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    <p>I got inspired by this question to try and find out how this kind of deep null checking can be done with an easier / prettier syntax using expression trees. While I do agree with the answers stating that it <em>might</em> be a bad design if you often need to access instances deep in the hierarchy, I also do think that in some cases, such as data presentation, it can be very useful. </p> <p>So I created an extension method, that will allow you to write:</p> <pre><code>var berries = cake.IfNotNull(c =&gt; c.Frosting.Berries); </code></pre> <p>This will return the Berries if no part of the expression is null. If null is encountered, null is returned. There are some caveats though, in the current version it will only work with simple member access, and it only works on .NET Framework 4, because it uses the MemberExpression.Update method, which is new in v4. This is the code for the IfNotNull extension method:</p> <pre><code>using System; using System.Collections.Generic; using System.Linq.Expressions; namespace dr.IfNotNullOperator.PoC { public static class ObjectExtensions { public static TResult IfNotNull&lt;TArg,TResult&gt;(this TArg arg, Expression&lt;Func&lt;TArg,TResult&gt;&gt; expression) { if (expression == null) throw new ArgumentNullException("expression"); if (ReferenceEquals(arg, null)) return default(TResult); var stack = new Stack&lt;MemberExpression&gt;(); var expr = expression.Body as MemberExpression; while(expr != null) { stack.Push(expr); expr = expr.Expression as MemberExpression; } if (stack.Count == 0 || !(stack.Peek().Expression is ParameterExpression)) throw new ApplicationException(String.Format("The expression '{0}' contains unsupported constructs.", expression)); object a = arg; while(stack.Count &gt; 0) { expr = stack.Pop(); var p = expr.Expression as ParameterExpression; if (p == null) { p = Expression.Parameter(a.GetType(), "x"); expr = expr.Update(p); } var lambda = Expression.Lambda(expr, p); Delegate t = lambda.Compile(); a = t.DynamicInvoke(a); if (ReferenceEquals(a, null)) return default(TResult); } return (TResult)a; } } } </code></pre> <p>It works by examining the expression tree representing your expression, and evaluating the parts one after the other; each time checking that the result is not null. </p> <p>I am sure this could be extended so that other expressions than MemberExpression is supported. Consider this as proof-of-concept code, and please keep in mind that there will be a performance penalty by using it (which will probably not matter in many cases, but don't use it in a tight loop :-) )</p>
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    1. PODeep null checking, is there a better way?
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    1. COI'm impressed by your lambda skills :) the syntax does however seem to be a tad bit more complex than one would like, atleast for the if-statement scenario
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    2. COCool, but it runs like 100x more code than an if..&&. It's only worthwhile if it still compiles down to an if..&&.
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    3. CO@Kurian, of course it depends on your requirements :-)
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