Re: [boost] [utility/value_init] boost::value_initialized<T> direct-initialized?

Subject: Re: [boost] [utility/value_init] boost::value_initialized<T> direct-initialized?
From: Niels Dekker - address until 2010-10-10 (niels_address_until_2010-10-10_at_[hidden])
Date: 2010-03-31 05:34:41

Jeffrey Hellrung wrote:
> initialized<T> was actually my initial thought;
> I chose a crappy name on purpose ;)

Cool  :-)

>> I can think of two ways to implement boost::initialized<T>
>> (and adapt value_initialized<T> accordingly):
> [...]
>
> I'm partial to value_initialized being implemented
> in terms of initialized

Me too  :-)  I think there's a leak in the design when 
boost::initialized inherits publicly from boost::value_initialized. You 
know, currently any object held by value_initialized is either 
value-initialized or copy-constructed from another object held by 
value_initialized. So in the end, any such object originates from a 
value-initialized object. I would like to keep it that way!

> Also, your initialized<T> does not have a default constructor. This
> makes sense, but I'm just double-checking that this is a conscious
> decision and not an oversight.

No, it's an oversight, sorry! I did not test any code from my last mail!

BTW I'm not entirely sure if the initialized(T const&) constructor would 
need an "explicit" keyword. What do you think?  Should the following be 
forbidden?

   boost::initialized<int> i = 42;

If so, we might as well make it even more explicit, by adding a "tag" 
parameter of type direct_initialized_t to the constructor, as I proposed 
before at https://svn.boost.org/trac/boost/ticket/3472 so that users 
would have to explicitly specify that they want direct-initialization:

   boost::initialized<int> i(42, boost::direct_initialized);

What do you think?

Kind regards,

   Niels

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