But when you need to use IEqualityComparer, it's not possibile to use a lambda predicate.
The Interface needs a class, then you have to create a new type that inherit from IEqualityComparer.
You can use this workaround:
public class EqualityComparer<T> : IEqualityComparer<T> { private Func<T, T, bool> _fnEquals; private Func<T, int> _fnGetHashCode;
public EqualityComparer(Func<T, T, bool> fnEquals, Func<T, int> fnGetHashCode) { _fnEquals = fnEquals; _fnGetHashCode = fnGetHashCode; }
public bool Equals(T x, T y) { return _fnEquals(x, y); }
public int GetHashCode(T obj) { return _fnGetHashCode(obj); } }
The simple usage is:
Dictionary<int, string> d = new Dictionary<int, string>() { { 1, "a" }, { 2, "a" }, { 3, "b" } }; var d2 = d.Distinct(new EqualityComparer<KeyValuePair<int, string>>((kvp1, kvp2) => kvp1.Value == kvp2.Value, kvp => kvp.Value.GetHashCode()));
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