Python and C extension implementation methods

One, Python and C extensions

CPython is written in C, and Python extensions can be written in C and easily ported to C + +.

The python extension that you write needs to be compiled into a shared library of. So.

The Python program.

Official Document: Https://docs.python.org/2/extending/extending.html#writing-extensions-in-c

Ii. examples

Spamspam.  System("ls-l")     

We need to create a SPAM.C file module, which is the C implementation. Must begin with

#include <Python.h>

The following implementations are implemented:

StaticPyobject *Spam_system (Pyobject*self, Pyobject *args) {    Const Char*comment; intSTS; if(! Pyarg_parsetuple (args,"s", &command)) returnNULL; STS=System (command); returnPy_buildvalue ("I", STS);}

The C function has two parameters in the Python extension of the above function: self, args, these two are required.

Third, module method and function initialization

1, define the module and help document. The module is called system, which specifies the execution function Spam_system, which helps the document "execute a shell command"

Static Pymethoddef spammethods[] = {     {"system""Execute a shell command . " },    0, NULL}};

After compiling, import the module, execute the following help command, the document will appear

In [5]: Help (spam) to help on module    spam:name    spamfile/usr/lib/python2.  6/site-packages/spam.sofunctions    System (...)        Execute a shell command.

2, initial spam, initialization module function must be init[module], consistent

void Initspam () {    py_initmodule ("spam", Spammethods);}

Third, compile

1, compile the module, you need to write setup.py file

# !/usr/bin/env python # -*-coding:utf-8-*-  from Import  "spam"Setup (name=mod, Ext_modules=[extension (MOD, sources=['  spam.c']))

Module name name and Extension module.

2, to compile

[[email protected] pycext]#python setup.py buildrunning buildrunning build_extbuilding'spam'EXTENSIONGCC-pthread-fno-strict-aliasing-o2-g-pipe-wall-wp,-d_fortify_source=2-fexceptions-fstack-protector--param= Ssp-buffer-size=4-m32-march=i686-mtune=atom-fasynchronous-unwind-tables-d_gnu_source-fpic-fwrapv-dndebug-o2-g- Pipe-wall-wp,-d_fortify_source=2-fexceptions-fstack-protector--param=ssp-buffer-size=4-m32-march=i686-mtune= Atom-fasynchronous-unwind-tables-d_gnu_source-fpic-fwrapv-fpic-i/usr/include/python2.6-c Spam.c-o build/ temp.linux-i686-2.6/spam.oin file included from/usr/include/python2.6/pyconfig.h:4,                  from/usr/include/python2.6/python.h:8,                  fromSpam.c:3:/usr/include/python2.6/pyconfig-32.h:1034:1: Warning:"_posix_c_source"Redefinedin file included from/usr/include/stdio.h:28,                  fromSpam.c:1:/usr/include/features.h:162:1: Warning:this isThe location of the previous Definitionin file included from/usr/include/python2.6/pyconfig.h:4,                  from/usr/include/python2.6/python.h:8,                  fromSpam.c:3:/usr/include/python2.6/pyconfig-32.h:1043:1: Warning:"_xopen_source"Redefinedin file included from/usr/include/stdio.h:28,                  fromSpam.c:1:/usr/include/features.h:164:1: Warning:this isThe location of the previous DEFINITIONGCC-pthread-shared Build/temp.linux-i686-2.6/spam.o-l/usr/lib-lpython2.6-o build/lib.linux-i686-2.6/spam.so

Generate a Build folder with Spam.so Library

[[email protected] pycext] # lsbuild  setup.py  spam.c

3. Installation

[[email protected] pycext] # python setup.py Install running installrunning buildrunning build_extrunning install_libcopying build/lib.linux-i686-2.6/spam.so- >/usr/lib/python2.6/site-/usr/lib/python2.6/site-packages/spam-0.0.0-py2.6.egg-/usr/lib/ Python2.6/site-packages/spam-0.0.0-py2.6.egg-info

Execute the command as above, and install it.

Iv. Use of modules

Import Spamin [2]: Spam.system ("ls-la")drwxr-xr-x.  3 root root 4096 Apr  8 22:07 drwxr-xr-x. Root root 4096 Apr  8 21:01. DRWXR-xr-x.  4 root root 4096 Apr  8 21:51 build-rw-r--r--.  1 root root  171 APR  8 21:48 setup.py-rw-r--r--.  1 root root  549 Apr  8 22:07 spam.cout[2]: 0In [

As above, for Python extension related content ...

Spam.c

#include <stdio.h>#include<stdlib.h>#include"Python.h"StaticPyobject *Spam_system (Pyobject*self, Pyobject *args) {    Const Char*command; intSTS; if(! Pyarg_parsetuple (args,"s", &command)) returnNULL; STS=System (command); returnPy_buildvalue ("I", STS);}StaticPymethoddef spammethods[] = {    {"system", Spam_system, Meth_varargs,"Execute a shell command."}, {null, NULL,0, NULL}};voidInitspam () {Py_initmodule ("spam", spammethods);}intMainintargcChar*argv[]) {    return 0;}

setup.py

# !/usr/bin/env python # -*-coding:utf-8-*-  from Import  "spam"Setup (name=mod, Ext_modules=[extension (MOD, sources=[ ' SPAM.C ']))

Python and C extension implementation methods