What error handling should be used in VB.NET?
Should one use the "On Error Goto ErrorHandler ... Exit Sub ErrHandler ... End Sub" pattern or should you use the "try { ... } catch { ... } finally { ... }" pattern?
views:
43answers:
4
+6
A:
"try { ... } catch { ... } finally { ...}" pattern by a long shot.
C#
try
{
// Do Something that may go wrong
}
catch (Exception ex)
{
//Do something with the error
}
finally
{
//Cleanup
}
or
VB
Try
// Do Something that may go wrong
Catch ex as Exception
//Do something with the error
Finally
//Cleanup
End Try
Barry
2010-06-15 08:01:49
+1, Except that the curly braces aren't part of VB!
Martin
2010-06-15 08:03:57
lol! This is very true - I was being extremely lazy there and copy and pasted from the OP. I have edited my answer to include both language examples.
Barry
2010-06-15 08:07:37
@barry: why choose the try catch pattern?
Craig Johnston
2010-06-15 08:08:38
@Craig There are so many reasons why you should use try catch. I personally find it more logical. Try doing this section of code, if it fails then catch the exception and carry on if you can. I find OnError extremely difficult to follow and very messy. There is nice article on MSDN about life without OnError http://msdn.microsoft.com/en-us/library/aa289194(VS.71).aspx
Barry
2010-06-15 08:14:28
@Barry: can you refer to the Err object when using "try ... catch" or are you forced to use the Exception object?
Craig Johnston
2010-06-15 08:20:21
@Craig Johnston: You should be using `Exceptions`, they are much more flexible that the old `Err`.
ho1
2010-06-15 08:25:00
@Craig No you use the Exception object. Although `Exception` should be the very last exception to catch. You should always list exceptions in order. So specific execptions come first flowing down to the general `Execpetion` last. So if you are connecting to SQL you should catch `SQLException` first as this will contain detailed error information specific to SQL.
Barry
2010-06-15 08:28:51
A:
On Error Goto ErrorHandler ... Exit Sub ErrHandler ... End Sub is from the VB6 days. Definitely go with Try... Catch... Finally...
Shevek
2010-06-15 08:16:44
A:
A little background
'On Error Goto' is the way things were done in VB 6 before the .Net days. The VB compiler still allows this so you can easily port old VB code to VB.Net. VB.Net is probably the only .Net language that supports this.
'Try Catch Finally' is the .Net way to do things and a lot more flexible allowing you to catch, wrap and rethrow exceptions. It allows for easier interoperation between components written in different languages and is a lot more readable when you do more complex error handling because you don't have goto's.
Mendelt
2010-06-15 08:16:56
A:
The most obvious reasons I can think of off the top of my head to steer clear of On Error GoTo... would have to be:
On Error GoTodoes not discriminate between types of exceptions.On Error GoTodoes not provide as much structure asTry/Catch/Finally(e.g., nesting oneTry/Catchblock within another).On Error GoTohas no counterpart toFinally(that I know of).
I'm sure in many cases, clever use of On Error GoTo could mimic the behavior that is built in to VB.NET's Try/Catch/Finally feature. But what would be the point?
Dan Tao
2010-06-15 08:27:00