How to cast self recursive data structure to python?

[jhonsonlaid]

I have a self-recursive data structure BVHNode, whose members contain BVHNode *, which is initialized as nullptr. But when the recursion depth >=1, it seems to lead to segmentation faults. (See python code print for details)

C++ Example code:

class BVHNode {
public:
    AABB aabb;
    xt::pyarray<int> tri_indices;
    int timestep;
    bool is_leaf;
    BVHNode* left;
    BVHNode* right;

    BVHNode(){
        aabb = AABB(xt::pyarray<float>(), xt::pyarray<float>());
        tri_indices = xt::pyarray<int>();
        timestep = -1;
        is_leaf = false;
        left = nullptr;
        right = nullptr;
    }
};


PYBIND11_MODULE(bvh, m) {
    xt::import_numpy();

    py::class_<BVHNode>(m, "BVHNode")
        .def_readonly("aabb", &BVHNode::aabb)
        .def_readonly("tri_indices", &BVHNode::tri_indices)
        .def_readonly("timestep", &BVHNode::timestep)
        .def_readonly("is_leaf", &BVHNode::is_leaf)
        .def_readonly("left", &BVHNode::left)
        .def_readonly("right", &BVHNode::right);
}

auto run(){
    
    BVHNode a;
    a.tri_indices = xt::pyarray<int>({ 1, 2, 3 });

    BVHNode b;
    b.tri_indices = xt::pyarray<int>({ 4, 5, 6 });

    BVHNode c;
    c.left = &a;

    return c;
}

Python code:

import bvh  # cpp module
def main():
    c = bvh.run()
    print(c.left.left)  # Error, print <bvh.BVHNode object xx>, which should be None
    print(c.right)  # Right, print None
    print(c.left.tri_indices) # raise Error.

[jhonsonlaid]

I'm sorry, it's my C++ code problem. Fix by below:

auto run(){
    BVHNode *a = new BVHNode();
    a->tri_indices = xt::pyarray<int>({ 1, 2, 3 });
    BVHNode *b = new BVHNode();
    b->tri_indices = xt::pyarray<int>({ 4, 5, 6 });

    BVHNode c;
    c.left = a;
    c.right = b;

    return c;
}