Re: [boost] [interprocess] preparing containers

Subject: Re: [boost] [interprocess] preparing containers
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2008-12-02 12:10:36

Thorsten Ottosen wrote:
> Hi Ion,
> 
> Some of my students tried to use boost::circular_buffer with 
> Boost.Interprocess allocators. Apparently the docs does not mention 
> circular_buffer as one that is compatible with Boost.Interproccess.

I had never tested this and I've just tried to do an small example that 
does not compile.

> What do we need to do to make a container that support the special 
> allocators?

Change the code to avoid assuming allocator::pointer is T*. This is 
usually easy but tedious (replace raw pointer declarations with typedefs 
that come from the allocator, change some calls that need raw pointers 
(ptr), with "&*ptr" and similar...). The easiest way is to instantiate 
the container with a shared memory allocator and start "fixing" code....

> In particular, if I want to use boost::ptr_vector, then do I need to 
> have stateful allocators (both the normal container allocator, and the 
> clone_allocator)?

Sorry, I'm not familiar with ptr_containers. If you can give me some 
hints on what's clone_allocator for, I'll be glad to help you to make 
ptr_container compatible with shared memory allocators. Just one issue: 
shared memory does not support virtual functions, so I don't think 
polymorphic cloning will be usable at all.

Joaquín has successfully changed multiindex code to support Interprocess 
so maybe he knows better than anyone what's the best way to make an 
existing container compatible with Interprocess. For std-like containers 
changing pointer declarations and replacing some calls was enough.

Regards,

Ion