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POCan you create a simple 'EqualityComparer<T>' using a lambda expression
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  1. POCan you create a simple 'EqualityComparer<T>' using a lambda expression
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    copied!<p>IMPORTANT: THIS IS <strong>NOT A LINQ-TO-SQL</strong> QUESTION. This is LINQ to objects.</p> <p><strong>Short question:</strong> </p> <p>Is there a simple way in LINQ to objects to get a distinct list of objects from a list based on a key property on the objects.</p> <p><strong>Long question:</strong></p> <p>I am trying to do a <a href="http://www.hookedonlinq.com/DistinctOperator.ashx" rel="noreferrer"><code>Distinct()</code></a> operation on a list of <strong>objects</strong> that have a key as one of their properties.</p> <pre><code>class GalleryImage { public int Key { get;set; } public string Caption { get;set; } public string Filename { get; set; } public string[] Tags {g et; set; } } </code></pre> <p>I have a list of <code>Gallery</code> objects that contain <code>GalleryImage[]</code>.</p> <p>Because of the way the webservice works [sic] I have duplicates of the <code>GalleryImage</code> object. i thought it would be a simple matter to use <code>Distinct()</code> to get a distinct list.</p> <p>This is the LINQ query I want to use :</p> <pre><code>var allImages = Galleries.SelectMany(x =&gt; x.Images); var distinctImages = allImages.Distinct&lt;GalleryImage&gt;(new EqualityComparer&lt;GalleryImage&gt;((a, b) =&gt; a.id == b.id)); </code></pre> <p>The problem is that <code>EqualityComparer</code> is an abstract class.</p> <p>I dont want to :</p> <ul> <li>implement IEquatable on <code>GalleryImage</code> because it is generated</li> <li>have to write a separate class to implement <code>IEqualityComparer</code> as <a href="http://www.hookedonlinq.com/DistinctOperator.ashx" rel="noreferrer">shown here</a></li> </ul> <p>Is there a concrete implementation of <code>EqualityComparer</code> somewhere that I'm missing?</p> <p>I would have thought there would be an easy way to get 'distinct' objects from a set based on a key.</p>
 

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