Question

Consider I have a some Factory class:

class Factory
{
 public:
 Factory();
 virtual ~Factory();

 /*
  some factory methods
 */
}

All of the methods create objects according to a string given as a parameter. But one of these methods creates objects that depends on template parameter like:

template <typename Tp>
some_class<Tp>* fac_meth(string str);

The actual type will be decided at runtime.
Is it possible to do such a thing?

Answer 1

In one word: no.

In more words: at compile time all the instantiations of that function template will occur (i.e. the compiler will determine all the different instances of that function that is needed for different types [e.g. some_type<int*>, some_type<double*> etc.])

Consider run-time polymorphism (i.e. an inheritance hierarchy) for something like this.