Re: [boost] [exception] current_exception mishandling standardexceptions

Subject: Re: [boost] [exception] current_exception mishandling standardexceptions
From: Peter Dimov (pdimov_at_[hidden])
Date: 2009-05-13 13:37:45

Adam Badura:

> 2)
>
>    Non-standard exceptions derived from standard exceptions are sliced by 
> current_exception. It detects those types by throwing and caching and thus 
> will catch also derived types (like null_pointer : public 
> std::invalid_argument). But during construction of internal structures the 
> standard exception type is used and thus copy construction slices the 
> original exception object.
>    If typeid was used instead of throwing/catching (or dynamic_cast) to 
> detect the type current_exception could at least detect that is will slice 
> the original object and use a different type so it would not pretend 
> everything is OK.

What would you gain from that? If you catch(invalid_argument) you want 
null_pointer to be caught; if current_exception translated it to something 
else, it wouldn't be.

current_exception can store something derived from invalid_argument, but 
what are the benefits of doing so? Either way, catching an invalid_argument 
works, catching a null_pointer doesn't.