我尝试通过C语言编写一个Python的模块,但是我的C程序本身又依赖于一个第三方的库(libwiringPi.so),当我在Python源程序中import我生成的库时,会提示函数未定义,这些函数都是那个第三方库里的,我应该怎样编译才能让我编译出的模块可以动态链接那个库?
我也尝试过使用gcc手动编译动态链接库,然后用ctyes,但是报一样的错误;生成模块的C代码和setup.py代码都是基于Python源码包中的demo程序。
我的C程序代码
/* Example of embedding Python in another program */
#include "python2.7/Python.h"
#include <wiringPi.h>
void initdht11(void); /* Forward */
int main(int argc, char **argv)
{
/* Initialize the Python interpreter. Required. */
Py_Initialize();
/* Add a static module */
initdht11();
/* Exit, cleaning up the interpreter */
Py_Exit(0);
return 0;
}
/* A static module */
/* 'self' is not used */
static PyObject *
dht11_foo(PyObject *self, PyObject* args)
{
wiringPiSetup();
return PyInt_FromLong(42L);
}
static PyMethodDef dht11_methods[] = {
{"foo", dht11_foo, METH_NOARGS,
"Return the meaning of everything."},
{NULL, NULL} /* sentinel */
};
void
initdht11(void)
{
PyImport_AddModule("dht11");
Py_InitModule("dht11", dht11_methods);
}
setup.py
from distutils.core import setup, Extension
dht11module = Extension('dht11',
library_dirs = ['/usr/lib'],
include_dirs = ['/usr/include'],
sources = ['math.c'])
setup (name = 'dht11',
version = '1.0',
description = 'This is a demo package',
author = 'Martin v. Loewis',
author_email = 'martin@v.loewis.de',
url = 'https://docs.python.org/extending/building',
long_description = '''
This is really just a demo package.
''',
ext_modules = [dht11module])
错误信息
Traceback (most recent call last):
File "test.py", line 1, in <module>
import dht11
ImportError: /usr/local/lib/python2.7/dist-packages/dht11.so: undefined symbol: wiringPiSetup
哎,早上醒来突然想到,赶紧试了一下。
出现这个问题是因为在编译的时候需要加
-lwiringPi
选项来引用这个库,但是我仔细看了以下执行python setup.py build
之后执行的编译命令,根本就没有加这个选项,解决方式很简单,只需要修改一下setup.py,在Extension里面加上libraries = ['wiringPi']
这个参数就行了,修改后的setup.py变成如下样子