Re: [boost] [STL + allocators] Bug?

Subject: Re: [boost] [STL + allocators] Bug?
From: Phil Bouchard (philippeb8_at_[hidden])
Date: 2016-02-18 19:09:02

On 02/18/2016 06:30 AM, Phil Endecott wrote:
> Phil Bouchard wrote:
>> I think [std::list etc] should make use of the allocator's specific
>> pointer
>
> In C++03, containers were allowed to assume that allocator::pointer
> == value_type*.  This is not true since C++11, where it should use
> allocator::pointer via allocator_traits.
>
> A subtlety is that in the code you posted you're dealing with node
> pointers, not value_type pointers.  I'm not sure what's going on there.
> My first thought was that you were looking at a pre-11 version of
> libstdc++, but I see a #if that suggests otherwise.  Maybe others
> can comment.
>
> You might like to look at how Boost.Container works.  It should use
> allocator::pointer even on C++03.
>
> Note that trying to use a smart pointer for allocator::pointer is
> unlikely to work in general, e.g. you can't use shared_ptr, because
> the semantics are not what the container expects.  The most common
> use for redefining allocator::pointer that I've seen is to store
> offset in memory-mapped files and similar.

Thanks for your input...  I am trying out boost::container::... right 
now and it is not a trivial task to use a smart pointers inside 
containers but I think it is possible.

I saw functions like to_raw_pointer() were user before calling the 
allocator's constructors & destructors... I believe this should be 
cleaned up sooner or later but for now I think I can survive by 
overloading only the allocate & deallocate functions.