如何在 module.reload(） 之后保持 py::objects 存活

How to keep py::objects alive after module.reload()

本文关键字：py 之后 objects 存活 module reload      更新时间：2023-10-16

重新加载模块后my_module其所有对象都将被删除，但我想从C++中删除对象。如何防止Python删除对象？

#include <iostream>
#include <pybind11/embed.h>
class Obj{ ~Obj(){std::cout << "deleted" << std::endl;} };
PYBIND11_EMBEDDED_MODULE(module_obj, m) {
py::class_<Obj>(m,"Obj");
}
/*
#my_module.py
import module_obj
o = module_obj.Obj()
*/
py::scoped_interpreter intpr;
auto my_module = py::module::import("my_module")
auto* o = my_module.attr("o").cast<Obj*>()
my_module.reload() // now o is deleted, how to prevent it?

您需要将对象的引用计数保持在零以上o。最简单的方法是在C++端进行py::object(或者，等效地在python端创建一个对象(

#include <iostream>
#include <pybind11/embed.h>
namespace py=pybind11;
class Obj {
public:
~Obj() {
std::cout << "deleted" << std::endl;
}
};
PYBIND11_EMBEDDED_MODULE(my_module, m) {
py::class_<Obj>(m, "Cat")
.def(py::init());
}
int main() {
py::scoped_interpreter intpr;
std::cout << "Loading... " << std::endl;
auto my_module = py::module::import("my_module");
std::cout << "Load complete. " << std::endl;
py::object o = my_module.attr("Cat")(); // create new cat, automatically increases/decreases ref count 
std::cout << "Reloading... " << std::endl;
my_module.reload(); // now o is deleted, how to prevent it?
std::cout << "Reload complete. " << std::endl;
}

输出：

Loading... 
Load complete. 
Reloading... 
Reload complete. 
deleted
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