Re: [boost] Patch to value_initialized

Subject: Re: [boost] Patch to value_initialized
From: Niels Dekker - address until 2010-10-10 (niels_address_until_2010-10-10_at_[hidden])
Date: 2010-05-13 10:14:26

On 2010-05-13 12:32, Christopher Jefferson wrote:
> I just wanted to make people away of a suggested patch to
> value_initialized, explicitly adding the default constructor,
> copy constructor and operator=, given in
> https://svn.boost.org/trac/boost/ticket/4213 .

First of all, sorry for causing the regression failure. It was caused by 
my commit [61883], which added initialized<T>, and reimplemented 
value_initialized<T> in terms of initialized<T>:
https://svn.boost.org/trac/boost/changeset/61883

Please note that this commit hasn't yet been merged to the release 
branch. You see, there are no value_init_test failures at 
http://www.boost.org/development/tests/release/developer/utility.html 
So it's merely a trunk issue.

> The default constructor is necessary for clang and comeau (in strict
> mode) to allow const value_initialized values without an explicit
> value. I believe this is correct behaviour, but other compilers are
> more lack.
>
> I believe this patch is small and should work fine, but I know that
> this has been a very sensitive bit of code in the past, prone to
> kicking up minor compiler problems.

Your value_initialized() default constructor is fine with me, but 
personally I'd rather not have the user-defined copy constructor and 
operator=. You know, value_initialized<T> does not need to be 
CopyConstructible or CopyAssignable. That just depends on whether T is.

> My preferred option would be to try submitting this patch to trunk
> and see if any tester kicks up a fuss. If any do, then I am happy
> to introduce some macros.

I don't expect your default constructor to cause any compiler problems.

Is it okay to you if I just add the default constructor you're proposing 
to the trunk?

Kind regards,

    Niels

-- 
Niels Dekker
http://www.xs4all.nl/~nd/dekkerware
Scientific programmer at LKEB, Leiden University Medical Center