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POHow can I create delegates to a property of unknown type?
 

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  1. POHow can I create delegates to a property of unknown type?
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    <p>I'm using reflection to access an object's properties by name, to call the get method. This is a relatively slow operation over thousands of iterations, even when I cache the PropertyInfo for each property. I'm trying to come up with something faster using delegates, but VB.Net won't allow me to call CreateDelegate on an object without knowing the return type of the property at compile time. How can I do this?</p> <ul> <li>I access properties via their (string) name</li> <li>The return type of the property is unknown at compile time</li> <li>I'm trying to create a delegate to quickly access one or more properties on thousands of instances of an object</li> </ul> <p>Edit: Code follows</p> <p>testC is an example object which contains the properties I'm acessing by name. del is the delegate I want to use to call the property on an instance of testC.</p> <pre><code>Public Class testC Public Property prop1 As String Public Property prop2 As Double Public Property prop3 As Integer Public Property prop4 As String Public Property prop5 As String Public Property prop6 As String End Class Public Delegate Function del() As Object </code></pre> <p>The first time I access each property, I use reflection to get the property from it's name, and attempt to build a delegate to quickly access it on other instances of the object in the future.</p> <pre><code>Dim pi As Reflection.PropertyInfo = obj.GetType().GetProperty(propName) Dim myDelegate As Object = System.Delegate.CreateDelegate(GetType(del), pi.GetGetMethod()) </code></pre> <p>Calling CreateDelegate throws this exception:</p> <blockquote> <p>System.ArgumentException: Cannot bind to the target method because its signature or security transparency is not compatible with that of the delegate type.</p> </blockquote>
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    1. USTrent
    1. USTrent
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      1. POHow can I create delegates to a property of unknown type?
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    1. COI'm not sure what benefit Delegates would provide. Wouldn't the delegate still need to use reflection to get the PropertyInfo and the objects underlying value?
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      1. POHow can I create delegates to a property of unknown type?
      1. USWilliam
    2. COThe first time it accesses the property it will, but the delegate will access the same property on a large number of instances of the object
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      1. POHow can I create delegates to a property of unknown type?
      1. USTrent
    3. COCan you use a generic return type (like Object)?
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      1. POHow can I create delegates to a property of unknown type?
      1. USDouglas Barbin
 

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