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POCan an enum return a new instance in C#?
 

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  1. POCan an enum return a new instance in C#?
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    <p>Greetings everyone!</p> <p>I'll try to make my problem simple: I have an <code>enum</code> to select which <code>ObjType</code> I should use (<code>ObjTypeA</code> and <code>ObjTypeB</code> both inherits from <code>ObjType</code>). So I created a method to extend the given <code>enum</code>, in order to return a new instance according to the selected property in the <code>enum</code>, like follows in the code. I think it works more or less like a factory design pattern. So far so good, but eventually, like in the class <code>MyClass</code>, I may attempt to create <code>n</code> instances of <code>ObjTypeA</code> or <code>ObjTypeB</code>, but I'll have to face the <code>if</code> statement everytime I call the <code>GetObjTypeInstance()</code> method. So:</p> <ul> <li>Can an <code>enum</code> return an instance, something like: <code>public enum EObjType { ObjTypeA = new ObjTypeA(), ObjTypeB = new ObjTypeB() }</code>? Actually, it'd be better to append some <code>GetInstance()</code> method to the <code>ObjTypeA</code> and to the <code>ObjTypeB</code> options in the <code>enum</code>. If there's a way to do this, how can I do it? Doing this I'd avoid those if statements every while step.</li> <li>Is there any other (and better) way to this this (if you understood my problem...)? How?</li> </ul> <p>Thanks in advance!</p> <p>Follow the example code:</p> <pre><code>public static class EObjTypeExt { public static ObjType GetObjTypeInstance(this EObjType ot) { if (ot == EObjType.ObjTypeA) { return new ObjTypeA(); } else if (ot == EObjType.ObjTypeB) { return new ObjTypeB(); } throw new ArgumentOutOfRangeException("unrecognized type!"); } } public enum EObjType { ObjTypeA, ObjTypeB } public class MyClass { ObjType[] obj { get; set; } public MyClass(EObjType otEnum, int n) { this.obj = new ObjType[n]; int i = 0; while (i &lt; n) { this.obj[i] = otEnum.GetObjTypeInstance(); i++; } } } </code></pre>
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    1. COWhy do you want to avoid the if-statements in the sample code?
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    2. COIf `n` is big enough (and it generally is in my problem), then the code would become very slow.
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    3. COYou mean the `if (ot == EObjType.ObjTypeA)` checks? They won't be significant at all next to the object allocations.
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