Swig & Python calls C code

    SWIG, Simplified Wrapper and Interface Generator, It's a software development tool , It will C and C++ The program is connected with various high-level programming languages .SWIG Available for different types of target languages , Including common scripting languages , Such as Javascript、Perl、PHP、Python、Tcl and Ruby. The list of supported languages also includes non scripting languages , Such as C#,D,Go language,Java, Include Android,Lua,OCaml,Octave,Scilab and R. It also supports several kinds of interpretation and compilation Scheme Realization （Guile,MzScheme/Racket）

 

agt-get install swig

usage

1. establish C Files and header files

example.c

#include "example.h"
int fact(int n) {
if (n < 0) {
return 0;
}
if (n == 0) {
return 1;
}
else {
return n * fact(n-1);
}
}

example.h

int fact(int n);

2. To write swig Interface file   example.i

%module example
%{
#define SWIG_FILE_WITH_INIT
#include "example.h"
%}
int fact(int n)

• %module The following name is the name of the encapsulated module ,Python Load the program by this name .
• %{…%} Added between , It generally contains some function declarations and header files required by this file .
• Last part , Declare the functions and variables to be encapsulated .

swig The simplicity of the interface file is that it is easy to write

3.   Call... Using the command line Swig Methods produce Python modular

swig -python example.i

 

It will be generated after execution 2 New file ：example_wrap.c,example.py

 

4. use setup.py Generate so file

setup.py

from distutils.core import setup, Extension
example_module = Extension('_example',
sources=['example_wrap.c', 'example.cpp'],
)
setup(name='example',
version='0.1',
author="SWIG Docs",
description="""Simple swig example from docs""",
ext_modules=[example_module],
py_modules=["example"],
)

Derived .so File naming needs to start with an underscore _

Compile the generated so file

python setup.py build_ext --inplace

5.  stay C Call in language program

test.py

import _example
print(_example.fact(4))