// cs0617,cs : 'MyNamedArg' is not a valid named attribute argument. Named attribute arguments must be fields which are not readonly, static or const, or properties with a set accessor which are not static. // Line : 20 using System; [AttributeUsage (AttributeTargets.Class, AllowMultiple = true)] public class SimpleAttribute : Attribute { string name = null; public readonly string MyNamedArg; public SimpleAttribute (string name) { this.name = name; } } [Simple ("Dummy", MyNamedArg = "Dude!")] public class Blah { public static void Main () { } }