c++ - boost-python纯虚拟检测缺失实现

Question

我有一个 C++ 类，它有一个使用 boost-python 暴露给 python 的纯虚方法。我正在从 C++ 调用虚函数并假设虚函数是在 python 中实现的。如果实现了该功能，一切都会起作用，但如果没有实现，我会得到一个讨厌的异常。

我正在尝试找到一种方法来检测该方法是否实际上在我加载类时调用而无需调用

代码大概是这样的

#include <boost/python.hpp>

using namespace boost::python;

public Foo {
public:
   void func() = 0;
}

class PyFoo : public Foo, public boost::python::wrapper<Foo> {
public:
    void func() override {
        get_override("func")();
    }
};

BOOST_PYTHON_MODULE(example)
{
    using namespace boost::python;
    class_<PyFoo>, boost::noncopyable>("Foo")
        .def("func", pure_virtual(&PyFoo::func))
        ;
}

void create {
    object main_module = import("__main__");
    object main_namespace = main_module.attr("__dict__");

    std::string overrideCommand(
    R"(
    import example

    class MyFoo(example.Foo):
        def __init__(self):
            example.Foo.__init__(self)

    # virtual function in C++. (Should be defined)
    #    def func(self):
    #        print('func called')
    )");

    boost::python::exec(overrideCommand.c_str(), main_namespace);
    result = eval("MyFoo()", main_namespace);

    // Can I detect if 'result' has func implemented? If I call it and it
    // is not defined death results. I have tried:
    object attr = result.attr("func");

    // but attr always seems to be set even if there is no function,
    // I think from the base class Foo.

    // This is the call:
    Foo& t = extract<Foo&>(result);
    t.func();
}

Answer 1

您可以使用 PyCallable_Check .

if (!PyCallable_Check(result.func()))
{
    PyErr_SetString(PyExc_TypeError, error_msg.str().c_str());
    python::throw_error_already_set();
}