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

Subject: Re: [boost] [utility/value_init] boost::value_initialized<T> direct-initialized?
From: Jeffrey Lee Hellrung, Jr. (jhellrung_at_[hidden])
Date: 2010-04-08 12:30:03

Stewart, Robert wrote:
> Fernando Cacciola wrote:
> 
>> I can imagine myself explaining that "initialize<T> m(v)"  does
>> direct-initialization, then that, OTOH, "initialized<T> m;" does
>> value-initialization, since there is no explicit
>> initialization in this case.
> 
> Why does initialized<T> need to have a default constructor?

Because if it wasn't default-constructible, why would you use it (when a 
T object would suffice)?

The motivating example (I believe) is when you have a class member of 
type initialized<T>, and you want the default constructor of the class 
to value initialize the data member.  (You also want a (const T&) 
constructor that direct intializes the data member; otherwise, 
value_initialized<T> would suffice.)

- Jeff