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POCustom ExpressionTree ToString
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  1. POCustom ExpressionTree ToString
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    copied!<p>I am trying to create an ExpressionVisitor in order to recreate the expression as the inputed string (with some exception such that capture variable should be displayed as text).</p> <p>I am stuck when I need to visit expression member of expression member. How can I make the following :</p> <pre><code>public class Starter { private static void Main(string[] args) { var test = new SomeClass(); test.EchoTest(); Console.ReadLine(); } } public class SomeClass { public string StringMember { get; set; } public SomeClass Other { get; set; } public void EchoTest() { var capturedString = "localStringValue"; Echo((() =&gt; "hardcodedString"));//Ok : () =&gt; "hardcodedString" Echo((() =&gt; capturedString));//Ok : () =&gt; "localStringValue" (I want the value in this case) Echo((() =&gt; this.StringMember));//Ok : () =&gt; this.StringMember Echo((() =&gt; this.Other.StringMember));//Failed, expected :() =&gt; this.Other.StringMember , received : () =&gt; this.Other.this.Other } private void Echo(Expression&lt;Func&lt;string&gt;&gt; expression) { Console.WriteLine(PathVisitor.GetPath(expression)); } } public class PathVisitor : ExpressionVisitor { private string _path; protected override Expression VisitLambda&lt;T&gt;(Expression&lt;T&gt; node) { Visit(node.Body); _path = string.Format("() =&gt; {0}", _path); return node; } protected override Expression VisitConstant(ConstantExpression node) { _path = string.Format("\"{0}\"", node.Value); return node; } protected override Expression VisitMember(MemberExpression node) { var generatedClass = null != Attribute.GetCustomAttribute(node.Expression.Type, typeof(CompilerGeneratedAttribute)); if (node.Expression.NodeType == ExpressionType.Constant &amp;&amp; generatedClass) { var getter = Expression.Lambda(node); //let's eval captured Variable _path = string.Format("\"{0}\"", getter.Compile().DynamicInvoke()); } else if (node.Expression.NodeType == ExpressionType.Constant) { _path = string.Format("this.{0}", node.Member.Name); } else { base.Visit(node.Expression); var callerPath = _path; _path = string.Format("{0}.{1}", callerPath, _path); } return node; } public static string GetPath(Expression expression) { var visitor = new PathVisitor(); visitor.Visit(expression); return visitor._path; } } </code></pre>
 

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