This seminar will make you familiar with the exception handling concepts in .Net. Anyone who has been working on any of the .net languages or has just started can join in to learn more here.

1. Understanding
Exception Handling in .net.
Presenter: Harsh Wardhan, Mindfire Solutions
Date: 29/10/2013

2. Agenda
- What is Exception?
- The try, the catch & the finally.
- A look into System.Exception class.
- Throwing Exception.
- Defining your own exception class.
- Best practices.
- Unhandled Exceptions.
- Debugging Exceptions.
Presenter: Harsh Wardhan, Mindfire Solutions

3. What is Exception?
- When a member fails to complete the task it is
supposed to perform as indicated by its name, it is
called an exception.
Presenter: Harsh Wardhan, Mindfire Solutions

4. The Try
- A Try block contains code that require:
- Common clean up operations.
- Exception recovery operations.
- A code that might potentially throw an
exception.
- A Try block should have at least one catch or finally
block associated with it.
- How much code should be added in a single try
block?
Presenter: Harsh Wardhan, Mindfire Solutions

5. The Catch
- Contains code to execute in response to an
exception.
- A try block can have multiple catch blocks.
- The expression after Catch keyword is catch type.
- CLR searches the catch type from top to bottom.
Presenter: Harsh Wardhan, Mindfire Solutions

6. The Catch
- What to do in a catch block?
– Re-throw same exception.
– Throw a different exception with richer
exception information to code higher up in the
call stack.
– Let the thread fall out of the bottom of the
catch block.
Presenter: Harsh Wardhan, Mindfire Solutions

7. The Finally
- It contains code that's guranteed to execute.
- Mostly contains clean up operations required by
actions taken in try block.
- Code in catch and finally blocks should be short
and should have likelihood of succeeding without
itself throwing an exception.
Presenter: Harsh Wardhan, Mindfire Solutions

8. A look into System.Exception
- Base class for all exceptions.
- All user and system defined exceptions derive from
System.Exception class.
- Important Properties of System.Exception:
- Message
- Data
- Source
- Stack-trace
- Target Site
- Help link
- Inner exception
Presenter: Harsh Wardhan, Mindfire Solutions

9. Throwing Exception
- Points to consider while throwing an exception:
– What exception derived type you need to
throw.
– What string message are you going to pass
to the exception type's constructor.
Presenter: Harsh Wardhan, Mindfire Solutions

10. Defining your own Exception
class
- Create your exception class when the error is
tightly bound to the class issuing the error.
- Your exception class should be shallow and wide.
Presenter: Harsh Wardhan, Mindfire Solutions

11. Defining your own Exception
class
- Best practices for creating Exception class:
– Should derive from ApplicationException
– Marked with <System.Seralizable> attribute
– Defines a default constructor
– Defines a constructor that sets inherited
message property.
– Defines a constructor to handle inner exception.
– Defines a constructor for serialization of your
type.
Presenter: Harsh Wardhan, Mindfire Solutions

12. Best Practices
- Use
–
–
–
finally block liberally.
Use finally to clean up from any operation.
Dispose objects to avoid resource leak.
Examples in our language compiler:
• Lock statement.
• Using statement.
• For each statement.
Presenter: Harsh Wardhan, Mindfire Solutions

13. Best Practices
- Don't Catch everything.
– When you catch an exception you are
actually saying one of these things:
• You expected this exeption.
• You understand why it occurred.
• You know how to deal with it.
Presenter: Harsh Wardhan, Mindfire Solutions

14. Best Practices
- NEVER leave an empty catch block.
- Always try to catch specific exceptions.
- Catch a System.Exception and execute some code
inside catch block as long as you re-throw the
exception.
Presenter: Harsh Wardhan, Mindfire Solutions

15. Unhandled Exceptions
- If no catch block matches the thrown exception
type, an unhandled exception occurs.
- Usually information gets logged in Event Log.
Presenter: Harsh Wardhan, Mindfire Solutions

16. Debugging Exceptions
- You can enable the exception to break the flow
when it occurs.
- Helps in finding the exceptions being swallowed.
- You can add your own exception.
Presenter: Harsh Wardhan, Mindfire Solutions

17. Question and
Answer
Presenter: Harsh Wardhan, Mindfire Solutions

18. Thank you
Presenter: Harsh Wardhan, Mindfire Solutions