[Numpy-discussion] C extensions: is Py_XDECREF() needed when using PyArray_FromAny()
Sebastian Haase
haase at msg.ucsf.edu
Sun Jul 23 18:23:45 CDT 2006
Hi,
I'm converting SWIG typemap'ed C extensions from numarray to numpy.
I studied (and use parts of) numpy.i from the doc directory.
I noticed that there is no
decref for the TYPEMAP_INPLACE2 typemap. This uses a function
obj_to_array_no_conversion() which in turn just returns
the original PyObject* ( casted to a PyArrayObject* after some sanity
checks) It looks to me that in this case there should be an explicit
Py_INCREF() - in case the function is threaded (releases the Python
GIL) since it holds a pointer to that object's data .
(Alternatively) Travis suggested (at the
http://www.scipy.org/Converting_from_numarray wiki page) using
PyArray_FromAny - is this incrementing the ref.count (implicitely) ?
The numarray equivalent (NA_InputArray) IS incrementing the ref.count
(as far as I know...).
Furthermore on that same wiki page the PyArray_FromAny() is called
together with PyArray_DescrFromType(<type>).
After searching through the numpy source I found that in
blasdot/_dotblas.c (in dotblas_matrixproduct() )there is an explicit
Py_INCREF even on the dtype returned from PyArray_DescrFromType.
I would argue that ref.counting is always very tricky territory ;-)
Hopefully someone can enlighten me .
Thanks,
Sebastian Haase
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