Class Templates

Does This Work With Classes?

class point
{
public:
    point(int x, int y);
    int x() const;
    int y() const;
private:
    int _x;
    int _y;
};

What about other data types?

• point with int

• point with float

• …

Example: point as a Class Template (1)

template <typename T>
class point
{
public:
    point(T x, T y) : _x(x), _y(y) {}
    T x() const;
    T y() const;
private:
    T _x;
    T _y;
};

Example: point as a Class Template (2)

template <typename T>  // method template parameter
T                      // method return type
point<T>::x() const    // class template parameter
{
    return _x;
}

Pooh …

Last Words

• Template classes must be defined in the header file

• Compiler instantiates code

• Linker recognizes duplicates ⟶ unifies

• Rules are very complicated

• ⟶ Language in the language

• Compiler error message often very confusing