[RESOLVED] template partial specialization

[jakevdp]

Hello,
I am trying to implement a dense and sparse matrix class using template specialization. The first two class method definitions work (one with no specialization, one with full specialization), but the third definition with partial specialization does not: if the commented region is uncommented, the example fails to compile.

#include <iostream>
using std::cout;

enum MatrixType{DENSE,SPARSE};

template<class T,MatrixType MT>
struct Matrix{ Matrix(); };

template<class T, MatrixType MT>
Matrix<T,MT>::Matrix<T,MT>(){
  cout << "default constructor\n";
}

template<>
Matrix<double,DENSE>::Matrix<double,DENSE>(){
  cout << "<double,DENSE> constructor\n";
}
/*
template<class T>
Matrix<T,DENSE>::Matrix<T,DENSE>(){
  cout << "<T,DENSE> constructor\n";
}
*/
int main(){
  Matrix<double,SPARSE> V1;
  Matrix<int,DENSE> V2;
  Matrix<double,DENSE> V3;
  return 0;
}

One fix is to do full specializations of all needed types, but this requires a lot of code duplication. I suspect that this has to do with Matrix<T,DENSE> not being recognized as a valid class. Any ideas how to efficiently implement this, or something structurally similar?