Boost Python包装的虚拟类 - 孩子返回​​错误：不匹配C++签名

Question

我有一个C++对象是虚拟类的孩子，我试图用python包装。该文件编译的，我可以将它导入蟒蛇，但是当我尝试调用的函数，我得到一个错误：

In [3]: x 
Out[3]: <beh.MappedBehaviourDomain at 0x23e7158> 

//So, obviously the constructor is working (or at least thinks it is) 

In [4]: x.subject_count() 
--------------------------------------------------------------------------- 
ArgumentError        Traceback (most recent call last) 
/home/max/verk/btr-email/build/x86_64/bin/ipython in <module>() 
----> 1 x.subject_count() 

ArgumentError: Python argument types in 
    BehaviourDomainWrap.subject_count(MappedBehaviourDomain) 
did not match C++ signature: 
    subject_count(BehaviourDomainWrap {lvalue}) 
    subject_count(BehaviourDomainWrap {lvalue}) 

我有一个很难理解这个错误信息;这是我第一次使用boost python，并且我没有太多的C++经验。以下是相关的代码：

// Instantiating class for use in boost python 
struct BehaviourDomainWrap : BehaviourDomain, wrapper<BehaviourDomain> 
{ 
    size_t subjectCount() const { 
     return this->get_override("subjectCount")(); 
    // A bunch of other methods removed 
} 


BOOST_PYTHON_MODULE(beh) { 

    class_<BehaviourDomainWrap, boost::noncopyable>("BehaviourDomainWrap") 
     .def("subject_count", pure_virtual(& BehaviourDomainWrap::subjectCount)) 
    ; 

    class_<MappedBehaviourDomain, bases<BehaviourDomainWrap> > 
     ("MappedBehaviourDomain", init<std::string>()) 
    ; 
} 

怎么回事，为什么？

Answer 1

我传递的是对象的包装版本而不是基础。我应该有：

class_<BehaviourDomainWrap, boost::noncopyable>("beh") 
    .def("subject_count", pure_virtual(& BehaviourDomain::subjectCount)) 
; 

class_<MappedBehaviourDomain, bases<BehaviourDomain> > 
    ("mapped_beh", init<std::string>()) 
;