Pybind - 奇怪的重复模板

Question

我有以下Class结构（我实际实现的简化示例）：

/* TestClass.hpp */
#pragma once

template <class Impl>
class CurRecTemplate {
protected:
    CurRecTemplate() {}
    ~CurRecTemplate() {}

    Impl& impl() { return static_cast<Impl&>(*this); }
    const Impl& impl() const { return static_cast<const Impl&>(*this); }
};

template <class Impl>
class BaseClass : public CurRecTemplate<Impl> {
public:
    BaseClass() { };

    template <class FuncType>
    double eval(const FuncType& func, double x) const
    {
        return this->impl().evalImplementation(func, x);
    }
};

class DerivedClass : public BaseClass<DerivedClass> {
public:
    template <class FuncType>
    double evalImplementation(const FuncType& f, double x) const
    {
        return f(x);
    };
};

然后

/* Source.cpp */
#include <pybind11/pybind11.h>
#include "TestClass.hpp"

namespace py = pybind11;

template<typename Impl>
void declare(py::module &m, const std::string& className) {
    using DeclareClass = BaseClass<Impl>;

    py::class_<DeclareClass, std::shared_ptr<DeclareClass>>(m, className.c_str())
        .def(py::init<>())
        .def("eval", &DeclareClass::eval);
}

PYBIND11_MODULE(PyBindTester, m) {
    declare<DerivedClass>(m, "DerivedClass");
}

我大致基于这个问题的答案。但是我得到的错误是：

C2783 'pybind11::class_> &pybind11::class_>::def(const char *,Func &&,const Extra &...)': could not deduce template argument for 'Func' ...\source.cpp 10
C2672 'pybind11::class_>::def': no matching overloaded function found ...\source.cpp 12

这似乎与第二个 template <class FuncType> 有关，我无法在任何地方定义它，因为通用函数 func 将在稍后传入。有什么办法可以规避这个问题吗？

Answer 1

eval 必须是接受 double 和 returns double（或可转换为 double 的类型）的函数，因此您可以使用 &DeclareClass::eval<double(*)(double)> 专门化模板；或更好地包括 <functional> 和 <pybind11/functional.h>，您可以完全删除模板并使 eval 将 std::function<double(double)> 作为其第一个参数。

更具体地说，我会改写如下

/* TestClass.hpp */
#pragma once
#include <functional>

template <class Impl>
class CurRecTemplate {
protected:
    CurRecTemplate() {}
    ~CurRecTemplate() {}

    Impl& impl() { return static_cast<Impl&>(*this); }
    const Impl& impl() const { return static_cast<const Impl&>(*this); }
};

template <class Impl>
class BaseClass : public CurRecTemplate<Impl> {
public:
    BaseClass() { };

    double eval(std::function<double(double)> func, double x) const
    {
        return this->impl().evalImplementation(func, x);
    }
};

class DerivedClass : public BaseClass<DerivedClass> {
public:
    double evalImplementation(std::function<double(double)> f, double x) const
    {
        return f(x);
    };
}; 

/* Source.cpp */
#include <pybind11/pybind11.h>
#include "TestClass.hpp"
#include <pybind11/functional.h>

namespace py = pybind11;

template<typename Impl>
void declare(py::module &m, const std::string& className) {
    using DeclareClass = BaseClass<Impl>;

    py::class_<DeclareClass, std::shared_ptr<DeclareClass>>(m, className.c_str())
        .def(py::init<>())
        .def("eval", &DeclareClass::eval);
}

PYBIND11_MODULE(Project1, m) {
    declare<DerivedClass>(m, "DerivedClass");
}

Pybind - 奇怪的重复模板

Pybind - Curiously Recurring Template

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