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    <p>Here are two C# solutions, one basically is the same but more neat and is good when you have small number of child classes.</p> <pre><code>public class Parent { } public class Child1 : Parent { } public class Child2 : Parent { } public class Action { private static Dictionary&lt;Type, Action&lt;Parent&gt;&gt; _d = new Dictionary&lt;Type, Action&lt;Parent&gt;&gt;() { {typeof(Child1), p=&gt;action((Child1)p)}, {typeof(Child2), p=&gt;action((Child2)p)}, {typeof(Parent), p=&gt;action(p)} }; public static void perform(Parent p) { _d[p.GetType()](p); } private static void action(Parent p) { } private static void action(Child1 c1) { } private static void action(Child2 c2) { } } class Program { static void Main(string[] args) { Parent p = new Child1(); Action.perform(p); } }`enter code here` </code></pre> <p>Anyhow it breaks OCP but is faster than using reflection. This one does not break OCP but uses reflection to fill the dictionary:</p> <pre><code>public class Action { private static Dictionary&lt;Type, Action&lt;Parent&gt;&gt; _d; static Action() { Initialize(); } private static void Initialize() { var methods = typeof(Action) .GetMethods(BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic) .Where(IsActionMethod) .ToList(); _d = methods.ToDictionary(m =&gt; m.GetParameters().First().ParameterType, m =&gt; (Action&lt;Parent&gt;) (x =&gt; m.Invoke(null, new[] {x}))); } private static bool IsActionMethod(MethodInfo methodInfo) { var parameters = methodInfo.GetParameters(); return parameters.Length == 1 &amp;&amp; typeof(Parent).IsAssignableFrom(parameters.First().ParameterType) &amp;&amp; methodInfo.ReturnType == typeof(void); } public static void perform(Parent p) { _d[p.GetType()](p); } private static void action(Parent p) { } private static void action(Child1 c1) { } private static void action(Child2 c2) { } } </code></pre>
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    1. USYurii Hohan
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    1. COThis is what I'm looking for!! Really thank you!
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    2. COOK, you can accept the answer and upvote
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