Re: [Boost-users] [optional] How to make boost::optional throw if trying to access uninitialized value

Subject: Re: [Boost-users] [optional] How to make boost::optional throw if trying to access uninitialized value
From: dariomt (dariomt_at_[hidden])
Date: 2009-07-10 04:12:10

Josh Kelley <joshkel <at> gmail.com> writes:

> 
> On Thu, Jul 9, 2009 at 1:13 PM, <dariomt <at> gmail.com> wrote:
> > I've seen in the docs that boost::optional asserts if you try to access an
uninitialized value.
> >
> > Is it possible to make it throw an exception instead? Even in release mode?
> 
> You can change BOOST_ASSERT's behavior by defining
> BOOST_ENABLE_ASSERT_HANDLER.  See
> http://www.boost.org/doc/libs/1_39_0/libs/utility/assert.html for
> details.
> 
> boost/assert.hpp can be included multiple times in a single
> translation unit, so if you want boost::optional to throw exceptions
> but other parts of Boost to still assert, you can define
> BOOST_ENABLE_ASSERT_HANDLER immediately before including
> boost/optional.hpp and undefine it immediately afterward.
> 
> Josh Kelley
> 

Thanks for the info!

I think it is not possible to have a specific boost::assertion_failed handler
for boost::optional and other handlers for other assertion failures in other
places, right?

That would mean that the exception I throw from the handler cannot mention the
fact that I am accessing an uninitialized value in a boost::optional. 

Maybe I should create my own my::safe_optional based on boost::optional but
checking for uninitialized access. 

Any ideas?