How to find exceptions thrown by OpenReadAsync method

Question

Consider the following code:

using (IRandomAccessStream stream = await storageFile.OpenReadAsync())
{
    using (DataReader dataReader = new DataReader(stream))
    {
        uint length = (uint)stream.Size;
        await dataReader.LoadAsync(length);
        txtbox.Text = dataReader.ReadString(length);
    }
}

storageFile.OpenReadAsync may throw exception, System.IO.FileNotFoundException is one possible exception type. MSDN topic StorageFile.OpenReadAsync http://msdn.microsoft.com/en-us/library/windows/apps/windows.storage.storagefile.openreadasync doesn't contain list of exception types thrown by this method. How can I find this information from documentation? I can catch an Exception type, but this is poor programming practice.

Answer 1

In cases where it is impossible to find all list of exceptions I usually use approach from VS SDK ErrorHandler.IsCriticalException:

try
{
    // ...
}
catch(Exception e)
{
    if (ErrorHandler.IsCriticalException(e))
    {
        throw;
    }

    // log it or show something to user
}

You can decompile the Microsoft.VisualStudio.Shell.11.0.dll to find the list of exceptions, which ErrorHandler defines as Critical:

• StackOverflowException
• AccessViolationException
• AppDomainUnloadedException
• BadImageFormatException
• DivideByZeroException

In the case of Windows Runtime I think that it will be good also to verify some of the HResult values in Exception, like E_OUTOFMEMORY, E_ABORT, E_FAIL, and maybe something else.

Also I found that BugSense is awesome help for logging exceptions. I use it not only for unhandled exception, but also for situations like this, where I have no idea what this method can throw. It allows to send custom logging (including exceptions) with BugSenseHandler.Instance.LogException, so I just collect information about different kind of exceptions (including exceptions with some unexpected HResult) and make some improvements for my app in each release.