>>>> Thoughts? >>> >>> I really hope we can find some project-neutral common ground, so that lots >>> of tools (Cython, f2py, numba, C extensions in NumPy and SciPy) can agree >>> on how to "unbox callables". >>> >>> A new extension type in NumPy would not fit this bill I feel. I've created >>> a specification for this; if a number of projects (the ones mentioned >>> above) agree on this or something similar and implement support, we could >>> propose a PEP and do it properly once it has proven itself. >>> >>> http://wiki.cython.org/enhancements/cep1000 >>> >>> In Cython, this may take the form >>> >>> def call_callback(object func): >>> cdef double (*typed_func)(int) >>> typed_func = func >>> return typed_func(4) >>> >>> ...it would be awesome if passing a Numba-compiled function just worked in >>> this example. >> >> Yes, I think we should go the Python PEP route. However, it will take some >> time to see that to completion (especially with ctypes already in >> existence). Dag, this would be a very good thing for you to champion >> however ;-) > > I was NOT proposing a PEP. > > The spec is created so that it can be implemented *now*, by the tools > "we" control (and still be very efficient). A "sci-PEP", if you will; a > mutual understanding between Cython, NumPy, numba (and ideally f2py, > which already has something similar, if anyone bothers). > > When this is implemented in all the tools we care about, we can propose > something even nicer as a PEP, but that's far down the road; it'll be > another couple of years before I'm on Python 3.
Perfect :-) We are on the same page.... > >> >> In the mean-time, I think we could do as Robert essentially suggested and >> just use Capsule Objects around an agreed-upon simple C-structure: >> >> int id /* Some number that can be used as a "type-check" */ >> void *func; >> char *string; >> >> We can then just create some nice functions to go to and from this form in >> NumPy ctypeslib and then use this while the Python PEP gets written and >> adopted. > > What is not clear to me is how one get from the Python callable to the > capsule. This varies substantially based on the tool. Numba would do it's work and create the capsule object using it's approach. Cython would use a different approach. I would also propose to have in NumPy some basic functions that go back-and forth between this representation, ctypes, and any other useful representations that might emerge. > > Or do you simply intend to pass a non-callable capsule as an argument in > place of the callback? I had simply intended to allow a non-callable capsule argument to be passed in instead of another call-back to any SciPy or NumPy function that can take a raw C-function pointer. Thanks, -Travis _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
