Are nested Try/Catch blocks a bad idea?

by

There are certain circumstances where they’re a good idea, e.g. one try/catch for the whole method and another inside a loop as you want to handle the exception and continue processing the rest of a collection.

Really the only reason to do it is if you want to skip the bit that errored and carry on, instead of unwinding the stack and losing context. Opening multiple files in an editor is one example.

That said, exceptions should (as the name implies) be exceptional. A program should handle them but try to avoid them as part of normal execution flow. They’re computationally expensive in most languages (Python being one notable exception).

One other technique which can be useful is catching specific exception types…

Try
    'Some code to read from a file

Catch ex as IOException
    'Handle file access issues (possibly silently depending on usage)
Catch ex as Exception
    ' Handle all other exceptions.
    ' If you've got a handler further up, just omit this Catch and let the 
    ' exception propagate
    Throw
End Try

We also use nested try/catches in our error handling routines…

    Try
        Dim Message = String.Format("...", )
        Try
            'Log to database
        Catch ex As Exception
            'Do nothing
        End Try

        Try
            'Log to file
        Catch ex As Exception
            'Do nothing
        End Try
    Catch ex As Exception
        'Give up and go home
    End Try

More Related Contents:

  1. What do Option Strict and Option Explicit do?
  2. Clean up Excel Interop Objects with IDisposable
  3. Reference variables and objects elsewhere in a form
  4. Parse Delimited CSV in .NET
  5. Using related data stored in a 2 dimensional array
  6. Is the Microsoft.VisualBasic namespace “true .NET” code?
  7. How do you get a string from a MemoryStream?
  8. Which is generally best to use — StringComparison.OrdinalIgnoreCase or StringComparison.InvariantCultureIgnoreCase?
  9. How do I create an event handler for a programmatically created object in VB.NET?
  10. How to overcome StackOverflowException bypassing unhandled exception handling in .NET
  11. BitmapImage in WPF does lock file
  12. How to deserialize a JObject to .NET object
  13. Does End Using close an open SQL Connection
  14. Does this code prevent SQL injection?
  15. Option Strict On and .NET for VB6 programmers
  16. Deserialize using JSON.net
  17. Cause this VB6-like smell, which VB.NET allows, to error instead: WinFormType.InstanceProp=Value [DISABLE My.Forms]
  18. How to print datagridview table with its header in vb.net?
  19. How to draw a signature and save it to disc as a Bitmap?
  20. Form’s TransparencyKey leaves ghastly colored edging [closed]
  21. Redirect Trace output to Console
  22. Accept self-signed TLS/SSL certificate in VB.NET
  23. How to make a Windows Forms .NET application display as tray icon?
  24. LinqToSql declare and instantiate DataContext best practice?
  25. Process.Start a file without Extension
  26. Should I always use the AndAlso and OrElse operators?
  27. Is there a way to define an implicit conversion operator in VB.NET?
  28. .NET — Textbox control – wait till user is done typing
  29. How to post a file via HTTP post in vb.net
  30. How to securely store a connection string in a WinForms application?

Leave a Comment