无法在 pybind11 中绑定重载的静态成员函数

Question

我尝试用 pybind11 绑定静态重载函数，但遇到了一些问题。

这里是示例代码

#include <pybind11/pybind11.h>

namespace py = pybind11;

class TESTDB {
  public:
    static void aaaa(int a, int b) {printf("aaaaa");};
    static void aaaa(int a) {printf("xxxxx");};
};

PYBIND11_MODULE(example, m) {


  py::class_<TESTDB>(m, "db")
     .def_static("aaaa", (void (TESTDB::*)(int, int)) &TESTDB::aaaa);

}

但是由于

编译失败

error: no matches converting function ‘aaaa’ to type ‘void (class TESTDB::*)(int, int)’
   .def_static("aaaa", (void (TESTDB::*)(int, int)) &TESTDB::aaaa);
 note: candidates are: static void TESTDB::aaaa(int)
 static void aaaa(int a) {printf("xxxxx");};
 note:                 static void TESTDB::aaaa(int, int)
 static void aaaa(int a, int b) {printf("aaaaa");};

有什么想法吗？

谢谢

Answer 1

问题是你的演员(void (TESTDB::*)(int, int))。该转换将指向静态成员函数的指针转换为指向非-静态成员函数的指针，这是不正确的。

由于函数是静态的，您应该简单地将它们转换为指向普通非成员函数的指针：

py::class_<TESTDB>(m, "db")
    .def_static("aaaa", static_cast<void (*)(int, int)>(&TESTDB::aaaa));

Answer 2

仅供参考 - 首先，C++ 标准草案 n3337（本质上是 C++11）的 8.3.1 指针 [dcl.ptr] / 1州

In a declaration T D where D has the form
* attribute-specifier-seq cv-qualifier-seq D1
and the type of the identifier in the declaration T D1 is “derived-declarator-type-list T,” then the type of the identifier of D is “derived-declarator-type-list cv-qualifier-seq pointer to T.” ...

和8.3.3指向成员的指针[dcl.mptr] / 1状态

In a declaration T D where D has the form
nested-name-specifier * attribute-specifier-seq cv-qualifier-seq D1
and the nested-name-specifier denotes a class, and the type of the identifier in the declaration T D1 is “derived-declarator-type-list T”, then the type of the identifier of D is “derived-declarator-type-list cv-qualifier-seq pointer to member of class nested-name-specifier of type T”. ...

这些语句意味着当且仅当函数 TESTDB::aaaa 是一个成员函数 .

接下来，5.2.2 函数调用[expr.call]状态

There are two kinds of function call: ordinary function call and member function⁶³ (9.3) call. ...

其中脚注63是

63) A static member function (9.4) is an ordinary function.

这意味着你的静态成员函数TESTDB::aaaa是一个普通函数，而不是成员函数。因此，您不得在当前演员表中指定 TESTDB::。

总而言之，您必须像这样消除 TESTDB::aaaa 的两个重载的歧义：

Live DEMO

static_cast<void (*)(int, int)>(&TESTDB::aaaa)

无法在 pybind11 中绑定重载的静态成员函数

Unable to bind overloaded static member functions in pybind11

python

c++

function-pointers

member-function-pointers

pybind11