🚀 go-pugleaf

ajay@lehman.com (Ajay Kamdar) writes:

>The following example demonstrates why allowing exceptions to
>propogate out of destructors is more trouble than it is worth:
>
>   auto_ptr<X>  get_X()
>   {
>      auto_ptr<X> p    = new X;
>      auto_ptr<X> temp = new X;
>      BadIdea     b1; // throws an exception in dtor
>      BadIdea     b2; // throws an exception in dtor
>
>      // ... stuff
>
>      return p;
>   }
>
>When b2 is destructed, it throws an exception. So what happens
>next?
>
>Does the run time system try to continue to destruct b1, temp,
>and p?

Yes.

>If it does, b1's destructor is also going to thow an
>exception. If I interpret 15.5.1 in theApril '95 CD correctly
>(I don't have access to any later drafts), terminate() is called
>because of the exception propagating out of b1's destructor.

That's right.  I'm pretty sure this hasn't changed in the more recent drafts.

>If on the other hand the run time system abandons executing
>the other destuctors in get_X() after b2's destructor has
>thrown an exception,

Such an implementation would not be conforming.

(Incidentally, I agree quite strongly with the arguments voiced by
Ajay Kamdar in this thread.)

--
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WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
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