Why does my .NET Attribute not perform an action?

Question

I\'ve created a simple Attribute:

[AttributeUsage(AttributeTargets.Method)]
public class InitAttribute : System.Attribute
{
    public InitAttribute()
    {
         


        

Answer 1

The attribute is never actually instantiated and so its constructor is never called. The attribute remains as meta-data until you use reflection to retrieve it. As has been mentioned previously what you are after is an Aspect Oriented Programming tool. PostSharp works by altering the assembly as a post-build step. If you are using the Castle Windsor or Unity Inversion of Control Containers they both offer AOP capabilities as well.

Answer 2

Attributes only allow decoration of types and members, but the attribute itself cannot acces the decorated object. You will have to use the constructor parameters of the attribute to pass in any data you require to work with within the attribute.

If you wish to use attributes to automatically alter the behaviour of their target objects, you will have to look at AOP solutions like PostSharp.

Answer 3

If you need to perform an action as control enters a method, you should look at aspect-oriented programming and frameworks such as PostSharp. Attributes are not designed to perform anything by themselves. They are just a bunch of data (or metadata if you will) attached to stuff in IL assemblies that can be queried at runtime.