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: Artyom Beilis (artyomtnk_at_[hidden])
Date: 2015-11-10 07:51:52

>On 2015-11-09 18:52, Marshall Clow wrote:
>

>[snip]
>I'm seeing lots of warnings about use of deprecated std::auto_ptr in >different libraries: Boost.DateTime, Boost.Locale, Boost.Signals. I've 
>attached the list of places where these warnings occur.
>[snip]
>

See... unlike Boost, most of the ordinary world still uses C++2003 and will use
it for a long time especially for existing projects.

Existing libraries like Boost.Locale support C++2003.

std::auto_ptr is perfect way to provide ownership move semantics
without rvalue reference despite the fact some may abuse it.

So when you do need have to have move semantics, auto_ptr needs to be
there.

Using 

#ifdef USING_CPP11
std::unique_ptr<foo> bar();
#else 
std::auto_ptr<foo> bar(); 
#endif

Both makes horrible code and adds huge binary compatibility issues that Boost has enough of them.

IMHO deprecation of std::auto_ptr was one of the biggest design mistakes of C++11 because 
it does not allow writing code that supports both C++03 and C++11.

std::auto_ptr isn't broken the way gets is, it is actually very good class with its limitations.
So Boost.Locale would keep using auto_ptr until another "smart guy" in C++1X/2X committee
would decide to break more good things and remove it entirely so there would be no choice.

Artyom Beilis