[shiboken2] Shared pointer support

adev

I want to wrap a library which is based on QT and which uses shared pointers. I stumbled over a few issues, one of them seems to be a showstopper:

It seems that wrapping classes which return shared pointers in a virtual method is not possible at all. Non-virtual functions are fine. The error from shiboken2 is "#error: CppGenerator::writeVirtualMethodNative: B::genA(): Could not find a minimal constructor for type 'QSharedPointer<A >'. This will result in a compilation error.".
I'm not sure about what can be expected from the shared pointer bridging. While I'm able to pass shared pointers which are generated from the c++ side around in python, it seems to be impossible to create a shared pointer from an object generated from the python side.
The documentation in shiboken regarding smart pointers seems to be very limited. I couldn't figure out if setting "ref-count-method" is required and why? For QSharedPointer, there doesn't seem to exist a method for querying the reference count.

The first point looks like a shiboken2 bug to me and I'm wondering if there are any workarounds here?

Here are my test files:

test.h

#ifndef TEST_H
#define TEST_H

#include <QtCore/QSharedPointer>

// if uncommented, you will get the following error when calling shiboken
// #error:  CppGenerator::writeVirtualMethodNative: B::genA(): Could not find a minimal constructor for type 'QSharedPointer<A >'. This will result in a compilation error.
#define SHIBOKEN_ERROR

class A
{
    public:
        int a;
        A(int _a);
        virtual ~A();
};

class B
{
    public:
        int b;
        B(int _b);
        virtual ~B();
        void doSomething(QSharedPointer<A> a);
        #ifdef SHIBOKEN_ERROR
        virtual
        #endif
        QSharedPointer<A> genA();
};

#endif

ptest.xml

<!--?xml version="1.0"?-->
<typesystem package="ptest">
    <load-typesystem name="typesystem_core.xml" generate="no" />

    <smart-pointer-type name="QSharedPointer" type="shared" getter="data" />

    <object-type name="A" />
    <object-type name="B" />
</typesystem>

ptest .py

import PySide2
import ptest

a=ptest.A(1)
b=ptest.B(2)

a2=b.genA()
print(a2.a)
b.doSomething(a2)

# following is not working, need to create a shared pointer from the python object a
b.doSomething(a)

SGaist

Hi and welcome to devnet,

Since it's on the shiboken level, I would recommend bringing your question to the PySide mailing list. You'll find there PySide2 developers/maintainers. This forum is more user oriented.

adev

Thanks for answering - I did so :)