Catch exceptions in multi threads and processes program

Question

I'm trying to catch some specific exception. The problem is that my program is complex and can hide this exception as a 'primary' exception or as an inner exception inside an aggregated exception. (it could also be an inner of an inner exception and so on) How do I catch this in an elegant way? What I've done so far

            catch (Exception e) when (e.InnerException is MyOwnSpecialErrorException)
            {
                var e1 = e.InnerException as MyOwnSpecialErrorException;
                success = false;
                exception = e1;
            }

and also:

        catch (MyOwnSpecialErrorException e) 
        {
            success = false;
            exception = e;
        }

Of course here I only take care in the case of one nested inner exception, and also this assumes that it is the first inner exception. Can someone think of some way?

What if the `AggregateException` contains a `MyOwnSpecialErrorException` along with other exceptions? Do you want to ignore the other exceptions in this case? — Theodor Zoulias, May 22 '22 at 07:59
@TheodorZoulias yes, I would want to ignore them. One MyOwnSpecialErrorException is enough no matter what other exceptions occurred — Nika, May 22 '22 at 08:04

score 2 · Accepted Answer · answered May 22 '22 at 08:13

2

That's the more concise syntax I can think of, featuring the is operator:

bool success;
MyOwnSpecialErrorException exception;
try
{
    //...
}
catch (AggregateException aex)
    when (aex.Flatten().InnerExceptions.OfType<MyOwnSpecialErrorException>()
        .FirstOrDefault() is MyOwnSpecialErrorException myEx)
{
    success = false; exception = myEx;
}
catch (MyOwnSpecialErrorException ex)
{
    success = false; exception = ex;
}
catch
{
    success = true; // Ignore all other exceptions
}

answered May 22 '22 at 08:13

Theodor Zoulias

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why do we need the .Flatten() part instead of access .InnerExceptions? – Nika May 22 '22 at 09:40
@Nika if you know for sure that the `AggregateException` can be at most one level deep, you can get away without the [`Flatten`](https://learn.microsoft.com/en-us/dotnet/api/system.aggregateexception.flatten). – Theodor Zoulias May 22 '22 at 09:46

Catch exceptions in multi threads and processes program

1 Answers1