From vincent.vande.vyvre at telenet.be  Wed Aug  3 04:58:09 2016
From: vincent.vande.vyvre at telenet.be (Vincent Vande Vyvre)
Date: Wed, 3 Aug 2016 10:58:09 +0200
Subject: [C++-sig] Exporting a c++ buffer type.
Message-ID: <d5fbf2e2-e4f6-776f-cae2-25074ee1abbd@telenet.be>

Hi,

I'm porting a lib to Python-3.

This code works with Python-2

------------------------------------------------------
const std::string Image::getExifThumbnailData()
{
     Exiv2::DataBuf buffer = _getExifThumbnail()->copy();
     // Copy the data buffer in a string.
     // First allocate the memory for the whole string...
     std::string data = std::string(buffer.size_, ' ');
     // ... then fill it with the raw data.
     for(unsigned int i = 0; i < buffer.size_; ++i)
     {
         data[i] = buffer.pData_[i];
     }
     return data;
-----------------------------------------------------

The object Exiv2::DataBuf contain the pixel's values of an image 
[R,G,B,R,G,B,...]
It is described here (1)

With Python-3 I get this error:

     buf_ = self._metadata._image._getExifThumbnailData()
TypeError: No to_python (by-value) converter found for C++ type: 
std::vector<char, std::allocator<char> >


Then, I've made some tests with memoryView, like this:

-----------------------------------------------------
boost::python::object Image::getExifThumbnailData()
{
     Exiv2::DataBuf buffer = _getExifThumbnail()->copy();
     Py_ssize_t size = buffer.size_;
     Py_buffer py_buffer;
     PyObject exporter;
     int res = PyBuffer_FillInfo(&py_buffer, &exporter, &buffer.pData_, 
size,
                                 true, PyBUF_CONTIG_RO);
     if (res == -1) {
         PyErr_Print();
         exit(EXIT_FAILURE);
     }
     boost::python::object memoryView(boost::python::handle<>
                                     (PyMemoryView_FromMemory
                                     (&exporter, size, PyBUF_READ)));
     return memoryView;
}
----------------------------------------------------
But that doesn't compile.

src/exiv2wrapper.cpp: In member function ?boost::python::api::object 
exiv2wrapper::Image::getExifThumbnailData()?:
src/exiv2wrapper.cpp:504:65: error: cannot convert ?PyObject* {aka 
_object*}? to ?char*? for argument ?1? to ?PyObject* 
PyMemoryView_FromMemory(char*, Py_ssize_t, int)?
                                      (&exporter, size, PyBUF_READ)));


(1) DataBuf: http://www.exiv2.org/doc/classExiv2_1_1DataBuf.html


Regards,


Vincent


From matt.p.conte at gmail.com  Thu Aug  4 13:10:23 2016
From: matt.p.conte at gmail.com (Matthew Conte)
Date: Thu, 4 Aug 2016 13:10:23 -0400
Subject: [C++-sig] Segmentation Fault (core dumped) on Python 3.5.2 but not
 Python 2.7.12
Message-ID: <CAFwmYYjxXXVQV=6Wv8x_q4Uc2GjogR1OR_JSURhP3kCMrEb-gQ@mail.gmail.com>

So I'm trying to create a boost python module that simply creates and
returns a numpy array,
but the function crashes (sometimes) and it doesn't ever seem to crash on
Python 2.

Here's the source code I made:

#include <boost/python.hpp>
#include <numpy/ndarrayobject.h>

using namespace boost::python;

object create_numpy_array() {
npy_intp dims = 1;
long* data = new long[1];
data[0] = 1;
PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR, data);
boost::python::handle<> handle(obj);
boost::python::numeric::array arr(handle);
return arr.copy();
}

BOOST_PYTHON_MODULE(create) {
import_array();
numeric::array::set_module_and_type("numpy", "ndarray");
def("numpy_array", &create_numpy_array);
}


using a simple python script to test:

import create
print(create.numpy_array())


The stack trace indicates that the crash occurs on a boost::python::handle
destructor trying to decrease the ref count of a PyObject with a ref count
of 0.

