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    <p>Actually, there's no sense to <code>override</code> these values. Actually, the advantages of override is that you can call a method of a derived class without knowing the derived class itself.</p> <p>For example :</p> <pre><code>static void Main() { NaturalFood food = GetSomeFood(); // At this point, we don't know the actual type food.SomeMethodInBaseClass(); // ok } static NaturalFood GetSomeFood() { if(somecondition) { return new Fruits(); } else{ return new Vegetables(); } } public abstract class NaturalFood { public abstract void SomeMethodInBaseClass(); } public class Fruits : NaturalFood { public override void SomeMethodInBaseClass(){ Console.WriteLine("I'm a fruit"); } } public class Vegetables : NaturalFood { public override void SomeMethodInBaseClass(){ Console.WriteLine("I'm a vegetable"); } } </code></pre> <p>No imagine what you wanted to do. In the main method, try to call the AllList :</p> <pre><code>static void Main() { NaturalFood food = GetSomeFood(); // At this point, we don't know the actual type food.SomeMethodInBaseClass(); // ok food.AllList.XXXX; // What? it won't compile } </code></pre> <p>This won't compile. The compiler has no way to know the actual derived class to infer the available enumeration values.</p> <p>However, if you remove the enumeration from the base type, this will works :</p> <pre><code>static void Main() { NaturalFood food = GetSomeFood(); // At this point, we don't know the actual type food.SomeMethodInBaseClass(); // ok Fruits f = new Fruits(); Console.WriteLine( f.AllList.Apple); // Ok Vegetable v = new Vegetable (); Console.WriteLine( v.AllList.Potatoe); // Ok } </code></pre> <p>But as you can see, you have to know explicitly the actual type, and thus, make the polymorphic useless.</p> <p><strong>[Edit]</strong> It's hard to answer to your second edit. Actually there are many many ways to validate such constraint. Without more context it may be difficult to answer. The most simple way I think, is to add to each derived class a overriden property that describe what kind of enumeration is accepted.</p> <pre><code>public enum NaturalFoodType { Unknown = 0, Apple= 1, Banana = 2, Potatoe = 3, Cucumber = 4 } public abstract class NaturalFood { public abstract void SomeMethodInBaseClass(); public abstract IEnumerable&lt;NaturalFoodType&gt; AcceptedFoodType { get; } public bool IsValid(NaturalFoodType type){ return AcceptedFootType.Contains(type); } } public class Fruits : NaturalFood { public override void SomeMethodInBaseClass(){ Console.WriteLine("I'm a fruit"); } public override NaturalFoodType { get { yield return NaturalFoodType.Apple; yield return NaturalFoodType.Banana; } } } public class Vegetables : NaturalFood { public override void SomeMethodInBaseClass(){ Console.WriteLine("I'm a vegetable"); } public override NaturalFoodType { get { yield return NaturalFoodType.Potatoe; yield return NaturalFoodType.Cucumber; } } } </code></pre> <p>But honestly, it start to add a lot of plumbing code, that become quite unreadable. You should consider the problem at a higher scope to find an acceptable solution.</p>
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    1. POHow to enforce derived class to override an enumeration from the base class?
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    1. USSteve B
    1. USSteve B
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    1. COThank you for the example. Makes sense. I have now tried to describe my requirement in more concise terms in "edit2" above.
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    2. COlook at my edit
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