Thread: member function or global?

This is an old question to which I don't remember the answer. A quick few searches didn't clarify. Suppose I have the option of building functionality into an object or having it done to the object. I recall the latter being preferable in this type of circumstance, and std::string being made a negative example. Why?

Code:

//minimal container of a 2-dimensional array, or whatever.
template<class T>
class grid
{
  public:
      enum print_mode { text, binary }
      grid(unsigned w, unsigned h);
      T & operator()(unsigned x, unsigned y);
      const T & operator()(unsigned x, unsigned y) const;
      const unsigned width() const;
      const unsigned height() const;
      //should it be:
      void print_to_file(const std::string & path, print_mode m);
      ~grid();
  protected:
      //whatever
};

//or should it be:
template<class T>
void print_to_file(const & grid<T> g, const std::string & path, grid<T>::print_mode m);

//I suppose the second method would move enum print_mode outside of grid, too.

You have a function that opens a device and constructs an apparently design specific representation. If this function can be created as a non-member, non-friend function, it should be created as a non-member, non-friend function.

Instead of focusing on a few methods that provide a complete interface, the class has methods that do nothing more than provide an "ease of use" interface.

Thanks.