Boost Python学习笔记(二)
你将学到什么
- 如何在Python中调用C++代码
- 如何在C++中调用Python代码
在Python中调用C++代码
首先定义一个动物类(include/animal.h)
#pragma once
#include <string>
class Animal
{
public:
Animal(std::string name);
virtual ~Animal();
virtual void call();
virtual void move();
void eat(std::string food);
protected:
std::string name_;
};
其实现代码如下(src/animal.cpp)
#include <iostream>
#include "animal.h"
Animal::Animal(std::string name):name_(name)
{
}
Animal::~Animal()
{
}
void Animal::call()
{
std::cout << name_ << ": call" << std::endl;
}
void Animal::move()
{
std::cout << name_ << ": moving" << std::endl;
}
void Animal::eat(std::string food)
{
std::cout << name_ << ": eat " << food << std::endl;
}
接着编写其导出代码(include/boost_wrapper.h)
#pragma once
#include <boost/python/wrapper.hpp>
#include "animal.h"
class AnimalWrap: public Animal, public boost::python::wrapper<Animal>
{
public:
AnimalWrap(std::string name);
virtual ~AnimalWrap();
void call();
void move();
};
其导出实现如下(src/boost_wrapper.cpp)
#include <boost/python/module.hpp>
#include <boost/python/class.hpp>
#include "boost_wrapper.h"
using namespace boost::python;
using namespace boost::python::detail;
AnimalWrap::AnimalWrap(std::string name):Animal(name)
{
}
AnimalWrap::~AnimalWrap()
{
}
void AnimalWrap::call()
{
if (override func = this->get_override("call"))
func();
Animal::call();
}
void AnimalWrap::move()
{
if (override func = this->get_override("move"))
func();
Animal::move();
}
BOOST_PYTHON_MODULE_INIT(boost)
{
class_<AnimalWrap, boost::noncopyable>("Animal", init<std::string>())
.def("call", &Animal::call)
.def("move", &Animal::move)
.def("eat", &Animal::eat);
}
最后编写CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
project(boost)
set(CMAKE_CXX_FLAGS "-Wall -g")
### 此处的动态库名必须和BOOST_PYTHON_MODULE()中定义的保持一致,即最后生成的库必须名为boost.so
file(GLOB SRC "src/*.cpp")
add_library(boost SHARED ${SRC})
set_target_properties(boost PROPERTIES PREFIX "")
#dependencies
INCLUDE(FindPkgConfig)
pkg_check_modules(PYTHON REQUIRED python)
include_directories(include /usr/local/include ${PYTHON_INCLUDE_DIRS})
link_directories(/usr/local/lib ${PYTHON_LIBRARY_DIRS})
target_link_libraries(boost boost_python)
项目最终目录结构
# tree .
.
├── build
├── CMakeLists.txt
├── include
│ ├── animal.h
│ └── boost_wrapper.h
└── src
├── animal.cpp
└── boost_wrapper.cpp
3 directories, 5 files
编译
# cd build
# cmake ..
# make
编写测试文件(build/zoo.py)
import boost
def show():
wolf = boost.Animal("wolf")
wolf.eat("beef")
goat = boost.Animal("gota")
goat.eat("grass")
if __name__ == '__main__':
show()
执行测试
# cd build
# python zoo.py
wolf: eat beef
gota: eat grass
在C++中调用Python代码
在上个项目的根目录添加源文件(main.cpp)
#include <iostream>
#include <boost/python.hpp>
using namespace boost::python;
int main()
{
Py_Initialize();
if (!Py_IsInitialized())
{
std::cout << "Initialize failed" << std::endl;
return -1;
}
try
{
object sys_module = import("sys");
str module_directory(".");
sys_module.attr("path").attr("insert")(1, module_directory);
object module = import("zoo");
module.attr("show")();
}
catch (const error_already_set&)
{
PyErr_Print();
}
Py_Finalize();
return 0;
}
修改CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
project(boost)
set(CMAKE_CXX_FLAGS "-Wall -g")
### 此处的动态库名必须和BOOST_PYTHON_MODULE()中定义的保持一致,即最后生成的库必须名为boost.so
file(GLOB SRC "src/*.cpp")
add_library(boost SHARED ${SRC})
set_target_properties(boost PROPERTIES PREFIX "")
add_executable(core main.cpp)
#dependencies
INCLUDE(FindPkgConfig)
pkg_check_modules(PYTHON REQUIRED python)
include_directories(include /usr/local/include ${PYTHON_INCLUDE_DIRS})
link_directories(/usr/local/lib ${PYTHON_LIBRARY_DIRS})
target_link_libraries(boost boost_python)
target_link_libraries(core boost ${PYTHON_LIBRARIES})
编译并执行测试
# cd build
# cmake ..
# make
# ./core
wolf: eat beef
gota: eat grass
总结
考虑这样一个需求,我们要展示一个动物园中的动物,但是动物的种类和个数都不固定,这就导致我们动物园的show
方法需要经常变动,有什么办法可以避免程序的反复编译呢?一种方式就是使用配置文件,将需要展示的动物写入配置文件,然后动物园的show
方法通过解析配置文件来生成需要展示的内容;另一种方式就是通过Python脚本来实现,因为Python脚本不需要编译,相比于配置文件的方式,Python脚本的方式不需要设计配置文件格式,也不需要实现复杂的解析逻辑,使用起来更加灵活。
在上面的例子中,我们使用Python脚本实现了原本应该在main.cpp
中实现的show
方法,然后在main.cpp
中调用它,后面如果有改动我们直接修改Python脚本即可,无需重编程序。