From jab at ecs.soton.ac.uk  Mon Feb  7 12:42:13 2011
From: jab at ecs.soton.ac.uk (Julian Bailey)
Date: Mon, 7 Feb 2011 11:42:13 +0000
Subject: [C++-sig] Import causes access violation
References: <853FC6B008030C479F8C5A0529576D0F80E00537@EXCHANGE4.ecs.soton.ac.uk>
Message-ID: <EMEW3|5b4ee49334262ada810f4440819a6879n16BgJ03jab|ecs.soton.ac.uk|853FC6B008030C479F8C5A0529576D0F80E00537@EXCHANGE4.ecs.soton.ac.uk>

Hi,
I am running through the basic examples on the boost website for embedding boost::python.
My code currently reads:

#include <iostream>
#include "./include/Python.h"
#include "./boost/python.hpp"

using namespace boost::python;
int    main(void)
{
       Py_Initialize();
       object main_module = import("__main__");
       object main_namespace = main_module.attr("__dict__");
       object ignored = exec("print Hello world",main_namespace);
       return 0;
}
The program links successfully and begins running, however an access violation occurs (NULL pointer) at the first line after "py_initialize();" when i call import("__main__");
Visual studio 2010s debugger says the exception occurs at:  line 74 in object_attributes.hpp:
inline object const_attribute_policies::get(object const& target, char const* key)
{
    return python::getattr(target, key);
}
Python was built using Visual studio 2010 so i had access to the python debug library. Boost is version 1.45 and was built using :
bjam --build-type=complete msvc stage --with-python

I am linking against:
boost_python-vc100-mt-gd-1_45.lib
and
boost_python-vc100-mt-gd-1_45.dll

I have looked for soutions on the internet and have found nothing right now. Can anyone help me?

note: i am building my application in MSVC 2010, this should work though shouldn't it?


Dr Julian Bailey
Electronic Systems & Devices,
School of Electronics and Computer Science,
University of Southampton,
Southampton,
SO17 1BJ,
United Kingdom.

Tel. +44 (0)2380 593545
email: jab at ecs.soton.ac.uk


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From jab at ecs.soton.ac.uk  Tue Feb  8 07:43:52 2011
From: jab at ecs.soton.ac.uk (Julian Bailey)
Date: Tue, 8 Feb 2011 06:43:52 +0000
Subject: [C++-sig] Import causes access violation
In-Reply-To: <EMEW3|5b4ee49334262ada810f4440819a6879n16BgJ03jab|ecs.soton.ac.uk|853FC6B008030C479F8C5A0529576D0F80E00537@EXCHANGE4.ecs.soton.ac.uk>
References: <853FC6B008030C479F8C5A0529576D0F80E00537@EXCHANGE4.ecs.soton.ac.uk>
	<EMEW3|5b4ee49334262ada810f4440819a6879n16BgJ03jab|ecs.soton.ac.uk|853FC6B008030C479F8C5A0529576D0F80E00537@EXCHANGE4.ecs.soton.ac.uk>
	<853FC6B008030C479F8C5A0529576D0F80E0105C@EXCHANGE4.ecs.soton.ac.uk>
Message-ID: <EMEW3|28cb29ea9d68a6fa65f925af202dc4f8n176iI03jab|ecs.soton.ac.uk|853FC6B008030C479F8C5A0529576D0F80E0105C@EXCHANGE4.ecs.soton.ac.uk>

Fixed, I think...., needed to define BOOST_DEBUG_PYTHON in the c++ pre-processor definitions

Now having a different problem...will get back to you guys if I still have problems

Dr Julian Bailey
Electronic Systems & Devices,
School of Electronics and Computer Science,
University of Southampton,
Southampton,
SO17 1BJ,
United Kingdom.

Tel. +44 (0)2380 593545
email: jab at ecs.soton.ac.uk

From: cplusplus-sig-bounces+jab=ecs.soton.ac.uk at python.org [mailto:cplusplus-sig-bounces+jab=ecs.soton.ac.uk at python.org] On Behalf Of Julian Bailey
Sent: 07 February 2011 11:42
To: cplusplus-sig at python.org
Subject: [C++-sig] Import causes access violation

Hi,
I am running through the basic examples on the boost website for embedding boost::python.
My code currently reads:

