Question

Is there a way to have the compile deduce the template parameter automatically?

template<class T>  struct TestA  {     TestA(T v) {}  }; template<class T> void TestB(T v) { } int main() {     TestB (5); } 

Test B works fine, however when i change it to TestA it will not compile with the error ‘ use of class template requires template argument list’

Answer 1

No, there isn’t. Class templates are never deduced. The usual pattern is to have a make_ free function:

template<class T> TestA<T> make_TestA(T v) {     return TestA<T>(v); } 

See std::pair and std::make_pair, for example.

In C++0x you will be able to do

auto someVariable = make_TestA(5); 

to avoid having to specify the type for local variables.