使用 Boost.Python 導出非默認可構造類

Question

如何使用 Boost.Python 導出非默認構造的 class？

這段代碼：

class EventHandle {
 public:
  EventHandle() = delete;
  EventHandle(boost::shared_ptr<EventManager> const& em): event_manager_(em) {}
  EventHandle(EventHandle const&) = delete;
  ~EventHandle();
  shared_ptr<EventManager> event_manager_;
}
class_<EventHandle, noncopyable,
  init<boost::shared_ptr<EventManager> const&>>("EventHandle")

給出以下錯誤：

/opt/local/include/boost/python/pointee.hpp: In instantiation of 'boost::python::detail::pointee_impl<false>::apply<boost::python::init<const boost::shared_ptr<EventManager>&> >':
/opt/local/include/boost/python/pointee.hpp:38:1:   instantiated from 'boost::python::pointee<boost::python::init<const boost::shared_ptr<EventManager>&> >'
/opt/local/include/boost/mpl/eval_if.hpp:38:31:   instantiated from 'boost::mpl::eval_if<boost::is_convertible<boost::python::init<const boost::shared_ptr<EventManager>&>*, EventHandle*>, boost::mpl::identity<boost::python::init<const boost::shared_ptr<EventManager>&> >, boost::python::pointee<boost::python::init<const boost::shared_ptr<EventManager>&> > >'
/opt/local/include/boost/python/object/class_metadata.hpp:179:13:   instantiated from 'boost::python::objects::class_metadata<EventHandle, boost::noncopyable_::noncopyable, boost::python::init<const boost::shared_ptr<EventManager>&>, boost::python::detail::not_specified>'
/opt/local/include/boost/python/class.hpp:174:42:   instantiated from 'boost::python::class_<EventHandle, boost::noncopyable_::noncopyable, boost::python::init<const boost::shared_ptr<EventManager>&> >::id_vector'
/opt/local/include/boost/python/class.hpp:627:55:   instantiated from 'boost::python::class_<T, X1, X2, X3>::class_(const char*, const char*) [with W = EventHandle, X1 = boost::noncopyable_::noncopyable, X2 = boost::python::init<const boost::shared_ptr<EventManager>&>, X3 = boost::python::detail::not_specified]'
/Users/neil/nn/src/core/python_event.cc:21:66:   instantiated from here
/opt/local/include/boost/python/pointee.hpp:28:44: error: no type named 'element_type' in 'class boost::python::init<const boost::shared_ptr<EventManager>&>'
make[3]: *** [CMakeFiles/distributions.dir/core/python_event.cc.o] Error 1
make[2]: *** [CMakeFiles/distributions.dir/all] Error 2
make[1]: *** [CMakeFiles/distributions.dir/rule] Error 2
make: *** [distributions] Error 2

Answer 1

您需要使用init<...>公開構造函數。 例如，對於采用兩個整數的構造函數：

class_<MyClass>("MyClass", init<int, int>())
    ....

請注意，您需要將init放在class_參數中，而不是放在單獨的.def()調用中，否則 Boost 會假設您有一個默認構造函數。

請參閱有關構造函數的教程部分。

編輯：對於您的代碼，請嘗試：

class_<EventHandle, noncopyable>("EventHandle", 
    init<boost::shared_ptr<EventManager> const&>())

Answer 2

您是否嘗試過使用no_ini t？ 文檔說這是在您不需要構造函數時使用的，但也許您可以將它與明確要求一個？

class_<EventHandle, noncopyable,
    init<boost::shared_ptr<EventManager> const&> >
    ("EventHandle", no_init)