I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.

Thank you.
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From stefan at seefeld.name  Thu Aug  4 13:14:58 2016
From: stefan at seefeld.name (Stefan Seefeld)
Date: Thu, 4 Aug 2016 13:14:58 -0400
Subject: [C++-sig] Segmentation Fault (core dumped) on Python 3.5.2 but
 not Python 2.7.12
In-Reply-To: <CAFwmYYjxXXVQV=6Wv8x_q4Uc2GjogR1OR_JSURhP3kCMrEb-gQ@mail.gmail.com>
References: <CAFwmYYjxXXVQV=6Wv8x_q4Uc2GjogR1OR_JSURhP3kCMrEb-gQ@mail.gmail.com>
Message-ID: <32f9c08d-2d65-c1b5-ca1a-1055f3784240@seefeld.name>

Hi Matthew,

would you mind submitting an issue on
https://github.com/boostorg/python/issues for this.

Thanks,
        Stefan

On 04.08.2016 13:10, Matthew Conte wrote:
> So I'm trying to create a boost python module that simply creates and
> returns a numpy array, 
> but the function crashes (sometimes) and it doesn't ever seem to crash
> on Python 2.
>
> Here's the source code I made:
>
> #include <boost/python.hpp>
> #include <numpy/ndarrayobject.h>
>
> using namespace boost::python;
>
> object create_numpy_array() {
> npy_intp dims = 1;
> long* data = new long[1];
> data[0] = 1;
> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR,
> data);
> boost::python::handle<> handle(obj);
> boost::python::numeric::array arr(handle);
> return arr.copy();
> }
>
> BOOST_PYTHON_MODULE(create) {
> import_array();
> numeric::array::set_module_and_type("numpy", "ndarray");
> def("numpy_array", &create_numpy_array);
> }
>
>
> using a simple python script to test:
>
> import create
> print(create.numpy_array())
>
>
> The stack trace indicates that the crash occurs on a
> boost::python::handle destructor trying to decrease the ref count of a
> PyObject with a ref count of 0.
>
> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
>
> Thank you.
>
>
> _______________________________________________
> Cplusplus-sig mailing list
> Cplusplus-sig at python.org
> https://mail.python.org/mailman/listinfo/cplusplus-sig


-- 

      ...ich hab' noch einen Koffer in Berlin...


From matt.p.conte at gmail.com  Thu Aug  4 13:16:58 2016
From: matt.p.conte at gmail.com (Matthew Conte)
Date: Thu, 4 Aug 2016 13:16:58 -0400
Subject: [C++-sig] Segmentation Fault (core dumped) on Python 3.5.2 but
 not Python 2.7.12
In-Reply-To: <32f9c08d-2d65-c1b5-ca1a-1055f3784240@seefeld.name>
References: <CAFwmYYjxXXVQV=6Wv8x_q4Uc2GjogR1OR_JSURhP3kCMrEb-gQ@mail.gmail.com>
 <32f9c08d-2d65-c1b5-ca1a-1055f3784240@seefeld.name>
Message-ID: <CAFwmYYjN4CDP4sLAs0C4JACFHPOxLeDyPX+LoSpv4NdGVfhGEQ@mail.gmail.com>

I will, thank you.

On Thu, Aug 4, 2016 at 1:14 PM, Stefan Seefeld <stefan at seefeld.name> wrote:

