unit<0, 1> Mass; // Error here typedef typename Mul<Length, Mass>::Result LM; int main() { LM lm; return 0; } Visual Studio 2019 and 2015 both say: C:\Users\James\Documents\SpecTest\SpecTest.cpp(21,37): error C2039: 'Result': is not a member of 'Mul<Length,Mass>' C:\Users\James\Documents\SpecTest\SpecTest.cpp(21): message : see declaration of 'Mul<Length,Mass>' Apparently, VC++ picks the base case of the template rather than the specialisation. Every online c++ compiler I've managed to find (presumably using gcc) accepts this code. So, who's right? Am I doing something stupid here? Thanks, James |
| Juha Nieminen <nospam@thanks.invalid>: Mar 23 06:44AM >> Sure, it's longer, but a lot easier to read and understand at a >> quick glance. > I always select the std::/chrono::-namespaces in my .cpp-file globally. I don't see any advantage in writing "seconds(123)" instead of "std::chrono::seconds(123)". The latter makes it absolutely clear and unambiguous what it is. The former is confusing, especially for someone who is just casually reading the code for the first time. I am not the kind of coder who has this strange obsession with making everything as short as possible. I prefer clarity over brevity. Overt brevity only introduces obfuscation. |
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