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    <p>Write-only properties are a rare beast, and don't exist in the System.ComponentModel / PropertyDescriptor space. <code>PropertyDescriptor</code>s are designed to be readable. I could probably hack <code>HyperDescriptor</code> to shim write-only properties, but it would be a hack - and it would presumably have to throw exceptions for <code>get</code>, which could impact calling code quite a bit.</p> <p>As an aside; I generally advise <em>against</em> write-only properties; the text-book example that people trot out is passwords (<code>public string Password {private get;set;}</code>) - I'd much rather have a <code>void SetPassword(string newPassword)</code> method...</p> <p>What is it that you actually want to do? There are a range of options here, all very achievable:</p> <ul> <li>use reflection alone (slow; maybe not an option)</li> <li>use <code>Delegate.CreateDelegate</code> (very easy)</li> <li>use <code>Expression.Compile</code> (a <em>little</em> harder, but not much)</li> <li>use <code>Reflection.Emit</code> (quite hard)</li> <li>shim write-only properties into <code>PropertyDescriptor</code> (quite hard)</li> </ul> <p>If you let me know what you actually want to do (rather than the way you are currently trying to do it), I might be able to help more.</p> <p>As an example using <code>Delegate.CreateDelegate</code> (note you would want to stash the delegate somewhere and re-use it lots of times):</p> <p><strong>edited to show how to do it if you don't know the specific types at runtime</strong></p> <pre><code>using System; using System.Reflection; class Foo { public string Bar { private get; set; } public override string ToString() { return Bar; // to prove working } } static class Program { static void Main() { ISetter setter = Setter.Create(typeof(Foo), "Bar"); Foo foo = new Foo(); setter.SetValue(foo, "abc"); string s = foo.ToString(); // prove working } } public interface ISetter { void SetValue(object target, object value); } public static class Setter { public static ISetter Create(Type type, string propertyName) { if (type == null) throw new ArgumentNullException("type"); if (propertyName == null) throw new ArgumentNullException("propertyName"); return Create(type.GetProperty(propertyName)); } public static ISetter Create(PropertyInfo property) { if(property == null) throw new ArgumentNullException("property"); if (!property.CanWrite) throw new InvalidOperationException("Property cannot be written"); Type type = typeof(TypedSetter&lt;,&gt;).MakeGenericType( property.ReflectedType, property.PropertyType); return (ISetter) Activator.CreateInstance( type, property.GetSetMethod()); } } public class TypedSetter&lt;TTarget, TValue&gt; : ISetter { private readonly Action&lt;TTarget, TValue&gt; setter; public TypedSetter(MethodInfo method) { setter = (Action&lt;TTarget, TValue&gt;)Delegate.CreateDelegate( typeof(Action&lt;TTarget, TValue&gt;), method); } void ISetter.SetValue(object target, object value) { setter((TTarget)target, (TValue)value); } public void SetValue(TTarget target, TValue value) { setter(target, value); } } </code></pre> <hr> <p>Or alternatively using the <code>Expression</code> API (.NET 3.5):</p> <pre><code>using System; using System.Linq.Expressions; using System.Reflection; class Foo { public string Bar { private get; set; } public override string ToString() { return Bar; // to prove working } } static class Program { static void Main() { Action&lt;object,object&gt; setter = Setter.Create(typeof(Foo), "Bar"); Foo foo = new Foo(); setter(foo, "abc"); string s = foo.ToString(); } } public static class Setter { public static Action&lt;object,object&gt; Create(Type type, string propertyName) { if (type == null) throw new ArgumentNullException("type"); if (propertyName == null) throw new ArgumentNullException("propertyName"); return Create(type.GetProperty(propertyName)); } public static Action&lt;object,object&gt; Create(PropertyInfo property) { if(property == null) throw new ArgumentNullException("property"); if (!property.CanWrite) throw new InvalidOperationException("Property cannot be written"); var objParam = Expression.Parameter(typeof(object), "obj"); var valueParam = Expression.Parameter(typeof(object), "value"); var body = Expression.Call( Expression.Convert(objParam, property.ReflectedType), property.GetSetMethod(), Expression.Convert(valueParam, property.PropertyType)); return Expression.Lambda&lt;Action&lt;object, object&gt;&gt;( body, objParam, valueParam).Compile(); } } </code></pre>
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    1. COHi Marc, thank you very much for your prompt reply! The setters works as a proxy to configure some view elements in a webforms application. A presenter will via a view interface set the required configuration on the view - it uses reflection over the interface and the view implementation to end up using SetValue to set the config on the view. As our systems grows, and there are a lot of views (nested inside each other), the reflection part is being really slow.
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    2. COI think your delegate-solution seems like the right approach for me - I have the logic for the SetValue hidden away in a general class. I'll go try it out immediately. Are there any more documentation/"getting started writeups" about any of the other possibilities that you would recommend?
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    3. COI've just looked a little closer at it. One problem with the delegate solution, is that I do not know the type of the view implementation (your Foo) at compile time, only the interface which Foo implements. At run time I have the type. Then I should use reflection to create the delegate - I don't know if that'll ruin performance then...
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