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[section boost/python/pointee.hpp]
[section Introduction]
<boost/python/pointee.hpp> introduces a traits metafunction `template pointee<T>` that can be used to extract the "pointed-to" type from the type of a pointer or smart pointer.
[endsect]
[section Class template `pointee`]
`pointee<T>` is used by the [link high_level_components.boost_python_class_hpp.class_template_class_t_bases_hel `class_<...>`] template to deduce the type being held when a pointer or smart pointer type is used as its HeldType argument.
``
namespace boost { namespace python
{
template <class T> struct pointee
{
typedef T::element_type type;
};
// specialization for pointers
template <T> struct pointee<T*>
{
typedef T type;
};
}
``
[endsect]
[section Examples]
Given a 3rd-party smart pointer type `smart_pointer<T>`, one might partially specialize `pointee<smart_pointer<T> >` so that it can be used as the HeldType for a class wrapper:
``
#include <boost/python/pointee.hpp>
#include <boost/python/class.hpp>
#include <third_party_lib.hpp>
namespace boost { namespace python
{
template <class T> struct pointee<smart_pointer<T> >
{
typedef T type;
};
}}
BOOST_PYTHON_MODULE(pointee_demo)
{
class_<third_party_class, smart_pointer<third_party_class> >("third_party_class")
.def(...)
...
;
}
``
[endsect]
[endsect]
|
