在C++中使用pybind11将Python类表示为std::variant的类型
在C++中使用pybind11将Python类表示为std::variant的类型
提问于 2020-12-11 12:24:06
下面的工作示例将由int64_t和float组成的变量类型的向量返回给Python。其意图(由注释的代码行**所示)是通过允许在C++中构造的Decimal (python类)以相同的结构传递回Python，从而向其添加进一步的功能。
#include <pybind11/pybind11.h>
#include <vector>
#include <variant>
#include <string>
#include <pybind11/stl.h>
#include <pybind11/complex.h>
#include <pybind11/functional.h>
#include <pybind11/chrono.h>
namespace py = pybind11;
// Importing Decimal class, as shown here
// https://pybind11.readthedocs.io/en/stable/advanced/pycpp/object.html?highlight=Decimal(#accessing-python-libraries-from-c
py::object Decimal = py::module_::import("decimal").attr("Decimal");
//typedef std::variant<float, int64_t, Decimal> Listtypes; // **
typedef std::variant<float, int64_t> Listtypes;
std::vector<ListTypes> returnList() {
std::vector<ListTypes> list(3);
int64_t integerVal = 987654321;
float floatVal = 1.01;
// Constructing python object, as shown here
//https://pybind11.readthedocs.io/en/stable/advanced/pycpp/object.html#callingpythonfunctions
py::object pi = Decimal("3.14159");
list[0] = integerVal;
list[1] = floatVal;
//list[2] = pi; // **
return list;
}
PYBIND11_MODULE(pBind, m) {
m.def("returnList", &returnList, "Function to return list of differing types");
}因此，是否可以将Decimal表示为std::variant的一部分，以便将其传递回带有向量的Python，或者解决方案不那么简单？
回答 1
Stack Overflow用户
回答已采纳
发布于 2020-12-14 20:25:36
您不能只将pi变量添加到std::variant向量中，因为它的类型是py::object。您可以将它添加到您的ListTypes中，因此只需更改行
typedef std::variant<float, int64_t, py::object> Listtypes;
但是您在Python端的列表将是[987654321, 1.0099999904632568, Decimal(3.14159)]。
我认为您宁愿使用潘丁提供的铸件来转换pi变量来浮动，这样您的代码就会变成
#include <pybind11/pybind11.h>
#include <vector>
#include <variant>
#include <string>
#include <pybind11/stl.h>
#include <pybind11/complex.h>
#include <pybind11/functional.h>
#include <pybind11/chrono.h>
namespace py = pybind11;
// Importing Decimal class, as shown here
// https://pybind11.readthedocs.io/en/stable/advanced/pycpp/object.html?highlight=Decimal(#accessing-python-libraries-from-c
py::object Decimal = py::module_::import("decimal").attr("Decimal");
//typedef std::variant<float, int64_t, Decimal> Listtypes; // **
typedef std::variant<float, int64_t> Listtypes;
std::vector<ListTypes> returnList() {
std::vector<ListTypes> list(3);
int64_t integerVal = 987654321;
float floatVal = 1.01;
// Constructing python object, as shown here
//https://pybind11.readthedocs.io/en/stable/advanced/pycpp/object.html#callingpythonfunctions
py::object pi = Decimal("3.14159");
list[0] = integerVal;
list[1] = floatVal;
list[2] = pi.cast<float>(); // we cast to float
return list;
}
PYBIND11_MODULE(pBind, m) {
m.def("returnList", &returnList, "Function to return list of differing types");
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/65251326
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