C#: Getting maximum and minimum values of arbitrary properties of all items in a list

Question

I have a specialized list that holds items of type IThing:

public class ThingList : IList
{...}

public interface IThing
{
    Decimal         


        

Answer 1

Here's an attempt, using C# 2.0, at Skilwz's idea.

public delegate T GetPropertyValueDelegate<T>(IThing t);

public T GetMaximum<T>(GetPropertyValueDelegate<T> getter)
    where T : IComparable
{
    if (this.Count == 0) return default(T);

    T max = getter(this[0]);
    for (int i = 1; i < this.Count; i++)
    {
        T ti = getter(this[i]);
        if (max.CompareTo(ti) < 0) max = ti;
    }
    return max;
}

You'd use it like this:

ThingList list;
Decimal maxWeight = list.GetMaximum(delegate(IThing t) { return t.Weight; });

Answer 2

Conclusion: There is no better way for .Net 2.0 (with Visual Studio 2005).

You seem to have misunderstood the answers (especially Jon's). You can use option 3 from his answer. If you don't want to use LinqBridge you can still use a delegate and implement the Max method yourself, similar to the method I've posted:

delegate Decimal PropertyValue(IThing thing);

public class ThingList : IList<IThing> {
    public Decimal Max(PropertyValue prop) {
        Decimal result = Decimal.MinValue;
        foreach (IThing thing in this) {
            result = Math.Max(result, prop(thing));
        }
        return result;
    }
}

Usage:

ThingList lst;
lst.Max(delegate(IThing thing) { return thing.Age; });