Re: [Boost-users] [variant] how to get 1st bounded type

From: Ovanes Markarian (om_boost_at_[hidden])
Date: 2008-05-06 12:28:10

2008/5/6 Igor R. <igor_rubinov_at_[hidden]>:

>
> > First I was going to suggest you to use mpl::front to retrieve the first
> element of the type sequence, but the new variant doc does not state that
> the first element of the type sequence will be created in the variant's
> memory. I remember to read that it was once the case.
>
> At least, the document that appears at the site states so:
> [...]
>
> http://www.boost.org/doc/libs/1_35_0/doc/html/variant/design.html#variant.design.never-empty
>
> At least what I read here is following:
The Guarantee

All instances v of type
variant<http://www.boost.org/doc/libs/1_35_0/doc/html/boost/variant.html>
<T1,T2,...,TN> guarantee that v has constructed content of !!!one!!! of the
types !!!T*i!!!*, even if an operation on v has previously failed.

For me it means that it can be T2 or TN as well.
Regards,
Ovanes