Subscribe to events using reflection

·When you use reflection to load and run assemblies, you cannot use language features like the C# += operator or the Visual Basic AddHandler statement to hook up events. This MSDN document (http://msdn.microsoft.com/en-us/library/ms228976.aspx) shows how to link an existing method to an event by getting all the necessary types through reflection and how to create a dynamic method using reflection emit and link it to an event.

A sample:

   1:          // Load an assembly, for example using the Assembly.Load

   2:          // method. In this case, the executing assembly is loaded, to

   3:          // keep the demonstration simple.

   4:          //

   5:          Assembly assem = Assembly.GetExecutingAssembly();

   6:   

   7:          // Get the type that is to be loaded, and create an instance 

   8:          // of it. Activator.CreateInstance has other overloads, if

   9:          // the type lacks a default constructor. The new instance

  10:          // is stored as type Object, to maintain the fiction that 

  11:          // nothing is known about the assembly. (Note that you can

  12:          // get the types in an assembly without knowing their names

  13:          // in advance.)

  14:          //

  15:          Type tExForm = assem.GetType("ExampleForm");

  16:          Object exFormAsObj = Activator.CreateInstance(tExForm);

  17:   

  18:          // Get an EventInfo representing the Click event, and get the

  19:          // type of delegate that handles the event.

  20:          //

  21:          EventInfo evClick = tExForm.GetEvent("Click");

  22:          Type tDelegate = evClick.EventHandlerType;

  23:   

  24:          // If you already have a method with the correct signature,

  25:          // you can simply get a MethodInfo for it. 

  26:          //

  27:          MethodInfo miHandler = 

  28:              typeof(Example).GetMethod("LuckyHandler", 

  29:                  BindingFlags.NonPublic | BindingFlags.Instance);

  30:              

  31:          // Create an instance of the delegate. Using the overloads

  32:          // of CreateDelegate that take MethodInfo is recommended.

  33:          //

  34:          Delegate d = Delegate.CreateDelegate(tDelegate, this, miHandler);

  35:   

  36:          // Get the "add" accessor of the event and invoke it late-

  37:          // bound, passing in the delegate instance. This is equivalent

  38:          // to using the += operator in C#, or AddHandler in Visual

  39:          // Basic. The instance on which the "add" accessor is invoked

  40:          // is the form; the arguments must be passed as an array.

  41:          //

  42:          MethodInfo addHandler = evClick.GetAddMethod();

  43:          Object[] addHandlerArgs = { d };

  44:          addHandler.Invoke(exFormAsObj, addHandlerArgs);

Some related links:

• Using Reflection to link to event with custom handler (http://social.msdn.microsoft.com/forums/en/netfxbcl/thread/c083a0fd-9338-4f92-b6d4-4109096bfc5f/)
• c# reflection: problem subscribing to event(http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/d7f184f1-0964-412a-8659-6759a0e2db83/)
• Raising an event via reflection(http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/44b0d573-5c53-47b0-8e85-6056cbae95b0)
• Event Handling using Reflection(http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/1ead5b74-3d2f-41e0-b699-1f35e16305ec/)