[pypy-dev] cppyy: C++ bindings for PyPy

[wlavrijsen at lbl.gov]

Hi,

as detailed in a couple of blog posts in the past (*), for some time now we
have been working on making C++ bindings through the Reflex package available
on PyPy, in the form of the "cppyy" module. Software is never done, and that
is true also in this case, but it has reached a level of maturity at which it
can be said to be usable. Initial docs are now up on:

    http://doc.pypy.org/en/latest/cppyy.html

with instructions on how to setup the reflex-support branch and how to test
it out. The documentation will be updated with more advanced and detailed
topics in the next couple of weeks or so.

There's a sizable (non-PyPy) set of unit tests that still need to be worked
through, thus development will steadily continue at its current pace. Still,
if you find that cppyy almost works for you except for a particular feature,
feel free to ask for it to be prioritized.

The biggest obstacle for most people (that are not in the field of HEP) will
be the current set of dependencies. Although the dependency set for cppyy is
really only Reflex, which could be distributed separately, for the CPython
equivalent code, the dependency set is a large portion of the ROOT class
library. The medium-term plan then is to use Cling, which is based on CLang
from llvm (http://root.cern.ch/drupal/content/cling) as the back-end. For
this, there will be a PyCling on CPython, and all as stand-alone projects to
remove the large dependency set.

More interesting though, having Cling on the back of the bindings allows
far more advanced features, such as dynamic setup of callbacks and cross
language inheritance to put Python code into C++ frameworks. This has been
prototyped successfully in Clings predecessor (CINT), but would be very hard
to do in Reflex.

Of course, an important reason for pushing this code out to the community
somewhat early, is that it allows anyone so interested to start hacking on
it and help shape it!

Best regards,
            Wim

(*) http://morepypy.blogspot.com/2011/08/wrapping-c-libraries-with-reflection.html
     http://morepypy.blogspot.com/2010/07/cern-sprint-report-wrapping-c-libraries.html
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WLavrijsen at lbl.gov    --    +1 (510) 486 6411    --    www.lavrijsen.net