> Hi Matthew,
>
> would you mind submitting an issue on
> https://github.com/boostorg/python/issues for this.
>
> Thanks,
>         Stefan
>
> On 04.08.2016 13:10, Matthew Conte wrote:
> > So I'm trying to create a boost python module that simply creates and
> > returns a numpy array,
> > but the function crashes (sometimes) and it doesn't ever seem to crash
> > on Python 2.
> >
> > Here's the source code I made:
> >
> > #include <boost/python.hpp>
> > #include <numpy/ndarrayobject.h>
> >
> > using namespace boost::python;
> >
> > object create_numpy_array() {
> > npy_intp dims = 1;
> > long* data = new long[1];
> > data[0] = 1;
> > PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR,
> > data);
> > boost::python::handle<> handle(obj);
> > boost::python::numeric::array arr(handle);
> > return arr.copy();
> > }
> >
> > BOOST_PYTHON_MODULE(create) {
> > import_array();
> > numeric::array::set_module_and_type("numpy", "ndarray");
> > def("numpy_array", &create_numpy_array);
> > }
> >
> >
> > using a simple python script to test:
> >
> > import create
> > print(create.numpy_array())
> >
> >
> > The stack trace indicates that the crash occurs on a
> > boost::python::handle destructor trying to decrease the ref count of a
> > PyObject with a ref count of 0.
> >
> > I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
> >
> > Thank you.
> >
> >
> > _______________________________________________
> > Cplusplus-sig mailing list
> > Cplusplus-sig at python.org
> > https://mail.python.org/mailman/listinfo/cplusplus-sig
>
>
> --
>
>       ...ich hab' noch einen Koffer in Berlin...
>
> _______________________________________________
> Cplusplus-sig mailing list
> Cplusplus-sig at python.org
> https://mail.python.org/mailman/listinfo/cplusplus-sig
>
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From foxtog at gmail.com  Fri Aug  5 11:37:19 2016
From: foxtog at gmail.com (foxtog at gmail.com)
Date: Fri, 5 Aug 2016 19:37:19 +0400
Subject: [C++-sig] Cplusplus-sig Digest, Vol 94, Issue 2
In-Reply-To: <mailman.9.1470412802.3831.cplusplus-sig@python.org>
References: <mailman.9.1470412802.3831.cplusplus-sig@python.org>
Message-ID: <4D8730C2-DE71-45A7-8305-7B0157554E38@gmail.com>

The problem doesn't have anything to do with boost.python. The thing is in initializing numpy API pointer specifically PyArray_API*. If you print this pointer before creating the array, it'll turn out to be null. If you move import_array function just before the array creation call, it should work. You can find more details here 
http://docs.scipy.org/doc/numpy/reference/c-api.array.html in Miscellaneous section at the bottom. 

