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POHow do I specify LINQ's OrderBy direction as a boolean?
 

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  1. POHow do I specify LINQ's OrderBy direction as a boolean?
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    <p>I have a simple data class that has this signature:</p> <pre><code>internal interface IMyClass { string Letter { get; } int Number { get; } } </code></pre> <p>I wish to be able to sort this data based on a field (specified as <code>string sortField</code>) and a direction (specified as <code>bool isAscending</code>)</p> <p>Currently I am using a <code>switch</code> (with the ascending logic within each case as <code>if</code>)</p> <pre><code>IEnumerable&lt;IMyClass&gt; lst = new IMyClass[];//provided as paramater switch (sortField) { case "letter": if( isAscending ) { lst = lst.OrderBy( s =&gt; s.Letter ); } else { lst = lst.OrderByDescending( s =&gt; s.Letter ); } break; case "number": if( isAscending ) { lst = lst.OrderBy( s =&gt; s.Number ); } else { lst = lst.OrderByDescending( s =&gt; s.Number ); } break; } </code></pre> <p>This is pretty ugly, for 2 properties, but when the sort logic differs it becomes a problem (we also see <code>s =&gt; s.Number</code> is duplicated twice in the code)</p> <p><strong>Question</strong> What is the best way to pass a boolean to choose the sort direction?</p> <p><strong>What I've Tried</strong> I've ripped apart System.Core.dll and found the OrderBy Extension method implementations:</p> <p>OrderBy:</p> <pre><code>public static IOrderedEnumerable&lt;TSource&gt; OrderBy&lt;TSource, TKey&gt;( this IEnumerable&lt;TSource&gt; source, Func&lt;TSource, TKey&gt; keySelector ){ return new OrderedEnumerable&lt;TSource, TKey&gt;( source, keySelector, null, false ); } </code></pre> <p>OrderByDescending:</p> <pre><code>public static IOrderedEnumerable&lt;TSource&gt; OrderByDescending&lt;TSource, TKey&gt;( this IEnumerable&lt;TSource&gt; source, Func&lt;TSource, TKey&gt; keySelector ){ return new OrderedEnumerable&lt;TSource, TKey&gt;( source, keySelector, null, true ); } </code></pre> <p>It appears the purpose of having 2 named methods is to abstract this boolean away. I can't create my own extension easily as <code>OrderedEnumberable</code> is internal to System.Core, and writing a layer to go from bool -> methodName -> bool seems wrong to me.</p>
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