Re: [boost] [exception] current_exception mishandlingstandardexceptions

Subject: Re: [boost] [exception] current_exception mishandlingstandardexceptions
From: Adam Badura (abadura_at_[hidden])
Date: 2009-05-14 16:16:58

>>   Note that this would also solved problem in enable_current_exception 
>> with
>> virtual base classes that are not default constructible - mentioned in
>> earlier thread.
>
> It would, but I don't see a reason to use exception types without
> default constructors with Boost Exception. So, in my mind this problem
> is only theoretical.

    What about integrating with existing exception hierarchies? (I know the 
example I gave previously of my project is not such hierarchy... :)). But on 
the other hand existing hierarchies likely do not use virtual inheritance as 
you have already mentioned somewhere before if I am not mistaken.

    Still there are reasons. In cases someone wants extra care he/she cannot 
use Boost.Exception data injection because this always adds risk of double 
failure - lack of memory and std::bad_alloc (or even something unpredictable 
as if I am not mistaken Standard puts low requirements on implementations on 
what, when and where can be thrown and only recommends standard 
exceptions) - which would mask the original failure.
    In case of my example of storing DWORD with GetLastError result in a 
modern PC machine chances of lack of memory are extremely low. However when 
talking about embedded systems or exceptions with more (maybe even lots) of 
data this becomes important.

    So to sum up IMHO if the implementation already uses this mechanism and 
all the required work is to make it public and document it then I would do 
it even if I didn't see practical use at the moment (I feel a bit 
mathematician and I do recall theories which also seemed useless at the 
moment of creation but then became important... :)). And in this case it 
seems (at least IMO) there are justified and possible if not likely use 
cases (the ones I mentioned earlier in the post).
    But you are not me and I do not feel entitled to modify Boost.Exception 
on my own so the final choice is yours. Since it seems I am the first and 
only one requesting this then maybe after all it is not important enough.

    (And yes. I know I can modify my own Boost to make this change and use 
it but I don't think it is a good idea especially that I am not the only 
person working on the project and we do constantly update Boost version 
instead of sticking to one particular.)

    Adam Badura