Python的C/C++扩展之boost_python扩展

前面讲述了Python使用ctypes直接调用动态库和使用Python的C语言API封装C函数,本文概述方便封装C++类给Python使用的boost_python库。

安装boost python库:

sudo aptitude install libboost-python-dev

示例

下面代码简单实现了一个普通函数maxab()和一个Student类:

#include <iostream>
#include <string>

int maxab(int a, int b) { return a>b?a:b; }

class Student {
private:
int age;
std::string name;

public:
Student() {}
Student(std::string const& _name, int _age) { name=_name; age=_age; }

static void myrole() { std::cout << “I’m a student!” << std::endl; }

void whoami() { std::cout << “I am “ << name << std::endl; }

bool operator==(Student const& s) const { return age == s.age; }
bool operator!=(Student const& s) const { return age != s.age; }

};

使用boost.python库封装也很简单,如下代码所示:

#include <Python.h>
#include <boost/python.hpp>
#include <boost/python/suite/indexing/vector_indexing_suite.hpp>
#include <vector>

#include “student.h”

using namespace boost::python;

BOOST_PYTHON_MODULE(student) {
// This will enable user-defined docstrings and python signatures,
// while disabling the C++ signatures
scope().attr(“__version__”) = “1.0.0”;
scope().attr(“__doc__”) = “a demo module to use boost_python.”;
docstring_options local_docstring_options(true, false, false);
def(
“maxab”, &maxab, “return max of two numbers.n”
);

class_<Student>(“Student”, “a class of student”)
.def(init<>())
.def(init<std::string, int>())
// methods for Chinese word segmentation
.def(
“whoami”, &Student::whoami, “method’s doc string…”
)
.def(
“myrole”, &Student::myrole, “method’s doc string…”
)
.staticmethod(“myrole”);
// 封装STL
class_<std::vector<Student> >(“StudentVec”)
.def(vector_indexing_suite<std::vector<Student> >())
;
}

上述代码还是include了Python.h文件,如果不include的话,会报错误:

wrap_python.hpp:50:23: fatal error: pyconfig.h: No such file or directory

编译

编译以上代码有两种方式,一种是在命令行下面直接使用g++编译:

g++ -I/usr/include/python2.7  -fPIC wrap_student.cpp -lboost_python -shared -o student.so

首先指定Python.h的路径,如果是Python 3的话就要修改为相应的路径,编译wrap_student.cpp要指定-fPIC参数,链接(-lboost_python)生成动态库(-shared)。 生成的student.so动态库就可以被python直接import使用了

In [1]: import student

In [2]: student.maxab(2, 5)
Out[2]: 5

In [3]: s = student.Student(‘Tom’, 12)

In [4]: s.whoami()
I am Tom

In [5]: s.myrole()
I‘m a student!

另外一直方法是用python的setuptools编写setup.py脚本:

#!/usr/bin/env python

from setuptools import setup, Extension

setup(name=“student”,
ext_modules=[
Extension(“student”, [“wrap_student.cpp”],
libraries = [“boost_python”])
])

然后执行命令编译:

python setup.py build
or
sudo python setup.py install

未经允许不得转载:996ICU » Python的C/C++扩展之boost_python扩展

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