I am thinking about building a patch to implement user-provided ufunc evaluation for numexpr as was discussed in this thread http://www.mail-archive.com/numpy-discussion@scipy.org/msg26292.html. Does anyone have any advice for learning/understanding the numexpr source and/or suggestions about implementation? All advice is helpful :) Francesc Alted mentioned that Mark Wiebe's other NEP https://github.com/m-paradox/numpy/blob/mw_neps/doc/neps/deferred-ufunc-eval..., would provide this feature (along with many other benefits). It looks really amazing, but I don't have a good sense of how developed it is. Best Regards, John Salvatier