Subject: Re: [boost] Proposal: Monotonic Containers
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-06-09 09:44:44
On Tuesday, June 09, 2009 9:34 AM
> Stewart, Robert escribió:
> > There's a problem with using an allocator for the node based
> > containers: they use the allocator to allocate the elements
> > but not the nodes. That implies free store (de)allocations
> > for the nodes which is contrary to the intended purpose of
> > this proposal.
> Umm, I beg to differ. If we have a node-based container
> xxx<T,...,custom_allocator<T> >
> and node<T> is the internal node type, the container is required
> to do the allocation using an allocator of type
> custom_allocator<T>::rebind<node<T> >::other.
> The container is not allowed to do any kind of allocation using
> other means than the custom_allocator<X> family of allocators.
If custom_allocator<node<T> > is not specialized to do the same as custom_allocator<T>, or to use the same memory pool, then it doesn't fit the proposal. It is possible that the primary specialization uses the free store and only specific specializations use the custom pool. Since you can't know the node type of a standard container, you can't specialize for it. Since the node is likely of a different size than the element type, the nodes cannot be put into the same pool as the elements, which greatly complicates using an allocator for the proposed purpose.
Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP http://www.sig.com
IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.
Boost list run by bdawes at acm.org, david.abrahams at rcn.com, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk