Re: [Boost-users] [MultiIndex] how to rebuild index

Subject: Re: [Boost-users] [MultiIndex] how to rebuild index
From: Igor R (boost.lists_at_[hidden])
Date: 2012-02-23 15:04:08

> Briefly put, there is no way to do that. The only thing that will
> work, though it's not officially guaranteed by the implementation, is:
>
> * Modify ONE element without using replace() or modify() (by using a
> const_cast, basically.)
> * Before doing anything else with the container (except possibly
> accessing their elements through previously existing iterators and/or
> advance those iterators around), use modify() with a no-op functor,
> as you suggest.

I see...
Unfortunately, it doesn't fit my use-case. I store weak_ptr's, and my
key extractors have to return different results for expired and
non-expired weak_ptr's.

> But you just can't externally (with const_cast) modify a bunch
> of elements and then get the index to rebuild --the rebuilding machinery
> assumes that at most one element (the one you call modify() on) is out
> of place, so if other elements are shuffled as well you'll get
> some sort of undefined behavior: core dump, whatever.

What if I just copy all the elements to another container of the same
type? Will the iteration from begin() from end() work correctly?