Question

I’m trying to write two template functions. They must simply return reference to local variable. But it doesn’t work:

class Cube_cache_value {
public:
  //...
  template<>
  QVector<unsigned short>& get_buffer<unsigned short>() { return vector; } // error here

  template<>
  QVector<float>& get_buffer<float>() { return float_vector; }

private:
  QVector<unsigned short> vector;
  QVector<float> float_vector;
};

error: explicit specialization in non-namespace scope ‘class hsp::Cube_cache_value’

Then I’ve tried to get functions out of class scope, but compiler still don’t like it:

class Cube_cache_value {
public:
  //...
  inline QVector<unsigned short>& get_buffer() { return vector; }
  inline QVector<float>& get_float_buffer() { return float_vector; }

private:
  QVector<unsigned short> vector;
  QVector<float> float_vector;
};

template<>
QVector<unsigned short>& get_buffer<unsigned short>(Cube_cache_value* v) { //error here
  return v->get_buffer();
}

template<>
QVector<float>& get_buffer<float>(Cube_cache_value* v) { return v->get_float_buffer(); }

error: expected initializer before ‘<‘ token

Please correct my code.

Answer 1

It looks like bad design in the first place. Why is your class storing 2 distinct vectors for 2 possible types? It’s a bloat and you’d need to do this for any other type you might want.

Why not do this ?

template <typename T>
class Cube_cache_value {
public:
  // ...
  QVector<T>& get_buffer() { return buf; } 

private:
  QVector<T> buf;
};