On Thu, Jun 25, 2009 at 6:31 AM, Nicolas Lara<nicolasl...@gmail.com> wrote:
> Hello,
>
> I'm having trouble trying to override a method on a class exposed to
> Python. I cannot modify the original class, so I need to wrap it to
> change the behaviour of some methods to be Python compatible. The
> classes look like the following:
>
> struct DocumentWrap : Document, wrapper<Document>
> {
> DocumentWrap() : Document(){ };
> DocumentWrap(const Document&) { };
> wstring toString()
> {
> wstring w(_T("test"));
> return w;
> }
> int test(){
> return 1;
> }
> };
>
> class_<Hits>("Hits", init<int>())
> .def("doc", &Hits::doc, return_internal_reference<>());
> class_<DocumentWrap>("Document")
> .def("toString", &DocumentWrap::toString)
> .def("test", &DocumentWrap::test)
> ;
>
> Hits::doc returns a Document. If I do:
>
>>>> d = Document()
>>>> d.test()
> 1
>>>> d.toString()
> "test"
>
> I get the right answer. However, If I obtain the class through Hits I
> get a reference to a c++ object of type Document (not DocumentWrap) so
> trying to execute the methods yield:
>
> Traceback (most recent call last):
> File "t.py", line 10, in <module>
> d.test()
> Boost.Python.ArgumentError: Python argument types in
> Document.test(Document)
> did not match C++ signature:
> test(DocumentWrap {lvalue})
>
> Traceback (most recent call last):
> File "t.py", line 10, in <module>
> d.toString()
> Boost.Python.ArgumentError: Python argument types in
> Document.toString(Document)
> did not match C++ signature:
> toString(DocumentWrap {lvalue})
>
> Is there any way to get python to understand the internal reference to
> Document can be treated as a DocumentWrap?
I don't think so. What you ask doesn't make sense.
The better solution would be to replace problematic function in another way:
struct Doc{
xyz** do_smth();
};
add new global function:
boost::python::list do_smth4py( Doc& d){
///call your function
}
and register it instead of the original function
class_< Doc>(...)
.def( "do_smth", &::do_smth4py )
The Python user will not note the difference.
HTH
--
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/
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