Dot.net: AOP with PostSharp - Property accessor modified

Question:

How can I change a property getter for all my properties by using AOP?
How to use PostSharp, an Aspect Oriented Programming framework, to intercept property getter calls.


Answer:
Here I will show a simple setup that I use with PostSharp. (free community version)

I just want to modify the result string of some of my Properties by annotating them with a custom attribute.

You can always use other popular AOP frameworks (Castle Windsor, Spring.NET, Microsoft Unity etc.) as alternatives to PostSharp.

In order to intercept property getter calls,

Follow these steps:

1. Download the latest version of PostSharp
2. Add the PostSharp reference to your project.
3. Create an Aspect (custom attribute to intercept a call)
   

   using System;
   using PostSharp.Aspects;
   
   namespace AOPSample
   {
       [Serializable]
       [AttributeUsage(AttributeTargets.Property)]
       public sealed class LocalizationAttribute : LocationInterceptionAspect
       {
           // Invoked at runtime whenever someone gets the value of the field or property.
           public override void OnGetValue(LocationInterceptionArgs args)
           {
               if (LocalizationHelper.MustLocalize && LocalizationHelper.LocalizationIsOn)
               {
                   base.OnGetValue(args);
   
                   // do something with your string, I add some fake localization
                   string s = args.Value as string;
                   s = s + "_en-GB";
                   args.Value = s;
               }
               else
               {
                   base.OnGetValue(args);
               }
           }
   
   
       }
   }
   
   

   
   
4. Annotate the properties with your new aspect attribute where you want to intercept calls.
   

   ...
      [LocalizationAttribute]
      public virtual string Name { get; set; }
    ...
   

Now, each time the property is called your OnGetValue interception method is called.