[python] 最簡單的方法, 呼叫 python 模組 using cython

How to invoke python code from C using cython

井民全, Jing, mqjing@gmail.com

這文章 go through 了一次, 如何從 C 來呼叫 python module 的 code.

內容包含:

• 最簡單的 python code
• 撰寫最簡單的 cython module 來呼叫 python function
• 如何把 cython 模組 轉成 object, 讓 C 呼叫
• 最簡單的方法呼叫 cython module 使用 C

Enjoy

Jing.

Pytyon Code

my_python.py

def my_python_module(): print('1234')

Quick

# transfer and build the object cython my_python.py gcc my_python.c -o my_python.o -shared -pthread -fPIC -fwrapv -O2 -Wall -fno-strict-aliasing -I/usr/include/python3.5 # create bridge bridge.pyx from my_python import * cdef public void call_python_module(): my_python_module() cython bridge.pyx gcc bridge.c -o bridge.o -shared -pthread -fPIC -fwrapv -O2 -Wall -fno-strict-aliasing -I/usr/include/python3.5 # usage main.c #include Python.h // 兩邊加上角括號 #include "bridge.h" int main() { Py_Initialize(); PyInit_bridge(); // init the bridge module call_python_module(); // call bridge Py_Finalize(); return 0; } gcc main.c -ldl bridge.o -I/usr/include/python3.5 -L/usr/lib/python3.5/config-3.5m-x86_64-linux-gnu -lpython3.5 # run ./a.out

別忘記環境變數

(a) Bridge.so Path

LD_LIBRARY_PATH=.:$LD_LIBRARY_PATH

export LD_LIBRARY_PATH

(b) Python Module Path

PYTHONPATH=.:$PYTHONPATH

export PYTHONPATH

Detail

# Transfer the Source

cython my_python.py

gcc my_python.c -o my_python.o  -shared -pthread -fPIC -fwrapv -O2 -Wall -fno-strict-aliasing  -I/usr/include/python3.5

Create the bridge

bridge.pyx

from my_python import * cdef public void call_python_module():    my_python_module()

cython bridge.pyx

gcc bridge.c -o bridge.o  -shared -pthread -fPIC -fwrapv -O2 -Wall -fno-strict-aliasing  -I/usr/include/python3.5

Usage

Write main.c

#include #include "bridge.h" int main() { Py_Initialize(); PyInit_bridge(); // init the bridge module call_python_module(); // call bridge Py_Finalize(); return 0; }

Build the app

gcc main.c -ldl bridge.o -I/usr/include/python3.5 -L/usr/lib/python3.5/config-3.5m-x86_64-linux-gnu -lpython3.5

Setup Path Environment

(a) setup bridge.so path

Command

LD_LIBRARY_PATH=. export LD_LIBRARY_PATH

(b) Python Module Path

PYTHONPATH=.:$PYTHONPATH

Run your application

./a.out