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PODetermining a Type of an Object
 

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    <p>Again, I really hope this isn't a matter of opinion; I'm trying to know which is the best way to determine the type of an object that belongs to a certain hierarchy in C#. I have two ways to design my application:</p> <p><strong>1 - Use a property on the base class:</strong></p> <pre><code>public abstract class Parent { public abstract TypeOfObject TypeOfObject { get; } } public class Child1 : Parent { public override TypeOfObject TypeOfObject { get { return TypeOfObject.Child1 } } // ... } public class Child2 : Parent { public override TypeOfObject TypeOfObject { get { return TypeOfObject.Child2 } } // ... } public enum TypeOfObject { Child1, Child2 } public static void Main() { Parent p = new Child1(); switch (p.TypeOfObject) { case TypeOfObject.Child1: _doSomethingWithChild1(p);break; case TypeOfObject.Child2: _doSomethingWithChild2(p);break; } } </code></pre> <p><strong>2 - Use the is operator</strong></p> <pre><code>public abstract class Parent { // ... } public class Child1 { // ... } public class Child2 : Parent { // ... } public enum TypeOfObject { Child1, Child2 } public static void Main() { Parent p = new Child1(); if (p is Child1) _doSomethingWithChild1(p); if (p is Child2) _doSomethingWithChild2(p); } </code></pre> <p>What are the implications of each alternative? I think 2 has a greater performance hit since it relies on metadata, but 1 seems way less elegant. Besides, I learned to do this the 1 way in C++... I'm not sure it's necessary to do so with C#.</p> <p><strong>EDIT 1:</strong></p> <p>I've added the <em>override</em> keyword to the code above. </p> <p><strong>EDIT 2:</strong></p> <p>I'm sorry, I've probably not made myself clear. I will illustrate it better: </p> <p><strong>For example</strong>, I have a WPF <code>Panel</code> object that has a <code>Children</code> property, which returns me <code>UIElement</code>s. I need to know what type a certain element is to act upon it... in my particular case, the user is drawing a graph on the screen, so I need to know how many nodes and how many connections are drawn in order to store then at the database. I can't, unfortunately, use polymorphism for that, right? How will I know if I should add a line to my nodes table or to my connections table?</p>
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    1. COThis is a common OO design mistake. You don't need this. Please read up on "polymorphism" and then close the question.
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    2. COThere are many examples of the first way in the .NET Framework, e.g., XmlDocument/XmlElement/..., XDocument/XElement/..., LambdaExpression/UnaryExpression/...
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    3. CO@S.Lott: +1 :) (blah)
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