template problem: local variable as non-type argument

I know the reason for the problem. Template instanziation happens at compile
time.
So it cannot handle function parameter of createInstance function at
runtime.

The question is: how shall I realize it differently as follows [pseudo
code]:
     if(i == 1)
         return C<1>();
     if(i == 2)
         return C<2>();
     // ... maintenance nightmare ...

#include <iostream>
class Base {
public:
     virtual void foo() = 0;
};

template<int T>
class C : public Base {
public:
     virtual void foo() { /* default does nothing */ }
};

template<>
class C<1> : public Base {
public:
     virtual void foo() { std::cout << "C<1>::foo "; }
};

template<>
class C<2> : public Base {
public:
     virtual void foo() { std::cout << "C<2>::foo "; }
};

class Factory {
public:
     static Base& createInstance(int i);
};

Base& Factory::createInstance(int i) {
     // PROBLEM:
     // error C2971: 'C' : template parameter 'T' : 'i' : a local variable
cannot be used as
     // a non-type argument
     // WORKS: int const val = 0;
     return C<i>(); //ignore warning: returning address of local variable or
temporary
}

void main() {
     Base& anInstance = Factory::createInstance(1);
     Base& anotherInstance = Factory::createInstance(2);
}

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