Re: [Boost-users] Lack of release() in scoped_ptr and scoped_array

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2006-08-02 18:30:40

On Aug 2, 2006, at 1:59 PM, Milutin Jovanovic wrote:

>
> I finally decided to switch to boost from my own implementation of  
> some
> helper classes, and I noticed that scoped_ptr and scoped_array in  
> boost lack
> the release method(). I had to fall back to std::auto_ptr.
>
> However, this seems like such a basic and fundamental problem that  
> I have
> started to fear that I am missing something obvious... The usage I  
> got used
> to was something like this:
>
> {
>     scoped_ptr<A> temp( new A() );
>     verify( temp.get() ); // might throw
>     store_in_a_very_special_place( temp.get() ); // might throw; and I
> should keep ownership if thrown
>     temp.release();
> }
>
> I though this was good practice to make code exception safe. Sure I  
> could do
> it with try-catch but that gets messy if I allocate multiple  
> instances etc.
>
> So the question is:
>
> 1) is there something wrong with the concept of release()?

There's nothing wrong with release().

> 2) if release() is not evil, is there any other reason why is it  
> not in
> boost::scoped_*?

scoped_ptr wasn't designed for this use case.

Just use std::auto_ptr.  C++0X will have an improved version of it  
called std::unique_ptr (I hope).  If you want, you can google around  
for some emulations of it.  But I'd just use auto_ptr for this use  
case for now.

-Howard