Regards,
Alexandra

> 05 ???. 2016 ?., ? 20:00, cplusplus-sig-request at python.org ???????(?):
> 
> Send Cplusplus-sig mailing list submissions to
>    cplusplus-sig at python.org
> 
> To subscribe or unsubscribe via the World Wide Web, visit
>    https://mail.python.org/mailman/listinfo/cplusplus-sig
> or, via email, send a message with subject or body 'help' to
>    cplusplus-sig-request at python.org
> 
> You can reach the person managing the list at
>    cplusplus-sig-owner at python.org
> 
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Cplusplus-sig digest..."
> 
> 
> Today's Topics:
> 
>   1. Segmentation Fault (core dumped) on Python 3.5.2 but not
>      Python 2.7.12 (Matthew Conte)
>   2. Re: Segmentation Fault (core dumped) on Python 3.5.2 but not
>      Python 2.7.12 (Stefan Seefeld)
>   3. Re: Segmentation Fault (core dumped) on Python 3.5.2 but not
>      Python 2.7.12 (Matthew Conte)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Thu, 4 Aug 2016 13:10:23 -0400
> From: Matthew Conte <matt.p.conte at gmail.com>
> To: cplusplus-sig at python.org
> Subject: [C++-sig] Segmentation Fault (core dumped) on Python 3.5.2
>    but not Python 2.7.12
> Message-ID:
>    <CAFwmYYjxXXVQV=6Wv8x_q4Uc2GjogR1OR_JSURhP3kCMrEb-gQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
> 
> So I'm trying to create a boost python module that simply creates and
> returns a numpy array,
> but the function crashes (sometimes) and it doesn't ever seem to crash on
> Python 2.
> 
> Here's the source code I made:
> 
> #include <boost/python.hpp>
> #include <numpy/ndarrayobject.h>
> 
> using namespace boost::python;
> 
> object create_numpy_array() {
> npy_intp dims = 1;
> long* data = new long[1];
> data[0] = 1;
> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR, data);
> boost::python::handle<> handle(obj);
> boost::python::numeric::array arr(handle);
> return arr.copy();
> }
> 
> BOOST_PYTHON_MODULE(create) {
> import_array();
> numeric::array::set_module_and_type("numpy", "ndarray");
> def("numpy_array", &create_numpy_array);
> }
> 
> 
> using a simple python script to test:
> 
> import create
> print(create.numpy_array())
> 
> 
> The stack trace indicates that the crash occurs on a boost::python::handle
> destructor trying to decrease the ref count of a PyObject with a ref count
> of 0.
> 
> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
> 
> Thank you.
> -------------- next part --------------
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> 
> ------------------------------
> 
> Message: 2
> Date: Thu, 4 Aug 2016 13:14:58 -0400
> From: Stefan Seefeld <stefan at seefeld.name>
> To: cplusplus-sig at python.org
> Subject: Re: [C++-sig] Segmentation Fault (core dumped) on Python
>    3.5.2 but not Python 2.7.12
> Message-ID: <32f9c08d-2d65-c1b5-ca1a-1055f3784240 at seefeld.name>
> Content-Type: text/plain; charset=windows-1252
> 
> Hi Matthew,
> 
> would you mind submitting an issue on
> https://github.com/boostorg/python/issues for this.
> 
> Thanks,
>        Stefan
> 
>> On 04.08.2016 13:10, Matthew Conte wrote:
>> So I'm trying to create a boost python module that simply creates and
>> returns a numpy array, 
>> but the function crashes (sometimes) and it doesn't ever seem to crash
>> on Python 2.
>> 
>> Here's the source code I made:
>> 
>> #include <boost/python.hpp>
>> #include <numpy/ndarrayobject.h>
>> 
>> using namespace boost::python;
>> 
>> object create_numpy_array() {
>> npy_intp dims = 1;
>> long* data = new long[1];
>> data[0] = 1;
>> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR,
>> data);
>> boost::python::handle<> handle(obj);
>> boost::python::numeric::array arr(handle);
>> return arr.copy();
>> }
>> 
>> BOOST_PYTHON_MODULE(create) {
>> import_array();
>> numeric::array::set_module_and_type("numpy", "ndarray");
