[Numpy-discussion] Getting C-function pointers from Python to C

Dag Sverre Seljebotn d.s.seljebotn@astro.uio...
Thu Apr 19 10:28:36 CDT 2012

On 04/19/2012 04:17 PM, Travis Oliphant wrote:
> Thanks for the status update.  A couple of weeks is a fine timeline to wait.
> Are you envisioning that the ufuncs in NumPy would have the nativecall attribute?

I'm envisioning that they would be able to support CEP 1000, yes, but I 
don't think they would necesarrily use the ufunc machinery or existing 
implementation -- just a namespace mechanism, a way of getting the 
"np.sin" to map to the libc (or npymath?) "sin" function.

Currently when translating

In Numba, if somebody writes:

from numpy import sin

def f(x):
     return sin(x * x)

Then, at numbafication-time, you can presumably lift the "sin" object 
out of the module scope, look at it, and through CEP 1000 figure out 
that there's a "d->d" function pointer inside the sin object, and use 
that a) for type inference, b) embed a jump to the function in the 
generated code.

(If somebody rebinds "sin" after the numba decorator has run, they get 
to keep the pieces)

I don't know how you planned on doing this now, perhaps special casing a 
few NumPy functions? The nice thing is that through CEP 1000, numba can 
transparently support whatever special function I write in Cython, and 
dispatch to it *fast*.


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