Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

What is the recommended approach to ensure all subscribers of a multicast delegate are notified even if an exception is thrown?

1. Invoke the event directly from the event caller

2. Utilize the GetInvocationList method and manually invoke each handler

3. Catch the exception during invocation and proceed

4. Use a try-catch block around the delegate invocation

The correct answer is: Utilize the GetInvocationList method and manually invoke each handler

Utilizing the GetInvocationList method and manually invoking each handler is the recommended approach for ensuring that all subscribers of a multicast delegate are notified even if an exception occurs. This method allows you to obtain an array of delegates, representing each subscriber, and invoke them individually. By individually invoking each handler, you can manage exceptions on a per-handler basis. This ensures that even if one subscriber throws an exception, the subsequent handlers can still be executed. This is especially important in scenarios where the behavior of the remaining subscribers should not be affected by the failure of a single subscriber. In contrast, invoking the event directly without this method doesn't provide any error handling capability. Catching exceptions during invocation without taking any further action may result in some subscribers not being notified at all if an error occurs during their execution, making it ineffective in ensuring complete notification. Using a try-catch block around the delegate invocation might manage exceptions, but if this approach is used without obtaining the invocation list first, some handlers might be skipped altogether if one fails, which undermines the goal of notifying all subscribers.