equalitywtf.cs

    public class Cat
        : IEquatable<Cat>
    {
        public readonly string Name;
        public readonly int Age;

        public Cat(string name, int age)
        {
            Name = name;
            Age = age;
        }

        public bool Equals(Cat other)
        {
            if (ReferenceEquals(null, other))
                return false;
            if (ReferenceEquals(this, other))
                return true;
            return string.Equals(Name, other.Name) && Age == other.Age;
        }

        public override bool Equals(object obj)
        {
            if (ReferenceEquals(null, obj))
                return false;
            if (ReferenceEquals(this, obj))
                return true;
            if (obj.GetType() != this.GetType())
                return false;
            return Equals((Cat)obj);
        }

        public override int GetHashCode()
        {
            unchecked
            {
                return ((Name != null ? Name.GetHashCode() : 0) * 397) ^ Age;
            }
        }

        public static bool operator ==(Cat left, Cat right)
        {
            return Equals(left, right);
        }

        public static bool operator !=(Cat left, Cat right)
        {
            return !Equals(left, right);
        }
    }