Algorithms as member or non-member functions?

Question

I have a simple data structure, a triangular matrix indexed by k and l , where l runs from 1 to N and k runs from 1 to l :

template<int N> class triangular_matrix {
    std::vector<int> elem;
public:
    int& operator()(int k, int l) {
        return elem[(N * (N + 1) - l * (l + 1)) / 2 + k - 1];
    }
};

I also have several algorithms operating on this data structure. All of them access triangular_matrix only via operator() .

What are the pros and cons of making these algorithms member functions of triangular_matrix instead of making them non-member functions (in a non-global namespace)?

Answer 1

In C++ it's common to put everything that doesn't have to be a member function in a non-member function. Herb Sutter wrote a nice article about it a while back.