`std::variant` (Manual Virtual Dispatch, Using `std::visit`)¶

Overview ¶

Much like std::variant (Manual Virtual Dispatch, Using if)
Only using std::visit()
… with manually defined visitor methods
⟶ Adding another sensor type requires another operator()

Virtual Access ¶

code/variant-manual-visit/virtual.h¶

#pragma once

struct get_temperature_visitor
{
    double operator()(Sensor1& s) { return s.get_temperature(); }
    double operator()(Sensor2& s) { return s.get_temperature(); }
    // <--- take care to implement operator() for all types covered in union
};

static inline double get_temperature(Sensor& s)
{
    return std::visit(get_temperature_visitor(), s);
}