On Mon, 2007-03-26 at 21:39 +0200, Seweryn Habdank-Wojewódzki wrote:
Hi!
Douglas Gregor wrote:
template < typename T, typename U > void test ( boost::function<T(U)> & f ); [snip] boost::function<int (void)> h = &f3; boost::function<void (void)> i = &f4;
The problem is that "int(void)" is just an alternative spelling for "int()", i.e., a function type for a function that takes no parameters but returns an "int". A function type int() cannot match a template parameter T(U), because there is nothing to match the "U".
Thanks for reply. However still I do not know how to proceed in that case, because functions can not be partially specialized. Is there any opportunity to prepare more less such a function which will automatically detects arguments of boost::function template?
You can write multiple overloads of your "test" function, each of which accepts boost::function instances with a different number of function arguments: template<typename R> void test (boost::function<T(void)>& f); template<typename R, typename T1> void test (boost::function<T(T1)>& f); template<typename R, typename T1, typename T2> void test (boost::function<T(T1, T2)>& f); template<typename R, typename T1, typename T2, typename T3> void test (boost::function<T(T1, T2, T3)>& f); Tedious, unfortunately, but it works. Cheers, Doug