Given the number of times which a big integer library has been started, I'd be wary of suggesting it as a GSoC project.
I did not thought it would be so hard to be done.
Since there are already many C big integer libraries (with various licenses), I'd be far more interested in an expression template system that would let me hook in the operations I need. That way if I'm ok with LGPL I can just use GMP, for instance. Also, a naive implementation could be provided for testing and verification.
It sounds very good. And does not involve reinventing the wheel from scratch as would do a new implementation of big integers. You would recommend creating expression templates that will allow to bind operators (functions or functionals) and types(for example big integers from third party library) together using type traits and passing functional as template parameter, have I got your idea right?
I remember hearing that someone had started something like that, but I don't know its progress.
I will take a deeper look if anybody has done it already.
~ Scott
-- Kamil Witecki.