How to handle units in c++ interface

Question

I am currently designing an API where I want that the user to be able to write code like this:

PowerMeter.forceVoltage(1 mV);
PowerMeter.settlingTime(1 ms);
         


        

Answer 1

I prefer the solution from Anders K, however you may use a template to save some time implementing all units as a separte class which can be timeconsuming and prone to errors as you may need to write a lot of code by hand:

enum Unit {
    MILI_VOLT = -3,
    VOLT = 0,
    KILO_VOLT = 3
};

class PowerMeter
{
public:

    template
    void ForceVoltage(double val)
    {
        std::cout << val * pow(10.0, N) << endl;
    };
};

Use like this:

        PowerMeter pm;
        pm.ForceVoltage(1);
        pm.ForceVoltage(1);
        pm.ForceVoltage(1);