>> def("numpy_array", &create_numpy_array);
>> }
>> 
>> 
>> using a simple python script to test:
>> 
>> import create
>> print(create.numpy_array())
>> 
>> 
>> The stack trace indicates that the crash occurs on a
>> boost::python::handle destructor trying to decrease the ref count of a
>> PyObject with a ref count of 0.
>> 
>> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
>> 
>> Thank you.
>> 
>> 
>> _______________________________________________
>> Cplusplus-sig mailing list
>> Cplusplus-sig at python.org
>> https://mail.python.org/mailman/listinfo/cplusplus-sig
> 
> 
> -- 
> 
>      ...ich hab' noch einen Koffer in Berlin...
> 
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Thu, 4 Aug 2016 13:16:58 -0400
> From: Matthew Conte <matt.p.conte at gmail.com>
> To: "Development of Python/C++ integration" <cplusplus-sig at python.org>
> Subject: Re: [C++-sig] Segmentation Fault (core dumped) on Python
>    3.5.2 but not Python 2.7.12
> Message-ID:
>    <CAFwmYYjN4CDP4sLAs0C4JACFHPOxLeDyPX+LoSpv4NdGVfhGEQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
> 
> I will, thank you.
> 
>> On Thu, Aug 4, 2016 at 1:14 PM, Stefan Seefeld <stefan at seefeld.name> wrote:
>> 
>> Hi Matthew,
>> 
>> would you mind submitting an issue on
>> https://github.com/boostorg/python/issues for this.
>> 
>> Thanks,
>>        Stefan
>> 
>>> On 04.08.2016 13:10, Matthew Conte wrote:
>>> So I'm trying to create a boost python module that simply creates and
>>> returns a numpy array,
>>> but the function crashes (sometimes) and it doesn't ever seem to crash
>>> on Python 2.
>>> 
>>> Here's the source code I made:
>>> 
>>> #include <boost/python.hpp>
>>> #include <numpy/ndarrayobject.h>
>>> 
>>> using namespace boost::python;
>>> 
>>> object create_numpy_array() {
>>> npy_intp dims = 1;
>>> long* data = new long[1];
>>> data[0] = 1;
>>> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR,
>>> data);
>>> boost::python::handle<> handle(obj);
>>> boost::python::numeric::array arr(handle);
>>> return arr.copy();
>>> }
>>> 
>>> BOOST_PYTHON_MODULE(create) {
>>> import_array();
>>> numeric::array::set_module_and_type("numpy", "ndarray");
>>> def("numpy_array", &create_numpy_array);
>>> }
>>> 
>>> 
>>> using a simple python script to test:
>>> 
>>> import create
>>> print(create.numpy_array())
>>> 
>>> 
>>> The stack trace indicates that the crash occurs on a
>>> boost::python::handle destructor trying to decrease the ref count of a
>>> PyObject with a ref count of 0.
>>> 
>>> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
>>> 
>>> Thank you.
>>> 
>>> 
>>> _______________________________________________
>>> Cplusplus-sig mailing list
>>> Cplusplus-sig at python.org
>>> https://mail.python.org/mailman/listinfo/cplusplus-sig
>> 
>> 
>> --
>> 
>>      ...ich hab' noch einen Koffer in Berlin...
>> 
>> _______________________________________________
>> Cplusplus-sig mailing list
>> Cplusplus-sig at python.org
>> https://mail.python.org/mailman/listinfo/cplusplus-sig
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> 
> Subject: Digest Footer
> 
> _______________________________________________
> Cplusplus-sig mailing list
> Cplusplus-sig at python.org
> https://mail.python.org/mailman/listinfo/cplusplus-sig
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From matt.p.conte at gmail.com  Mon Aug  8 10:14:26 2016
From: matt.p.conte at gmail.com (Matthew Conte)
Date: Mon, 8 Aug 2016 10:14:26 -0400
Subject: [C++-sig] Cplusplus-sig Digest, Vol 94, Issue 2
In-Reply-To: <4D8730C2-DE71-45A7-8305-7B0157554E38@gmail.com>
References: <mailman.9.1470412802.3831.cplusplus-sig@python.org>
 <4D8730C2-DE71-45A7-8305-7B0157554E38@gmail.com>
Message-ID: <CAFwmYYi24SRgW52HpaV9-+TFPP33H3Yuw0bRpY8B-FbRqp6FgQ@mail.gmail.com>

