Boost Python官方样例（三）

导出C++类（纯虚函数和虚函数）

大致做法就是为class写一个warp，通过get_override方法检测虚函数是否被重载了，如果被重载了调用重载函数，否则调用自身实现，最后导出的时候直接导出warp类，但是类名使用class，析构函数不需要导出，因为它会被自动调用

纯虚函数

编写C++函数实现

1$ vim virt.h
2#include <iostream>
3#include <boost/python/wrapper.hpp>
4
5// 用class会出现编译问题， 不知道是不是和boost::python里面的class产生了冲突
6struct Base
7{
8    virtual ~Base() { std::cout << "Base destructor" << std::endl; };
9    virtual int f() = 0;
10};
11
12struct BaseWrap : Base, boost::python::wrapper<Base>
13{
14    int f()
15    {
16        return this->get_override("f")();
17    }
18};

编写Boost.Python文件

1$ vim virt_wrapper.cpp
2#include <boost/python/module.hpp>
3#include <boost/python/class.hpp>
4#include <boost/python/pure_virtual.hpp>
5#include "virt.h"
6
7using namespace boost::python;
8using namespace boost::python::detail;
9
10BOOST_PYTHON_MODULE_INIT(virt_ext)
11{
12    class_<BaseWrap, boost::noncopyable>("Base")
13            .def("f", pure_virtual(&Base::f));
14}

运行python测试库文件

1$ python
2>>> import virt_ext
3>>> def f():
4...     o = virt_ext.Base()
5...
6>>> f()
7Base destructor

虚函数

编写C++函数实现

1$ vim virt.h
2#include <boost/python/wrapper.hpp>
3#include <boost/python/call.hpp>
4
5struct Base
6{
7    virtual ~Base() { std::cout << "Base destructor" << std::endl; };
8    virtual int f() = 0;
9};
10
11struct BaseWrap : Base, boost::python::wrapper<Base>
12{
13    int f()
14    {
15        return this->get_override("f")();
16    }
17};
18
19struct Derived: Base
20{
21    virtual ~Derived() { std::cout << "Derived destructor" << std::endl; }
22    virtual int f() { std::cout << "Override by Derived" << std::endl; return 0; }
23};
24
25struct DerivedWrap : Derived, boost::python::wrapper<Derived>
26{
27    int f()
28    {
29        if (boost::python::override func = this->get_override("f"))
30            return func();
31        return Derived::f();
32    }
33};

编写Boost.Python文件

1$ vim virt_wrapper.cpp
2#include <boost/python/module.hpp>
3#include <boost/python/class.hpp>
4#include <boost/python/pure_virtual.hpp>
5#include "virt.h"
6
7using namespace boost::python;
8using namespace boost::python::detail;
9
10BOOST_PYTHON_MODULE_INIT(virt_ext)
11{
12// 可以导出Base也可以不导出Base
13//    class_<BaseWrap, boost::noncopyable>("Base")
14//            .def("f", pure_virtual(&Base::f));
15    class_<DerivedWrap, boost::noncopyable>("Derived")
16            .def("f", &Derived::f);
17}

运行python测试库文件

1>>> import virt_ext
2>>> b = virt_ext.Base()
3>>> d = virt_ext.Derived()
4>>> d.f()
5Override by Derived
60
7>>> b.f()
8Traceback (most recent call last):
9  File "<stdin>", line 1, in <module>
10RuntimeError: Pure virtual function called
11>>> exit()
12Base destructor
13Derived destructor
14Base destructor