Hook up a delegate using reflection

hook up a delegate using reflection

How do you hook up a delegate to an event?

To hook up a delegate using reflection Load an assembly that contains a type that raises events. Get a Type object representing the type, and create an instance of the type. Get an EventInfo object representing the event, and use the EventHandlerType property to get the type of delegate used to handle the event.

How to get the type of a delegate in an assembly?

The new instance is stored as type Object to maintain the fiction that nothing is known about the assembly. (Reflection allows you to get the types in an assembly without knowing their names in advance.) Get an EventInfo object representing the event, and use the EventHandlerType property to get the type of delegate used to handle the event.

Why cant I use the += operator when using reflection to load assemblies?

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.

How to add a late-bound event to a delegate?

// Delegate^ d = Delegate::CreateDelegate (tDelegate, this, miHandler); // Get the add accessor of the event and invoke it late- // bound, passing in the delegate instance. This is equivalent // to using the += operator in C#, or AddHandler in Visual // Basic.

How do I hook up an event-handling delegate?

For another way to hook up an event-handling delegate, see the code example for the AddEventHandler method of the EventInfo class. Load an assembly that contains a type that raises events. Assemblies are usually loaded with the Assembly.Load method.

How to get the type of a delegate in an assembly?

The new instance is stored as type Object to maintain the fiction that nothing is known about the assembly. (Reflection allows you to get the types in an assembly without knowing their names in advance.) Get an EventInfo object representing the event, and use the EventHandlerType property to get the type of delegate used to handle the event.

How do I create an instance of a delegate?

Create an instance of the delegate, using the CreateDelegate method. This method is static ( Shared in Visual Basic), so the delegate type must be supplied. Using the overloads of CreateDelegate that take a MethodInfo is recommended.

How do I invoke a delegate from a form?

// Delegate^ dEmitted = handler->CreateDelegate (tDelegate); addHandler->Invoke (exFormAsObj, gcnew array { dEmitted }); // Show the form. Clicking on the form causes the two // delegates to be invoked.

Are delegates static or dynamic binding?

Comapred to early or static binding, Delegates could qualify as Dynamic Binding. Delegates are the backbone behind Events, wich are propably the most common example of Late/Dynamic Binding you can find in programming. All Events do is wrap a Delegate into add and remove accessors.

Should I choose between delegates or events?

The choice of delegates or events is often difficult, because the two language features are similar. Events are even built using the language support for delegates. They both offer a late binding scenario: they enable scenarios where a component communicates by calling a method that is only known at run time.

How do I add a delegate to an event?

Use the add accessor to add the delegate to the invocation list for the event. Dim dEmitted As [Delegate] = handler.CreateDelegate (tDelegate) miAddHandler.Invoke (exFormAsObj, New Object () {dEmitted}) Show the form. Clicking on the form causes the two delegates to be invoked.

What is the difference between event-based and delegate-based design?

By comparison, delegates are often passed as parameters and stored as private class members, if they are stored at all. That event listeners have longer lifetimes is a slightly weaker justification. However, you may find that event-based designs are more natural when the event source will be raising events over a long period of time.

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