#include <iostream>
#include "./include/Python.h"
#include "./boost/python.hpp"

using namespace boost::python;
int    main(void)
{
       Py_Initialize();
       object main_module = import("__main__");
       object main_namespace = main_module.attr("__dict__");
       object ignored = exec("print Hello world",main_namespace);
       return 0;
}
The program links successfully and begins running, however an access violation occurs (NULL pointer) at the first line after "py_initialize();" when i call import("__main__");
Visual studio 2010s debugger says the exception occurs at:  line 74 in object_attributes.hpp:
inline object const_attribute_policies::get(object const& target, char const* key)
{
    return python::getattr(target, key);
}
Python was built using Visual studio 2010 so i had access to the python debug library. Boost is version 1.45 and was built using :
bjam --build-type=complete msvc stage --with-python

I am linking against:
boost_python-vc100-mt-gd-1_45.lib
and
boost_python-vc100-mt-gd-1_45.dll

I have looked for soutions on the internet and have found nothing right now. Can anyone help me?

note: i am building my application in MSVC 2010, this should work though shouldn't it?


Dr Julian Bailey
Electronic Systems & Devices,
School of Electronics and Computer Science,
University of Southampton,
Southampton,
SO17 1BJ,
United Kingdom.

Tel. +44 (0)2380 593545
email: jab at ecs.soton.ac.uk


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From michael_andronov at sd-kyber.com  Thu Feb 10 21:19:08 2011
From: michael_andronov at sd-kyber.com (Michael Andronov)
Date: Thu, 10 Feb 2011 15:19:08 -0500
Subject: [C++-sig] C++ derived from bp::dict
Message-ID: <AANLkTi=mxVNg1bTvucaoTRvwT8qqfzPhiVM2csaxsBj5@mail.gmail.com>

Hi,

Being a newbie to boost::python, I have a  question ( hopefully
simple), which failed to find the answer in mail logs:

let's say
a.  I have a  C++ class, derived from boost::python::dict ;
b.  I would like later to get access to myLong, and to the dictionary,
my class derived from.

Would mentioning the boost::python::dict as a base wtihin wrapping
section be enough to get access to dictionary?
(Something like...
"
....
class myd :boost::python::dict {
...
  public:
     unsigned long myLong;
}

BOOST_PYTHON_MODULE(mymod)
{
   using namespace boost::python;

   class_<myd, bases<dict> > ("mydict")
		         .def_readwrite("pd", &myd::pd);
   ...
}	

Thanks.

Michael.

From seefeld at sympatico.ca  Thu Feb 10 21:30:23 2011
From: seefeld at sympatico.ca (Stefan Seefeld)
Date: Thu, 10 Feb 2011 15:30:23 -0500
Subject: [C++-sig] C++ derived from bp::dict
In-Reply-To: <AANLkTi=mxVNg1bTvucaoTRvwT8qqfzPhiVM2csaxsBj5@mail.gmail.com>
References: <AANLkTi=mxVNg1bTvucaoTRvwT8qqfzPhiVM2csaxsBj5@mail.gmail.com>
Message-ID: <4D544ADF.6080101@sympatico.ca>

Hi Michael,

I strongly doubt that what you want is possible.

While class_<A> generates a Python type that wraps 'A', 
boost::python::dict itself is not built that way. Rather, it is a proxy 
to a Python dict object. Types defined via "class_<>" are added to a 
type registrar, which is inspected whenever a C++<->Python conversion is 
requested. I strongly doubt that the boost::python::object derivatives 
are themselves registered there.

Besides, Python has strong requirements concerning what types are 
allowed to derive from what base types (as far as the associated 
meta-classes are concerned), which I don't think are met by the above.


     Stefan

-- 

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


From michael_andronov at sd-kyber.com  Thu Feb 10 22:03:37 2011
From: michael_andronov at sd-kyber.com (Michael Andronov)
Date: Thu, 10 Feb 2011 16:03:37 -0500
Subject: [C++-sig] C++ derived from bp::dict
In-Reply-To: <4D544ADF.6080101@sympatico.ca>
References: <AANLkTi=mxVNg1bTvucaoTRvwT8qqfzPhiVM2csaxsBj5@mail.gmail.com>
	<4D544ADF.6080101@sympatico.ca>
Message-ID: <AANLkTi=OmC4z64fC6peynQ2ipN2Cpsx6LUKjn-5yzSS2@mail.gmail.com>

Thanks for a speedy reply!
Michael.

From ephelon at gmail.com  Wed Feb 16 04:12:15 2011
From: ephelon at gmail.com (James Emerton)
Date: Tue, 15 Feb 2011 19:12:15 -0800
Subject: [C++-sig] Boost.Python Metaclass
Message-ID: <FD1B60C3-2A49-4882-B128-3486B05DBF76@gmail.com>

Given a C++ class wrapped with Boost.Python:

class CPPClass {
  void test();
}

BOOST_PYTHON_MODULE(testmodule)
{
  class_<CPPClass>("CPPClass")
    .def("test", &CPPClass::test)
    ;
}

I've created a python subclass and redefined the metaclass:

class Meta(CPPClass.__class__):
  def __new__(cls, name, bases, attrs):
    return super(Meta, cls).__new__(cls, name, bases, attrs)

class PyClass(CPPClass):
  __metaclass__ = Meta


Any attempt to call methods of PyClass, or to pass it as an argument to a C++ function results in an ArgumentError.  It appears that ob_type is being tested for equivalence to the Boost.Python.class type.

