"Andy Little" wrote
"Tobias Schwinger" wrote
// IS_TYPE((int))::value is true // IS_TYPE((1))::value is false
Does anyone know how to implement this without a typeof operator?
I havent got a solution but one avenue thats seems to be in the right field is to exploit the difference between a function call and a declaration:
Sometype func_or_value( Entity_to_test);
eg assume Entity_to_test is a type then func_or_value is a function, else func_or_value is a variable.
The following seems to work in VC7.1 though it declares a variable if T is a value: ------------- #include <boost/preprocessor/cat.hpp> #include <boost/typeof/typeof.hpp> #include <boost/type_traits/remove_pointer.hpp> #include <boost/type_traits/is_function.hpp> #include <iostream> // necessary for the return/decl type of VARIABLE_OR_TYPE(T) struct SomeType{ // SomeType must have a unconstrained value ctor template <typename T> SomeType( T const &){}; }; #define VARIABLE_OR_TYPE(T) \ SomeType BOOST_PP_CAT(var_or_func,T)(T); // test VARIABLE_OR_TYPE(int); VARIABLE_OR_TYPE(1); int main() { // these would need to be wrapped in the macro I guess... // var_or_funcint is the decl from VARIABLE_OR_TYPE(int); typedef BOOST_TYPEOF(&var_or_funcint) tt; std::cout << boost::is_function<boost::remove_pointer<tt>::type >::value <<'\n'; // var_or_func1 is the decl from VARIABLE_OR_TYPE(1); typedef BOOST_TYPEOF(&var_or_func1) t1; std::cout << boost::is_function<boost::remove_pointer<t1>::type >::value <<'\n'; } regards Andy Little