Dear all,
first of all thanks to Holger for pointing me to a workaround with the
add_static_property problem!
Unfortunately, I already ran into the next problem, which seems very weird to
me:
I have again my old friends Base and Derived, with the obvious inheritance
(source file attached). Now, there is a third class, named "Third", which has
as a data member a boost::shared_ptr<Base> which is initialized in the
constructor. For this reason, the constructor takes such a pointer as an
argument.
Now, the point where stuff goes wrong is this: the argument to the constructor
has as a default value a NULL-boost::shared_ptr<Base>. The behavior now works
as expected if the argument is provided in python:
>>> import testInheritance
>>> t = testInheritance.Third(testInheritance.Derived())
>>> t.get_base().name()
'Derived'
>>>
However, this fails if one does not provide an argument:
>>> t = testInheritance.Third()
>>> t.get_base().name()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
Boost.Python.ArgumentError: Python argument types in
Derived.name(Derived)
did not match C++ signature:
name(DerivedWrapper {lvalue})
name(DerivedWrapper {lvalue})
>>>
I cannot wrap my head around this, can anybody point me to what I am doing
wrong? I would be very grateful!
Best regards,
Karl Bicker
#include<boost/python.hpp>
#include<massDependence.h>
namespace bp = boost::python;
struct Base {
Base() { };
virtual ~Base() { };
virtual double do_stuff(double input) = 0;
virtual std::string name() const { return "Base"; };
};
struct BaseWrapper : public Base,
bp::wrapper<Base>
{
BaseWrapper() :
Base(),
bp::wrapper<Base>() { };
BaseWrapper(const Base& base) :
Base(base),
bp::wrapper<Base>() { };
double do_stuff(double input) {
return this->get_override("do_stuff")(input);
};
std::string name() const {
if(bp::override name = this->get_override("name")) {
return name();
}
return Base::name();
};
std::string default_name() const {
return Base::name();
};
};
struct Derived : public Base
{
Derived() : Base() { };
virtual ~Derived() { };
virtual double do_stuff(double input) { return (2. * input); };
virtual std::string name() const { return "Derived"; };
};
struct DerivedWrapper : public Derived,
bp::wrapper<Derived>
{
DerivedWrapper() :
Derived(),
bp::wrapper<Derived>() { };
DerivedWrapper(const Derived& derived) :
Derived(derived),
bp::wrapper<Derived>() { };
double do_stuff(double input) {
if(bp::override do_stuff = this->get_override("do_stuff")) {
return do_stuff(input);
}
return Derived::do_stuff(input);
};
double default_do_stuff(double input) {
return Derived::do_stuff(input);
};
std::string name() const {
if(bp::override name = this->get_override("name")) {
return name();
}
return Derived::name();
};
std::string default_name() const {
return Derived::name();
};
};
struct Third
{
Third(const boost::shared_ptr<Base>& base = boost::shared_ptr<Base>())
: _base(base)
{
if(not _base) {
_base = boost::shared_ptr<Base>(new Derived());
}
};
Third(const Third& third) {
_base = third._base;
};
const boost::shared_ptr<Base>& get_base() const {
return _base;
};
private:
boost::shared_ptr<Base> _base;
};
struct ThirdWrapper : public Third, bp::wrapper<Third>
{
ThirdWrapper(const boost::shared_ptr<Base>& base = boost::shared_ptr<Base>())
: Third(base), bp::wrapper<Third>() { };
ThirdWrapper(const Third& third)
: Third(third), bp::wrapper<Third>() { };
};
BOOST_PYTHON_MODULE(testInheritance) {
bp::class_<BaseWrapper, boost::noncopyable>("Base", bp::no_init)
.def("do_stuff", bp::pure_virtual(&BaseWrapper::do_stuff))
.def("name", &BaseWrapper::name, &BaseWrapper::default_name);
bp::class_<DerivedWrapper, bp::bases<Base> >("Derived")
.def("do_stuff", &DerivedWrapper::do_stuff, &DerivedWrapper::default_do_stuff)
.def("name", &DerivedWrapper::name, &DerivedWrapper::default_name);
bp::class_<ThirdWrapper>("Third", bp::no_init)
.def(bp::init<bp::optional<boost::shared_ptr<Base> > >())
.def(
"get_base"
, &Third::get_base
, bp::return_value_policy<bp::copy_const_reference>()
);
bp::register_ptr_to_python<boost::shared_ptr<Base> >();
bp::register_ptr_to_python<boost::shared_ptr<Derived> >();
bp::register_ptr_to_python<boost::shared_ptr<Third> >();
}
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