I am currently working around this by using a plain function as the metaclass, but it's not ideal as each base class must set the metaclass explicitly.


I browsed through object/class.cpp, and I think using PyType_IsSubtype() in place of == &class_metatype_object should be sufficient to allow me to derive metaclasses from Boost.Python.class.  

Does anyone have any advice, comments or objections before I proceed? 

James


From rwgk at yahoo.com  Wed Feb 16 08:08:40 2011
From: rwgk at yahoo.com (Ralf W. Grosse-Kunstleve)
Date: Tue, 15 Feb 2011 23:08:40 -0800 (PST)
Subject: [C++-sig] Boost.Python Metaclass
In-Reply-To: <FD1B60C3-2A49-4882-B128-3486B05DBF76@gmail.com>
References: <FD1B60C3-2A49-4882-B128-3486B05DBF76@gmail.com>
Message-ID: <868446.79851.qm@web111403.mail.gq1.yahoo.com>

Hi James,

> I browsed through object/class.cpp, and I think using  PyType_IsSubtype()
> in place of == &class_metatype_object should be  sufficient to allow me
> to derive metaclasses from Boost.Python.class.  


Could (or did?) you try it out? Ideally based on the current boost svn
trunk. If you send me the patches I'll check them in after testing
locally. Could you try to fit your test example into one of the
existing files in libs/python/test?

Ralf

From wichert at wiggy.net  Mon Feb 21 11:36:52 2011
From: wichert at wiggy.net (Wichert Akkerman)
Date: Mon, 21 Feb 2011 11:36:52 +0100
Subject: [C++-sig] Creating a unicode instrance from utf-8 encoded string
Message-ID: <4D624044.70004@wiggy.net>

I'm trying to do something which should be very simple, but I'm not 
having much luck figuring out how from the existing documentation.

For a python 2 project I am trying to return a gettext-translated string 
as a unicode instance to python. The return value for gettext() is a 
UTF-8 encoded char*, which should be pretty simple to convert to a 
python unicode instrance using PyUnicode_FromString. I have a feeling 
this is trivial to do, but I can't seem to figure out how.

Wichert.


From hans_meine at gmx.net  Mon Feb 21 14:33:03 2011
From: hans_meine at gmx.net (Hans Meine)
Date: Mon, 21 Feb 2011 14:33:03 +0100
Subject: [C++-sig] Creating a unicode instrance from utf-8 encoded string
In-Reply-To: <4D624044.70004@wiggy.net>
References: <4D624044.70004@wiggy.net>
Message-ID: <201102211433.03756.hans_meine@gmx.net>

Am Montag, 21. Februar 2011, um 11:36:52 schrieb Wichert Akkerman:
> I'm trying to do something which should be very simple, but I'm not
> having much luck figuring out how from the existing documentation.
> 
> For a python 2 project I am trying to return a gettext-translated string
> as a unicode instance to python. The return value for gettext() is a
> UTF-8 encoded char*, which should be pretty simple to convert to a
> python unicode instrance using PyUnicode_FromString. I have a feeling
> this is trivial to do, but I can't seem to figure out how.

According to http://docs.python.org/c-api/unicode.html , this is exactly what 
PyUnicode_FromString is supposed to do.

What's the problem?  Do you get an error?  Some code might help.

HTH,
  Hans

From wichert at wiggy.net  Mon Feb 21 14:35:42 2011
From: wichert at wiggy.net (Wichert Akkerman)
Date: Mon, 21 Feb 2011 14:35:42 +0100
Subject: [C++-sig] Creating a unicode instrance from utf-8 encoded string
In-Reply-To: <201102211433.03756.hans_meine@gmx.net>
References: <4D624044.70004@wiggy.net> <201102211433.03756.hans_meine@gmx.net>
Message-ID: <4D626A2E.9080102@wiggy.net>

On 2/21/11 14:33 , Hans Meine wrote:
> Am Montag, 21. Februar 2011, um 11:36:52 schrieb Wichert Akkerman:
>> I'm trying to do something which should be very simple, but I'm not
>> having much luck figuring out how from the existing documentation.
>>
>> For a python 2 project I am trying to return a gettext-translated string
>> as a unicode instance to python. The return value for gettext() is a
>> UTF-8 encoded char*, which should be pretty simple to convert to a
>> python unicode instrance using PyUnicode_FromString. I have a feeling
>> this is trivial to do, but I can't seem to figure out how.
>
> According to http://docs.python.org/c-api/unicode.html , this is exactly what
> PyUnicode_FromString is supposed to do.
>
> What's the problem?  Do you get an error?  Some code might help.

