我有一个不可复制的X
类型,我想公开一个创建它们的list
的函数:
#include <boost/python.hpp>
namespace py = boost::python;
struct X {
X(int i) : i(i) { }
X(const X& ) = delete;
X& operator=(X const&) = delete;
int i;
friend std::ostream& operator<<(std::ostream& os, X const& x) {
return os << "X(" << x.i << ")";
}
};
py::list get_xs(int n) {
py::list xs;
for (int i = 0; i < n; ++i) {
xs.append(X{i});
}
return xs;
}
BOOST_PYTHON_MODULE(Foo)
{
py::class_<X, boost::noncopyable>("X", py::init<int>())
.def(str(py::self))
.def(repr(py::self))
;
py::def("get_xs", get_xs);
}
这可以很好地编译,但是当我尝试使用它时,却使我感到恐惧:
>>> import Foo
>>> Foo.get_xs(10)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: No to_python (by-value) converter found for C++ type: X
该错误实际上是什么意思?我如何解决它?
最佳答案
noncopyable
似乎是问题所在。如果X
是可复制的,那么一切都很好。
如果X
必须为noncopyable
,则可以使用boost::shared_ptr
:
py::list get_xs(int n) {
py::list xs;
for (int i = 0; i < n; ++i) {
xs.append(boost::shared_ptr<X>(new X(i)));
}
return xs;
}
....
BOOST_PYTHON_MODULE(Foo)
{
py::class_<X, boost::shared_ptr<X>, boost::noncopyable>("X", py::init<int>())
...
...
py::register_ptr_to_python<boost::shared_ptr<X>>();
}