Burlen,
Have you actually verified that the first instance of import_array() actually
gets called? Because the behavior suggests that it does not.
In PyTrilinos, I wrap the import_array() call inside a C++ singleton, and put
that singleton in a dynamic library that all my packages link to, thus insuring
that it gets called once and only once.
-Bill
On Nov 14, 2013, at 11:10 AM, Burlen Loring wrote:
> Hi David,
>
> Yes, that the situation. using your naming convention, in addtion to
> foo_wrap.c I have another file , say foo_convert.cxx, for massaging
> python data structures into our internal data structures. This source is
> compiled with a c++ compiler so that I can use templates to simplify
> handling the numerous types a user could throw at us. All of the sources
> are linked into the module's .so. I need to use various numpy functions
> in my data conversions functions that live in foo_convert.cxx. For
> example I'm using PyArray_Check because I need to discerne between numpy
> arrays, and python lists and tuples.
>
> What I'm confused about is that calls to numpy funtions from this file
> are segv'ing unless I add another call to import_array() made from
> foo_convert.cxx. I'd like to understand why that's necessary, and why
> the import_array() call in the module's init section in foo_wrap.c
> doesn't have any affect even though it's called first?
>
> Thanks
> Burlen
>
> On 11/13/2013 10:48 PM, David Froger wrote:
>> Hi Burlen,
>>
>> SWIG will generate a file named for example foo_wrap.c, which will
>> contains a call to import_array() inserted by SWIG because of the
>> %init %{
>> import_array();
>> %}
>> in the SWIG script.
>> So in the file foo_wrap.c (which will be compiled to a Python module
>> _foo.so), you should be able to used PyArray_Check without segfault.
>> Typically, PyArray_Check will be inserted in foo_wrap.c by a typemap,
>> for example a typemap from numpy.i .
>>
>> Do you use PyArray_Check in the foo_wrap.c or in another file? Is
>> PyArray_Check in called in another C library, that _foo.so is linked
>> with?
>>
>> David
>>
>> Quoting Burlen Loring (2013-11-14 02:21:19)
>>> Hi,
>>>
>>> I'd like to add numpy support to an existing code that uses swig. I've
>>> changed the source file that has code to convert python lists into
>>> native data from c to c++ so I can use templates to handle data
>>> conversions. The problem I'm having is a segfault on PyArray_Check
>>> called from my c++ source. Looking at things in the debugger the
>>> argument passed to it is indeed an intialized python list, my swig file
>>> has import_array() in it's init, and I've verified that it is getting
>>> called. adding a function in my c++ source to call import_array() a
>>> second time prevents the segfault. Could anyone explain why I need the
>>> import_array() in both places? If that's the correct way to handle it?
>>>
>>> Thanks
>>> Burlen
>>> _______________________________________________
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>>> NumPy-Discussion@scipy.org
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** Bill Spotz **
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