The gist of the problem is that the following template does not compile without the "using namespace std" statement:
template <class T> struct MapZipHelperImpl { typedef typename boost::tuple< const T&, const T& > iter_value_type;
void operator()( const iter_value_type& iter_value ) { using namespace std; // without this the next line does not compile! typename T::first_type val = iter_value.get<0>().first ; } };
The error is:
error: expected primary-expression before ‘)’ token
The code is incorrect. For me, it doesn't compile even with the "using namespace std". The correct code is: typename T::first_type val = iter_value.template get<0>().first ; Note the added "template" keyword. Older versions of GCC may have been lenient accepting code like this without the "template" keyword, but it has always been incorrect. Regards, Nate