Friend template specialization

Asked May 13 '20 at 06:28

Active May 13 '20 at 06:46

Viewed 40 times

I want to make in-class friend function definition to keep my API consistent in single place. I can't understand how to make that piece of code work and why it doesn't work now
All I want is to create a free function specialization inside a class and keep access to private members

template<class T, class R = T>
R lerp(T a, T b, double t) {
    return (1.0 - t) * a + b * t;
}

class Vec {
    double x, y;
public:
    Vec(double x, double y) : x(x), y(y) {}

    template<>
    friend Vec lerp<const Vec&, Vec>(const Vec& a, const Vec& b, double t) {
        return Vec(lerp(a.x, b.x, t), lerp(a.y, b.y, t), t);
    }
};

I searched for similar questions and had found it quite hard to understand

edited May 13 '20 at 06:46

asked May 13 '20 at 06:28

IC_

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Why not just overload? – Jarod42 May 13 '20 at 06:39
@Jarod42 how do i access private members then? – IC_ May 13 '20 at 06:42
I meant `friend Vec lerp(const Vec& a, const Vec&b, double t) {/*..*/}`. – Jarod42 May 13 '20 at 06:50
isn't it specialization itself? What differences? – IC_ May 13 '20 at 06:53
1

it isn't a template (specialization). More reading about [template-specialization-vs-function-overloading](https://stackoverflow.com/questions/7108033/template-specialization-vs-function-overloading). – Jarod42 May 13 '20 at 07:01
You need a separate declaration and definition: https://godbolt.org/z/2s4i4A – Alan Birtles May 13 '20 at 07:10

Friend template specialization

0 Answers0