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Subject: Re: [boost] Interest in StaticVector - fixed capacity vector
From: Andrew Hundt (athundt_at_[hidden])
Date: 2011-10-12 21:23:11

> > The design choice between throwing and undefined behaviour (in release
> > builds, where asserts become no-ops) boils down to the choice of who
> > should check the precondition: the callee, or the caller. Tradition has
> > favoured the caller checking the precondition whenever possible, because
> > the caller has more information and can sometimes check more efficiently
> > (e.g. by eliding the check altogether in cases where it already knows the
> > precondition is met).
> And sometimes is less efficient. For instance, if you are populating
> from StaticVector from list iterators (or any non-random access
> iterators), it's an O(n) check ahead of time or a complicated wrapper
> around a one-at-a-time insert. (Note: this is a bug in the current
> implementation of StaticVector, as its iterator constructor currently
> requires random access iterators).
Does this mean that in any of the functions where I have two iterators, I
should separately implement one for boost::single_pass_traversal_tag and
another for boost::random_access_traversal_tag?

I assume I want to simply check the distance between two random access
iterators and return immediately if the size is too big.
Then, if it isn't random access I should just start copying and check if
I've run out of space on each element that is added. Is this correct?

On this topic, what is the difference between
boost::random_access_traversal_tag and std::random_access_iterator_tag, and
should I implement both?

Andrew Hundt

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