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POHow can I get object instance from ()=>foo.Title expression
 

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  1. POHow can I get object instance from ()=>foo.Title expression
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    <p>I have a simple class with a property</p> <pre><code>class Foo { string Title { get; set; } } </code></pre> <p>I am trying to simplify data binding by calling a function like</p> <pre><code>BindToText(titleTextBox, ()=&gt;foo.Title ); </code></pre> <p>which is declared like</p> <pre><code>void BindToText&lt;T&gt;(Control control, Expression&lt;Func&lt;T&gt;&gt; property) { var mex = property.Body as MemberExpression; string name = mex.Member.Name; control.DataBindings.Add("Text", ??? , name); } </code></pre> <p>so what do I put in <code>???</code> for the instance of my <code>Foo</code> class. How do I get a refernce to the calling <code>foo</code> instance from the lambda expression?</p> <p><strong>edit:</strong> The instance should be there somewhere because I can call <code>property.Compile()</code> and create a delegate that uses the <code>foo</code> instance inside my <code>BindToText</code> function. So my question is if this can be done without adding a reference to the instance in the function parameters. I call upon <a href="http://en.wikipedia.org/wiki/Occam&#39;s_razor" rel="nofollow noreferrer">Occum's Razor</a> to yield the simplest solution.</p> <p><strong>edit 2:</strong> What many have failed to notice is the <em>closure</em> that exists in accessing the instance of <code>foo</code> inside my function, if I compile the lambda. How come the compiler knows where to find the instance, and I don't? I insist that there has to be an answer, <em>without</em> having to pass an extra argument.</p> <hr> <h2>Solution</h2> <p>Thanks to <a href="https://stackoverflow.com/users/46594/virtualblackfox">VirtualBlackFox</a> the solution is such:</p> <pre><code>void BindText&lt;T&gt;(TextBoxBase text, Expression&lt;Func&lt;T&gt;&gt; property) { var mex = property.Body as MemberExpression; string name = mex.Member.Name; var fex = mex.Expression as MemberExpression; var cex = fex.Expression as ConstantExpression; var fld = fex.Member as FieldInfo; var x = fld.GetValue(cex.Value); text.DataBindings.Add("Text", x, name); } </code></pre> <p>which alows me to simply type <code>BindText(titleText, () =&gt; foo.Title);</code>.</p>
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