[Mono-devel-list] Hidden Exceptions
jonpryor at vt.edu
Wed Feb 16 07:04:52 EST 2005
On Wed, 2005-02-16 at 03:14 -0500, Sébastien Robitaille wrote:
> I discovered that there are 3 exceptions that are always thrown when
> starting any application (even a small "Hello World" program).
> The exceptions are the following:
>  System.OutOfMemoryException: Out of memory
>  System.NullReferenceException: A null value was found where an
> object instance was required
>  System.StackOverflowException: The requested operation caused a
> stack overflow.
These exceptions aren't thrown, they're constructed. There's a
Why are they constructed? So that they always exist so they can be
thrown. For example, if you're out of memory, can you really expect to
construct a new OutOfMemoryException object to throw? No, so you create
it at program startup and cache it for when you need it. The same is
similarly true for NullReferenceException and StackOverflowException.
> I was wondering if these were "real" exceptions or not... Any idea ?
Yes, they're real, and they're not thrown.
> BTW, Is there a better way to print the exceptions thrown by a program
> running under mono, without interfering with the execution of
> the program?
You could try using the --breakonex and --trace arguments to mono. I
haven't tried them, but it looks like this should work:
mono --trace=T:System.Exception app.exe
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