Tutorial :Do auto-implemented properties support attributes?


I was told that in c# attributes are not allowed on the auto-implemented properties. Is that true? if so why?

EDIT: I got this information from a popular book on LINQ and could not believe it! EDIT: Refer page 34 of LINQ Unleashed by Paul Kimmel where he says "Attributes are not allowed on auto-implemented properties, so roll your own if you need an attribute"


The easiest way to prove that's wrong is to just test it:

using System;  using System.ComponentModel;  using System.Reflection;    class Test  {      [Description("Auto-implemented property")]      public static string Foo { get; set; }          static void Main(string[] args)      {          var property = typeof(Test).GetProperty("Foo");          var attributes = property.GetCustomAttributes                  (typeof(DescriptionAttribute), false);            foreach (DescriptionAttribute description in attributes)          {              Console.WriteLine(description.Description);          }      }  }  

I suggest you email the author so he can publish it as an erratum. If he meant that you can't apply an attribute to the field, this will give him a chance to explain more carefully.


You can apply attributes to automatic properties without a problem.

Quote from MSDN:

Attributes are permitted on auto-implemented properties but obviously not on the backing fields since those are not accessible from your source code. If you must use an attribute on the backing field of a property, just create a regular property.


I think that author meant, that you can't apply custom attributes to private backing field. For example, if you want to mark automatic property as non serialized, you can't do this:

[Serializable]  public class MyClass  {      [field:NonSerializedAttribute()]      public int Id      {          get;          private set;      }  }  

This code compiles, but it doesn’t work. You can apply attribute to property itself, but you can't apply it for backing field.


Note also that any Automatic property will have the CompilerGeneratedAttribute applied to it as well.

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