Error handling in functions? how should I do it?

[MrPolite]

what's the proper way of doing error handling in a function? This is what I usually do:

Public Shared Sub ResizeImage(ByVal srcPath As String, ByVal destPath As String...
        Dim srcImage As Image
        Try
            srcImage = Image.FromFile(srcPath)
        Catch ex As Exception
            Throw New ArgumentException("Error opening the source image", "srcPath", ex)
        End Try
        srcImage.Dispose()
    End Sub

should I just let the code throw an exception by itself? or is it better to make a new exception like that?

[Edneeis]

If you aren't going to try to handle the error or if you plan on just passing the error up then I'd let it do it itself. In other words I wouldn't try to catch the error if I am only going to forward it on. Otherwise lets say you want the path to be only local and tested and it wasn't then I would have it throw its own exception.

[MrPolite]

k, so most the time you dont put error handlers in these kind of functions, right?

[Edneeis]

Right, at lest that is how I do it anyway. I usually only put error handling in functions if I will be trying something else in the event of an error or in is some custom error handling for the function. Another example of when I WOULD is if an argument must be within a certain range and isn't or an Enum is an invalid number.