Re: [boost] boost::mpl::for_each and value_initialized

Subject: Re: [boost] boost::mpl::for_each and value_initialized
From: David Abrahams (dave_at_[hidden])
Date: 2009-09-24 09:56:39

on Fri Sep 04 2009, "Aleksey Gurtovoy" <agurtovoy-AT-meta-comm.com> wrote:

> Hi Peter,
>
>> what is the use of value_initialized in boost::mpl::for_each?
>> It should be sufficient if the value is initialized by the constructor.
>
> In theory, yes. In practice, at the time when the code was authored,
> it wasn't -- see http://www.boost.org/doc/libs/1_40_0/libs/utility/value_init.htm
>
>
>> value_initialized() calls memset() in before calling the constructor.
>
> Apparently this change was introduced in 1.35 release:
>
>    "New versions of value_initialized (Boost release version 1.35 or
>     higher) offer a workaround to these issues: value_initialized will
>     now clear its internal data, prior to constructing the object that
>     it contains."
>
> The fact that it's done unconditionally (as opposite only for compilers
> with the discussed issues) is IMHO a bug.

Agreed.  Is this being fixed?

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com