Re: [boost] Boost and auto_ptr (was Boost 1.60.0 beta 1...)

Subject: Re: [boost] Boost and auto_ptr (was Boost 1.60.0 beta 1...)
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2015-11-11 00:51:58

On 11/11/2015 02:46, Artyom Beilis wrote:
> The point is that semantics of auto_ptr makes it clear who owns
> what, it works well for more than a decade and of course
> well known to users.

Anecdotal evidence suggests that many users of auto_ptr did not find its 
behaviour sufficiently well known to avoid using it in buggy ways.

The problem is that most of the ways to use it "wrong" arise out of 
default compiler behaviour that can kick in with seemingly innocent code 
when you simply forget to do certain things (like disable or reimplement 
the copy constructor).  Whereas unique_ptr will give you compiler errors 
until you fix the code, making it inherently safer, if at times a little 
more annoying.

Having said that, I do currently use auto_ptr (in a safe way) in some 
code of my own (since it came from C++03 roots, and is now dual 
compiled), and I'm a little sad about the decision to remove it entirely 
in the near future.  Deprecation makes sense though, and in my case at 
least it's relatively simple to replace with unique_ptr.

I suspect though that if it's not removed at some point, then people 
will continue using it incorrectly; this was probably a factor in the 
committee's decision to remove it rather than merely leaving it 
deprecated, and similarly for MS following suit.

> Applying the deprecated-to-removed transition in just a few years
> seems hasty. That impression comes from mentioned
>(http://blogs.msdn.com/b/vcblog/archive/2015/04/29/c-11-14-17-features-in-vs-2015-rc.aspx)
> indicating that the second "major version" after VS2015 (2019?)
> auto_ptr won't be available. If I understood it correctly, I found
> it concerning... but I feel common sense will prevail. :)

So, seven years is hasty? :)