C#•2y ago

❔ Question about abstraction

public interface ILocatable
{
    public double Longitude { get; set; }
    public double Latitude { get; set; }
    
    public double DistanceTo(double longitude, double latitude)
    {
        const double R = 6371; // Earth radius in kilometers

        double dLat = (latitude - Latitude) * Math.PI / 180;
        double dLon = (longitude - Longitude) * Math.PI / 180;
        double lat1 = Latitude * Math.PI / 180;
        double lat2 = latitude * Math.PI / 180;

        double a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
                   Math.Sin(dLon / 2) * Math.Sin(dLon / 2) * Math.Cos(lat1) * Math.Cos(lat2);
        double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));

        return R * c;
    }
}

public interface ILocatable
{
    public double Longitude { get; set; }
    public double Latitude { get; set; }
    
    public double DistanceTo(double longitude, double latitude)
    {
        const double R = 6371; // Earth radius in kilometers

        double dLat = (latitude - Latitude) * Math.PI / 180;
        double dLon = (longitude - Longitude) * Math.PI / 180;
        double lat1 = Latitude * Math.PI / 180;
        double lat2 = latitude * Math.PI / 180;

        double a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
                   Math.Sin(dLon / 2) * Math.Sin(dLon / 2) * Math.Cos(lat1) * Math.Cos(lat2);
        double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));

        return R * c;
    }
}

Is this a correct usage of interfaces? then having

public class Center : BaseEntity, ILocatable

public class Center : BaseEntity, ILocatable

implement an abstract class an and interface

10 Replies

barcodeOP•2y ago

or should the method not be implemented and then implement in class extending it?

Mideks•2y ago

Interface with method implementations? 🤯

cap5lut•2y ago

interfaces describe contracts -> behavior of something, so it fits. base classes and alike are implementation details, which seems to fit here as well. with this little piece of code w/o further context it seems fine iirc default interface method implementations were added in c# 8.0

Mideks•2y ago

I think this is an anti-pattern for most use cases.

cap5lut•2y ago

i think its a totally fitting use case here

barcodeOP•2y ago

the other option is copying the code in 5 places

cap5lut•2y ago

as long as the actual ILocatable type isnt volumetric that method is accurate

Sossenbinder•2y ago

I usually view default interface implementations as "mixins", I don't use them a lot, but there are good use cases since the alternative is either duplication or often using an abstract class which in turn causes issues if your class already inherits from another one

cap5lut•2y ago

tbh i think this is a really good example for the usage of default interface implementations 😂

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Question about abstraction