Catch exception not of a type

Question

Is there a difference when catching exceptions not of a type between :

try
{
    ...
}
catch (TaskCanceledException)
{
    throw;
}
catch (Exception exception)
{
    ...
}

and :

try
{
    ...
}
catch (Exception exception) when (!(exception is TaskCanceledException))
{
    ...
}

Answer 1

Yes, there is.

In the second block of code you are filtering on general exception type. It is not meant to be filtered, what happens if "TaskCanceledException" is thrown? you are not handling it and it will escalate to enclosing code. You are not really meant to filter anything on "Exception" type since it is the parent for all other type of exception and it is the last point of handling exception. A better option would be to create a custom exception and put them in separate block of catch and filter on them if needed.

The first option is more correct compared to the second one. Though you should not be throwing any exception and stay away from them, unless it is a complete deal breaker. On top of that what is the point of putting a catch block with Exception type bellow TaskCanceledException catch block which throws exception? You are basically telling that "I Would like to handle all exception" when using catch with Exception type, but at the same time you through one exception in exceptional case. Either throw the original exception or handle them.

Hope this makes sense.