Hi Alexandra,

Thanks for your input, unfortunately I still the get same error. I think
I'll follow Stefen's advice and instead use the Boost.Numpy ndarray wrapper
in place of numeric::array.

Thank you.

On Fri, Aug 5, 2016 at 11:37 AM, <foxtog at gmail.com> wrote:

> The problem doesn't have anything to do with boost.python. The thing is in
> initializing numpy API pointer specifically PyArray_API*. If you print this
> pointer before creating the array, it'll turn out to be null. If you move
> import_array function just before the array creation call, it should work.
> You can find more details here
> http://docs.scipy.org/doc/numpy/reference/c-api.array.html in
> Miscellaneous section at the bottom.
>
> Regards,
> Alexandra
>
> 05 ???. 2016 ?., ? 20:00, cplusplus-sig-request at python.org ???????(?):
>
> Send Cplusplus-sig mailing list submissions to
>    cplusplus-sig at python.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>    https://mail.python.org/mailman/listinfo/cplusplus-sig
> or, via email, send a message with subject or body 'help' to
>    cplusplus-sig-request at python.org
>
> You can reach the person managing the list at
>    cplusplus-sig-owner at python.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Cplusplus-sig digest..."
>
>
> Today's Topics:
>
>   1. Segmentation Fault (core dumped) on Python 3.5.2 but not
>      Python 2.7.12 (Matthew Conte)
>   2. Re: Segmentation Fault (core dumped) on Python 3.5.2 but not
>      Python 2.7.12 (Stefan Seefeld)
>   3. Re: Segmentation Fault (core dumped) on Python 3.5.2 but not
>      Python 2.7.12 (Matthew Conte)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 4 Aug 2016 13:10:23 -0400
> From: Matthew Conte <matt.p.conte at gmail.com>
> To: cplusplus-sig at python.org
> Subject: [C++-sig] Segmentation Fault (core dumped) on Python 3.5.2
>    but not Python 2.7.12
> Message-ID:
>    <CAFwmYYjxXXVQV=6Wv8x_q4Uc2GjogR1OR_JSURhP3kCMrEb-gQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> So I'm trying to create a boost python module that simply creates and
> returns a numpy array,
> but the function crashes (sometimes) and it doesn't ever seem to crash on
> Python 2.
>
> Here's the source code I made:
>
> #include <boost/python.hpp>
> #include <numpy/ndarrayobject.h>
>
> using namespace boost::python;
>
> object create_numpy_array() {
> npy_intp dims = 1;
> long* data = new long[1];
> data[0] = 1;
> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR, data);
> boost::python::handle<> handle(obj);
> boost::python::numeric::array arr(handle);
> return arr.copy();
> }
>
> BOOST_PYTHON_MODULE(create) {
> import_array();
> numeric::array::set_module_and_type("numpy", "ndarray");
> def("numpy_array", &create_numpy_array);
> }
>
>
> using a simple python script to test:
>
> import create
> print(create.numpy_array())
>
>
> The stack trace indicates that the crash occurs on a boost::python::handle
> destructor trying to decrease the ref count of a PyObject with a ref count
> of 0.
>
> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
>
> Thank you.
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <http://mail.python.org/pipermail/cplusplus-sig/
> attachments/20160804/2ad0a9ec/attachment-0001.html>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 4 Aug 2016 13:14:58 -0400
> From: Stefan Seefeld <stefan at seefeld.name>
> To: cplusplus-sig at python.org
> Subject: Re: [C++-sig] Segmentation Fault (core dumped) on Python
>    3.5.2 but not Python 2.7.12
> Message-ID: <32f9c08d-2d65-c1b5-ca1a-1055f3784240 at seefeld.name>
> Content-Type: text/plain; charset=windows-1252
>
> Hi Matthew,
>
> would you mind submitting an issue on
> https://github.com/boostorg/python/issues for this.
>
> Thanks,
>        Stefan
>
> On 04.08.2016 13:10, Matthew Conte wrote:
>
> So I'm trying to create a boost python module that simply creates and
>
> returns a numpy array,
>
> but the function crashes (sometimes) and it doesn't ever seem to crash
>
> on Python 2.
>
>
> Here's the source code I made:
>
>
> #include <boost/python.hpp>
>
> #include <numpy/ndarrayobject.h>
>
>
> using namespace boost::python;
>
>
> object create_numpy_array() {
>
> npy_intp dims = 1;
