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    <p>As others already mentioned, when you want to check for reference equality, bypassing any <code>==</code> or <code>Equals()</code>, use <a href="http://msdn.microsoft.com/en-us/library/system.object.referenceequals" rel="nofollow"><code>object.ReferenceEquals()</code></a>.</p> <p>Also, when overloading <code>==</code>, you should also override <code>Equals()</code> (and implement <code>IEquatable&lt;T&gt;</code>). When you do that, you can then take advantage of the fact that <code>object.Equals(object, object)</code> makes all the null checks and then invokes <code>Equals()</code>. So, your code could look like this:</p> <pre><code>public bool Equals(HalfDay other) { if (object.ReferenceEquals(other, null)) return false; if (object.ReferenceEquals(other, this)) return true; return this.Date.Date == other.Date.Date &amp;&amp; this.Half == other.Half; } public int GetHashCode() { // TODO } public override bool Equals(object other) { return Equals(other as HalfDay); } public static bool operator ==(HalfDay halfday1, HalfDay halfday2) { return object.Equals(halfday1, halfday2); } public static bool operator !=(HalfDay halfday1, HalfDay halfday2) { return !(halfday1 == halfday2); } </code></pre> <p>Also, keep in mind what happens when there is a type that inherits from <code>HalfDay</code>. If you don't want to deal with that, make <code>HalfDay</code> <code>sealed</code>.</p> <p>But, considering that you're also implementing comparison operators, you should considering unifying those too. For an example (with detailed explanation), see <a href="http://ericlippert.com/2013/10/07/math-from-scratch-part-six-comparisons/" rel="nofollow">Eric Lippert's <em>Math from scratch, part six: comparisons</em></a> (you don't need to read the rest of the series).</p>
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    1. POWriting an operator overload in C#, for a complex type, which relies on the operator itself
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    1. COGiven that HalfDay was originally supposed to be a POCO for EF Code First, what effect would implementing IEquatable<T> have on the class? I've tried to use simple data types through my POCOs where possible, but I was getting annoyed with rewriting the same code over and over to compare two HalfDays, hence why I looked into operator overloads. Is it "acceptable" to add these overloads and overrides to POCOs? I appreciate that might not be a black and white answer.
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    2. CO@DanielArkley The way I understand it, [POCO](https://en.wikipedia.org/wiki/Plain_Old_CLR_Object) means “an object that's not tied to your ORM in any way”. It doesn't mean you can't implement interfaces or overload operators on it.
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    3. COFair enough :) Implemented all of that. For GetHashCode, I used: `public int GetHashCode() { return new { Date = Date, Half = Half }.GetHashCode(); }`
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