how to get value of known field from within generic object in a list c#-CodePudding

Im trying to write a generic function that receives an instance of a type "Location" and a list of objects - where each one of the objects has a field of this "location" type how do I get the value of each one of the "locations" in the list? theres more to thecode but this is the only relevant part

public static T SmallestDistance<T>(this Location current, List<T> toFindIn)
        {
            double minDis = double.MaxValue;
            foreach(T cur in toFindIn )
            {
                Location temp = typeof(T).GetProperty(typeof(Location).Name).GetValue(cur);
            }
            
        }

CodePudding user response：

To get a Location, first, you need to ensure that all items in toFindIn list have the property. You could add an interface to ensure that, then you could use a generic type constraint.

public class Location
{
    /// ...
}

public interface ILocationHolder
{
    Location Location { get; }
}

public static class ExtensionsClass
{
    public static T SmallestDistance<T>(this Location current, List<T> toFindIn) where T : ILocationHolder
    {
        var minDis = double.MaxValue;
        foreach (var cur in toFindIn)
        {
            var temp = cur.Location;
        }

        //...
    }
}

CodePudding user response：

One way is to use an interface:

interface IHasLocation
{
    Location Location { get; }
}

Then constrain T:

public static T SmallestDistance<T>(this Location current, List<T> toFindIn)
where T : IHasLocation
{
    double minDis = double.MaxValue;
    foreach (T cur in toFindIn)
    {
        Location temp = cur.Location;
    
    //...
}

Or if you can't do that, you can pass a function:

public static T SmallestDistance<T>(
    this Location current,
    List<T> toFindIn,
    Func<T, Location> getLocation)
{
    double minDis = double.MaxValue;
    foreach (T cur in toFindIn)
    {
        Location temp = getLocation(cur);
    
    //...
}

Which can be called like this:

class SomethingWithALocation
{
    public Location Location { get; }
}

var list = new List<SomethingWithALocation>();
var something = someLocation.SmallestDistance(list, item => item.Location);