C#: How to add an attributes to an object at run-time?

Question

As an entity class, I want to add an attributes at run-time, how should I do?

Answer 1

Edit: please clarify, are you talking about c# attributes or members on your class?

The only way you can add c# attributes is to generate a completely new class with the additional attributes, compile and load the new assembly to your existing AppDomain.