For a single unicode instance this is indeed working correctly. 
Unfortunately it breaks down when I need to return a list of unicode 
instances. My simple approach looks like this:

boost::python::list PyMyFunc() {
     std::vector<std::string> raw_strings = BaseClass::MyFunc();
     std::vector<std::string>::const_iterator i;
     boost::python::list result;

     for (i=raw_strings.begin(); i!=raw_strings.end(); i++)
         result.append(PyUnicode_FromString(i->c_str()));
     return result;
}

but that results in a lot of compile errors suggesting that bp::list 
does not know how to handle PyObject* values.

Wichert.

From rwgk at yahoo.com  Mon Feb 21 17:29:29 2011
From: rwgk at yahoo.com (Ralf W. Grosse-Kunstleve)
Date: Mon, 21 Feb 2011 08:29:29 -0800 (PST)
Subject: [C++-sig] Creating a unicode instrance from utf-8 encoded string
In-Reply-To: <4D626A2E.9080102@wiggy.net>
References: <4D624044.70004@wiggy.net> <201102211433.03756.hans_meine@gmx.net>
	<4D626A2E.9080102@wiggy.net>
Message-ID: <457487.11242.qm@web111412.mail.gq1.yahoo.com>

>          result.append(PyUnicode_FromString(i->c_str()));


try

result.append(object(handle<>(PyUnicode_FromString(i->c_str()))));

The handle<> is a way to tell Boost.Python if you own the reference or if it is 
borrowed (among other things). The
suggested code assumes you own the reference.

Ralf

From ndbecker2 at gmail.com  Tue Feb 22 16:30:12 2011
From: ndbecker2 at gmail.com (Neal Becker)
Date: Tue, 22 Feb 2011 10:30:12 -0500
Subject: [C++-sig] Can't add attribute to function
Message-ID: <ik0kq5$osr$1@dough.gmane.org>

I can add attributes to instances of classes created by boost::python, but not 
to boost::python functions:

    limiter.delay = 0
AttributeError: 'Boost.Python.function' object has no attribute 'delay'

Any ideas?


From adrian.baetu at plato-ag.com  Wed Feb 23 12:27:25 2011
From: adrian.baetu at plato-ag.com (AdrianB)
Date: Wed, 23 Feb 2011 11:27:25 +0000 (UTC)
Subject: [C++-sig] init< LPCTSTR > error if used in static member of same
	class
Message-ID: <loom.20110223T122251-552@post.gmane.org>

Anny Idea why following situation failes to compile?

class A
{
public:
	A( LPCTSTR szParam ){};
	~A(){};
};

class B: public A
{
public:
	B( LPCTSTR szParam ) A(szParam){};
	~B(){};

	static void includePyModuleDefinition();
};

void B::includePyModuleDefinition()
{
	class_<B>("MyB", init< LPCTSTR >() );
}

Compiler result is:
error C2275: 'LPCTSTR' : illegal use of this type as an expression
  c:\program files\microsoft sdks\windows\v6.0a\include\winnt.h(391) : 
                                             see declaration of 'LPCTSTR'
error C2059: syntax error : ')'

The eonly way to solve this issue by now are:
- use no_init => not an option for me because I need the parameter
- move the static member function out of the class B => unhappy because this
would be a breach of my codeing std. for this module 
- remove the class inheritance for B to 'public A'

The problem arises only if following three facts come togather:
1) inheritance  from a base class
2) the includePyModuleDefinition() is a static member of the exposed class 
   iteself
3) the init has to tale at least one param


Regards,
Adrian


From rogeeff at gmail.com  Sun Feb 27 08:54:57 2011
From: rogeeff at gmail.com (Gennadiy Rozental)
Date: Sun, 27 Feb 2011 07:54:57 +0000 (UTC)
Subject: [C++-sig] intercepting uncaught exceptions
Message-ID: <loom.20110227T085145-392@post.gmane.org>

Hi,

Is there any way to intercept uncaught exception in embedded Python code?

I need to add some information to an exception/traceback in this case. I have
full control over environment before embedded code is executed.

I thought I'll be able to use sys.excepthook, but it does not seem to be invoked.

Please advise,

Gennadiy