June 15, 2003 template argument deduction | ||||
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#include <stdio.h> template <class T> void f(void(T::*)(void)) // Error: 'T' must be a class name preceding '::' { printf("1\n"); } template <class T> void f(...) { printf("2\n"); } struct A { }; int main() { f<A>(0); f<int>(0); return 0; } See 14.8.2 Template argument deduction [temp.deduct], paragraph 2: "... If a substitution in a template parameter or in the function type of the function template results in an invalid type, type deduction fails. ..." and 14.8.3 Overload resolution [temp.over]: "... If, for a given function template, argument deduction fails, no such function is added to the set of candidate functions for that template. ..." Extracted from Boost's type_traits library. bye, Christof -- http://cmeerw.org JID: cmeerw@jabber.at mailto cmeerw at web.de ...and what have you contributed to the Net? |
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