Re: [Boost-users] [MultiArray, Intrusive] Instantiating a multi_array of intrusive lists as a class member

Subject: Re: [Boost-users] [MultiArray, Intrusive] Instantiating a multi_array of intrusive lists as a class member
From: Jeffrey Lee Hellrung, Jr. (jeffrey.hellrung_at_[hidden])
Date: 2013-01-08 12:27:59

On Mon, Jan 7, 2013 at 2:11 PM, Jiri Vyskocil <svzj_at_[hidden]> wrote:

> Ah, evidently boost::multiarray expects its value_type to be
> copy-constructible (at least), which Boost.Intrusive data structures are
> not [1]: "Boost.Intrusive containers are non-copyable and non-assignable."
> Also explains the failure of std::vector< boost::intrusive::list >, too, in
> C++03 mode. In C++11 mode, I guess std::vector (and similar) are able to
> fall back to using the move constructors and assignment operators of the
> Boost.Intrusive data structures.
>
> - Jeff
>
> [1]
> http://www.boost.org/doc/libs/1_52_0/doc/html/intrusive/intrusive_vs_nontrusive.html
>
>
>
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>
>  OK. It makes sense, that the multi_array expects its values to be
> copy-constructible. Still I would like to use the intrusive list since this
> part of algorithm is particularly sensitive to cache locality issues and I
> cannot lose the multi_array interface - stuff like views for example -
> because I already use it everywhere.
>
> I know, I'm not going to copy the lists contained in the multi_array. Any
> ideas how to get an intrusive list inside the multi_array?
>
> I can only think of implementing the intrusive list myself usin plain old
> pointer and reimplementing parts of STL-like interface. But it seems like a
> long path...
>
> What about inheriting a class from intrusive list, providing a false copy
> constructor (which would i.e. throw an error when called to be safe)? Would
> something like this be possible?
>
>
I suppose it would be possible to either inherit (most hacky) or otherwise
wrap an intrusive list and give it a "false", unconditionally throwing copy
constructor, as you suggested. You can also wrap all your intrusive lists
in shared_ptr (easiest) or use a multiarray of bare pointers to intrusive
lists (as long as you manage their lifetime outside the multiarray). The
best and correct solution, of course, is to update Boost.Multiarray for
C++11, but that requires the most work :/

- Jeff