[Numpy-discussion] C extensions: is Py_XDECREF() needed when using PyArray_FromAny()
oliphant.travis at ieee.org
Mon Jul 24 14:29:15 CDT 2006
Sebastian Haase wrote:
> 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 .
Probably, true. The numpy.i typemaps are not thoroughly reference-count
> (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...).
Yes, you get back a new reference from PyArray_FromAny.
> 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.
PyArray_FromAny consumes a reference to the PyArray_Descr * object
(which is a Python object). Thus, because PyArray_FromAny is called
twice with the same data-type object, there is a need to increment it's
More information about the Numpy-discussion