[PySide] Shiboken not generating right code for member pointers?

[John Cummings]

On 10/22/2012 09:19 AM, Luiz Vitor Martinez Cardoso wrote:
> Anyone?
>
> On Sun, Oct 14, 2012 at 3:54 PM, Luiz Vitor Martinez Cardoso 
> <grabber at gmail.com <mailto:grabber at gmail.com>> wrote:
>
>     Dear,
>
>     I'm new to PySide/Shiboken but I'm enjoying it!
>
>     To be honest I don't like the lack of good and reasonable documentation
>     and examples.
>
>     I decided to create a git repo
>     (https://github.com/Grabber/shiboken-binding-examples) together my friend
>     /Yann Lanthony /to archive all the solutions we get to work in our lab. At
>     the end we plan to write a very detailed and extensive article including
>     everything from the installation (Win, OSX and Linux) to the binding
>     process itself.
>
>     Today the master's help to solve a little trouble.
>
>     I'm trying to wrap the following code:
>
>         class LIBFOO_EXPORT CustomType
>         {
>
>         public:
>                 CustomType() {}
>                 virtual ~CustomType() {}
>                 CustomType(const CustomType&) {}
>                 int a;
>                 int * b;
>         };
>
>
>     Using the following TypeSystem:
>
>         <?xml version="1.0"?>
>         <typesystem package="foo">
>         <primitive-type name="int"/>
>         <load-typesystem name="typesystem_core.xml" generate="no"/>
>         <object-type name="CustomType" />
>         </typesystem> 
>
>
>     But I'm getting some pointers erros in the generated wrapping code:
>
>         /home/lmvc/Projects/shiboken-binding-examples/build/foo/foo/customtype_wrapper.cpp:
>         In function 'PyObject* Sbk_CustomType_get_b(PyObject*, void*)':
>         /home/lmvc/Projects/shiboken-binding-examples/build/foo/foo/customtype_wrapper.cpp:166:33:
>         error: invalid conversion from 'int*' to 'int' [-fpermissive]
>         /home/lmvc/Projects/shiboken-binding-examples/build/foo/foo/customtype_wrapper.cpp:
>         In function 'int Sbk_CustomType_set_b(PyObject*, PyObject*, void*)':
>         /home/lmvc/Projects/shiboken-binding-examples/build/foo/foo/customtype_wrapper.cpp:187:33:
>         error: invalid conversion from 'int*' to 'int' [-fpermissive]
>         /home/lmvc/Projects/shiboken-binding-examples/build/foo/foo/customtype_wrapper.cpp:189:18:
>         error: invalid conversion from 'int' to 'int*' [-fpermissive]
>         make[2]: *** [foo/CMakeFiles/foo.dir/foo/customtype_wrapper.cpp.o] Error 1
>
>
>
>     The generated wrapping code was:
>
>         static PyObject* Sbk_CustomType_get_b(PyObject* self, void*)
>         {
>             ::CustomType* cppSelf = 0;
>             SBK_UNUSED(cppSelf)
>             if (!Shiboken::Object::isValid(self))
>                 return 0;
>             cppSelf =
>         ((::CustomType*)Shiboken::Conversions::cppPointer(SbkfooTypes[SBK_CUSTOMTYPE_IDX],
>         (SbkObject*)self));
>             int cppOut_local = cppSelf->b;
>             PyObject* pyOut =
>         Shiboken::Conversions::copyToPython(Shiboken::Conversions::PrimitiveTypeConverter<int>(),
>         &cppOut_local);
>             return pyOut;
>         }
>         static int Sbk_CustomType_set_b(PyObject* self, PyObject* pyIn, void*)
>         {
>             ::CustomType* cppSelf = 0;
>             SBK_UNUSED(cppSelf)
>             if (!Shiboken::Object::isValid(self))
>                 return 0;
>             cppSelf =
>         ((::CustomType*)Shiboken::Conversions::cppPointer(SbkfooTypes[SBK_CUSTOMTYPE_IDX],
>         (SbkObject*)self));
>             if (pyIn == 0) {
>                 PyErr_SetString(PyExc_TypeError, "'b' may not be deleted");
>                 return -1;
>             }
>             PythonToCppFunc pythonToCpp;
>             if (!(pythonToCpp =
>         Shiboken::Conversions::isPythonToCppConvertible(Shiboken::Conversions::PrimitiveTypeConverter<int>(),
>         (pyIn)))) {
>                 PyErr_SetString(PyExc_TypeError, "wrong type attributed to
>         'b', 'int' or convertible type expected");
>                 return -1;
>             }
>             int cppOut_local = cppSelf->b;
>             pythonToCpp(pyIn, &cppOut_local);
>             cppSelf->b = cppOut_local;
>             return 0;
>         }
>
>
>
>     Could someone tell me what is going on? I feel I have to inject some code
>     in TypeSystem but I don't know well...
>
>     I appreciate your help!
>     Best regards,
>     Luiz Vitor.
>

Luiz,

I'm not certain, but since no one else jumped in, I believe it relates to int 
being a primitive type. That is, it maps the types directly instead of using an 
opaque pointer. I seem to recall there being similar issues [1] for me when I 
tried to have a member array of primitives (which in C/C++ can be thought of as 
a glorified pointer). The summary of the answer had to do with not being able to 
keep track of updates to the pointer, or something like that.

I believe types specified as "value-type" are similar in that they are passed by 
value.

Perhaps someone more knowledgeable can correct my simplistic answers.

Hope that helps
John Cummings

[1] http://thread.gmane.org/gmane.comp.lib.qt.pyside/2331/focus=2332
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