Question

I want to instantiate a template class with data types that are available at runtime in variables. For example, consider this class:

template <typename T, unsigned int U>
class Allocator
{
public:
    T * pointer;
    Allocator() { pointer = new T[U]; }
    ~Allocator() { delete [] pointer; }
};

Now I want to use it like this:

int main()
{
    string temp = "int";
    unsigned int count = 64;
    Allocator<temp, count> a;
    return 0;
}

Is there any way of doing this?

I am facing this problem in the context of serializing derived classes with base pointers. I use RTTI to identify the real type of derived class, but the information of the real type is stored in a string. My problem is to be able to dynamic_cast to the type (available as a string at runtime) from the base pointer. Please help.

Answer 1

You can’t. Data types must be known at compile time. Maybe using Boost or unions may solve the problem in a non-pretty way.

Good luck!