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Subject: Re: [boost] [Exception] Why is there no non-constversionofget_error_info?
From: Adam Badura (abadura_at_[hidden])
Date: 2009-08-21 01:29:55

> Are you sure the reserve() will reduce the risk significantly? Note
> that boost::exception_ptr itself also allocates memory, not to mention
> the onNotify functions themselves, assuming they aren't trivial they
> could be allocating things as well.

    If onNotify throws due to lack of memory then it is just as if it threw
anything else. (Except for slightly larger risk of failure in throwing
MultiException due to lack of memory for the exception itself.)

    boost::current_exception and boost::exception_ptr operations do are
declared to not throw. I was surprised that boost::current_exception does
not throw even std::bad_alloc but documentation says that. So in case of
lack of memory it returns exception_ptr to std::bad_alloc. Not ideal however
still my main purpose was to continue notifying and then rethrow all the
exceptions again with as small risk (of another failure) as possible.

> Yes that's a good one though the stack trace should be captured in one
> go before you throw. The trouble is this isn't possible in a
> platform-independent way; I'm hoping someone will come up with
> platform-specific implementation. I will add this support as soon as
> it's available, I do believe it is a very valuable diagnostic tool.

    Yes. It would be better to get the stack trace before throwing. However
for now (and I guess for long) it is not possible. While adding stack trace
in catch blocks during unwinding is.
    As it comes to stack trace I have thought a lot about it but anything I
imagined required adding special code to the functions which are to be
stack-traced (so likely every). I guess this could come down to a single
auxiliary function call wrapped in a macro however still it is not a good
solution. And off-topic here. :)

> In fact yesterday I went ahead and implemented it on my system, seems
> fine. I'll do some more testing and I'll commit it to trunk soon.

    Nice surprise. Thanks.

    Adam Badura

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