>
> long* data = new long[1];
>
> data[0] = 1;
>
> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR,
>
> data);
>
> boost::python::handle<> handle(obj);
>
> boost::python::numeric::array arr(handle);
>
> return arr.copy();
>
> }
>
>
> BOOST_PYTHON_MODULE(create) {
>
> import_array();
>
> numeric::array::set_module_and_type("numpy", "ndarray");
>
> def("numpy_array", &create_numpy_array);
>
> }
>
>
>
> using a simple python script to test:
>
>
> import create
>
> print(create.numpy_array())
>
>
>
> The stack trace indicates that the crash occurs on a
>
> boost::python::handle destructor trying to decrease the ref count of a
>
> PyObject with a ref count of 0.
>
>
> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
>
>
> Thank you.
>
>
>
> _______________________________________________
>
> Cplusplus-sig mailing list
>
> Cplusplus-sig at python.org
>
> https://mail.python.org/mailman/listinfo/cplusplus-sig
>
>
>
> --
>
>      ...ich hab' noch einen Koffer in Berlin...
>
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 4 Aug 2016 13:16:58 -0400
> From: Matthew Conte <matt.p.conte at gmail.com>
> To: "Development of Python/C++ integration" <cplusplus-sig at python.org>
> Subject: Re: [C++-sig] Segmentation Fault (core dumped) on Python
>    3.5.2 but not Python 2.7.12
> Message-ID:
>    <CAFwmYYjN4CDP4sLAs0C4JACFHPOxLeDyPX+LoSpv4NdGVfhGEQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> I will, thank you.
>
> On Thu, Aug 4, 2016 at 1:14 PM, Stefan Seefeld <stefan at seefeld.name>
> wrote:
>
> Hi Matthew,
>
>
> would you mind submitting an issue on
>
> https://github.com/boostorg/python/issues for this.
>
>
> Thanks,
>
>        Stefan
>
>
> On 04.08.2016 13:10, Matthew Conte wrote:
>
> So I'm trying to create a boost python module that simply creates and
>
> returns a numpy array,
>
> but the function crashes (sometimes) and it doesn't ever seem to crash
>
> on Python 2.
>
>
> Here's the source code I made:
>
>
> #include <boost/python.hpp>
>
> #include <numpy/ndarrayobject.h>
>
>
> using namespace boost::python;
>
>
> object create_numpy_array() {
>
> npy_intp dims = 1;
>
> long* data = new long[1];
>
> data[0] = 1;
>
> PyObject* obj = PyArray_SimpleNewFromData(1, &dims, PyArray_LONGLTR,
>
> data);
>
> boost::python::handle<> handle(obj);
>
> boost::python::numeric::array arr(handle);
>
> return arr.copy();
>
> }
>
>
> BOOST_PYTHON_MODULE(create) {
>
> import_array();
>
> numeric::array::set_module_and_type("numpy", "ndarray");
>
> def("numpy_array", &create_numpy_array);
>
> }
>
>
>
> using a simple python script to test:
>
>
> import create
>
> print(create.numpy_array())
>
>
>
> The stack trace indicates that the crash occurs on a
>
> boost::python::handle destructor trying to decrease the ref count of a
>
> PyObject with a ref count of 0.
>
>
> I've tried this on both Windows 7 and Ubuntu 16.04 both 64-bit.
>
>
> Thank you.
>
>
>
> _______________________________________________
>
> Cplusplus-sig mailing list
>
> Cplusplus-sig at python.org
>
> https://mail.python.org/mailman/listinfo/cplusplus-sig
>
>
>
> --
>
>
>      ...ich hab' noch einen Koffer in Berlin...
>
>
> _______________________________________________
>
> Cplusplus-sig mailing list
>
> Cplusplus-sig at python.org
>
> https://mail.python.org/mailman/listinfo/cplusplus-sig
>
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From wiskey5alpha at gmail.com  Thu Aug 25 09:17:43 2016
From: wiskey5alpha at gmail.com (Wiskey 5 Alpha)
Date: Thu, 25 Aug 2016 13:17:43 +0000
Subject: [C++-sig] Embedding and extending an application with python in c++
Message-ID: <CAE89rnxzg64uasmn0p5L3oRRZXZwQDhWDZ2J-1qTA8ZRjTsxjw@mail.gmail.com>

Hello,
I am trying to extend a C++ application using python as a scripting
language.  What I would like to do is :

* run the c++ application
* have the application iterate through a directory of python files
* each python file has access to variables/classes in the c++ application

I have listed the test program here :
http://stackoverflow.com/questions/39066307.  I am getting a core dump when
executing the test.

Any help would be appreciated.

- Tim
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