I don't understand; all the enable_shared_from_this stuff is commented
out. Can you please post the complete, correct example that you tried?
on Mon Apr 23 2012, Holger Brandsmeier <brandsmeier-AT-gmx.de> wrote:
> Dave,
>
> Here is the reduced example with only the
> `boost::enable_shared_from_this` variant. The issues are all as
> reported before.
>
> -Holger
>
> On Mon, Apr 23, 2012 at 22:25, Dave Abrahams <d...@boostpro.com> wrote:
>>
>> on Mon Apr 23 2012, Holger Brandsmeier <brandsmeier-AT-gmx.de> wrote:
>>
>>> In fact the statement
>>> class_<IWrapper, boost::shared_ptr<IWrapper>, boost::noncopyable
>>>>("I", init<>() )
>>> has an issue. When I call getThisRCP() later, and the return value is
>>> not a null shared pointer, then I in fact the error
>>> TypeError: No to_python (by-value) converter found for C++ type:
>>> boost::shared_ptr<I>
>>> which is quite annoying. I also implemented Dave's suggestion with
>>> boost::enable_shared_from_this and because of the above issue I used
>>> this for the Wrapper and not the class itself (see K and KWrapper in
>>> the attachment).
>>>
>>> The behaviour of `enable_shared_from_this` is different from my
>>> initual getThisRCP() / setThisRCP() solution but still has seriour
>>> problems. Concider the code:
>>>
>>> class KDer(K):
>>> def __init__(self):
>>> K.__init__(self)
>>>
>>> k = KDer()
>>>
>>> In contrast to my initial solution the lines
>>> assert k.getThisRCP2() is not None
>>> k2 = k.getThisRCP2()
>>> now work, which is nice.
>>>
>>> Also this call works now:
>>> print k2.foo();
>>>
>>> However, the following two lines
>>> del k
>>> print k2.foo();
>>> give a segmentation fault. Note that the destructor for the class `K`
>>> has not been called, which would have printed a statement.
>>
>> Please post a reduced example without any of the "J" business that
>> illustrates exactly the problem you're having for this one particular
>> case. If doing so doesn't immediately reveal the problem to you, I'm
>> sure we can get to the bottom of it here.
>>
>>
>> --
>> Dave Abrahams
>> BoostPro Computing
>> http://www.boostpro.com
>>
>> _______________________________________________
>> Cplusplus-sig mailing list
>> Cplusplus-sig@python.org
>> http://mail.python.org/mailman/listinfo/cplusplus-sig
>
> from thisRCPPy import *
>
> print '\ntestcase for thisRCP as from python extended class (using
> enable_shared_from_this):'
> class KDer(K):
> def __init__(self):
> K.__init__(self)
>
> k = KDer()
> assert k.getThisRCP2() is not None
> k2 = k.getThisRCP2()
> if 1:
> print k2.foo();
> del k
> print 'with the `del k` statement the following statement will crash the
> program:';
> print k2.foo();
> print 'this line is never reached';
> #del k
> del k2
>
>
> #include <boost/python.hpp>
> #include "iostream"
> #include "string"
> #include "boost/weak_ptr.hpp"
> #include "boost/enable_shared_from_this.hpp"
>
> using namespace boost::python;
> using namespace std;
> //using Teuchos::RCP;
>
> struct K
> // : public boost::enable_shared_from_this<K>
> {
> virtual int foo() = 0;
>
> virtual ~K() {
> std::cout << "destructor for K called ..." << std::endl;
> }
>
> /*boost::shared_ptr<K> getThisRCP() {
> return shared_from_this();
> }*/
> };
>
> struct KWrapper : public K, public boost::python::wrapper<K>,
> public boost::enable_shared_from_this<KWrapper>
> {
>
> KWrapper() {
>
> }
>
> virtual int foo() {
> if( override f = this->get_override("foo") ) {
> return f();
> } else {
> return base_foo();
> }
> }
>
> boost::shared_ptr<KWrapper> getThisRCP2() {
> return shared_from_this();
> }
>
> int base_foo() {
> return 0;
> }
> };
>
> BOOST_PYTHON_MODULE(thisRCPPy)
> {
> {
> typedef K ClassT;
> class_<KWrapper, boost::shared_ptr<KWrapper>, boost::noncopyable >("K",
> init<>() )
> //.def("getThisRCP", &ClassT::getThisRCP)
> .def("getThisRCP2", &KWrapper::getThisRCP2)
> .def("foo", &ClassT::foo)
> ;
> }
> }
> _______________________________________________
> Cplusplus-sig mailing list
> Cplusplus-sig@python.org
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--
Dave Abrahams
BoostPro Computing
http://www.boostpro.com
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