This doesn't compile Python to machine code. But allows to create a shared library to call Python code.
If what you are looking for is an easy way to run Python code from C without relying on execp stuff. You could generate a shared library from python code wrapped with a few calls to Python embedding API. Well the application is a shared library, an .so that you can use in many other libraries/applications.
Here is a simple example which create a shared library, that you can link with a C program. The shared library executes Python code.
The python file that will be executed is pythoncalledfromc.py
:
# -*- encoding:utf-8 -*-
# this file must be named "pythoncalledfrom.py"
def main(string): # args must a string
print "python is called from c"
print "string sent by «c» code is:"
print string
print "end of «c» code input"
return 0xc0c4 # return something
You can try it with python2 -c "import pythoncalledfromc; pythoncalledfromc.main('HELLO')
. It will output:
python is called from c
string sent by «c» code is:
HELLO
end of «c» code input
The shared library will be defined by the following by callpython.h
:
#ifndef CALL_PYTHON
#define CALL_PYTHON
void callpython_init(void);
int callpython(char ** arguments);
void callpython_finalize(void);
#endif
The associated callpython.c
is:
// gcc `python2.7-config --ldflags` `python2.7-config --cflags` callpython.c -lpython2.7 -shared -fPIC -o callpython.so
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <python2.7/Python.h>
#include "callpython.h"
#define PYTHON_EXEC_STRING_LENGTH 52
#define PYTHON_EXEC_STRING "import pythoncalledfromc; pythoncalledfromc.main(\"%s\")"
void callpython_init(void) {
Py_Initialize();
}
int callpython(char ** arguments) {
int arguments_string_size = (int) strlen(*arguments);
char * python_script_to_execute = malloc(arguments_string_size + PYTHON_EXEC_STRING_LENGTH);
PyObject *__main__, *locals;
PyObject * result = NULL;
if (python_script_to_execute == NULL)
return -1;
__main__ = PyImport_AddModule("__main__");
if (__main__ == NULL)
return -1;
locals = PyModule_GetDict(__main__);
sprintf(python_script_to_execute, PYTHON_EXEC_STRING, *arguments);
result = PyRun_String(python_script_to_execute, Py_file_input, locals, locals);
if(result == NULL)
return -1;
return 0;
}
void callpython_finalize(void) {
Py_Finalize();
}
You can compile it with the following command:
gcc `python2.7-config --ldflags` `python2.7-config --cflags` callpython.c -lpython2.7 -shared -fPIC -o callpython.so
Create a file named callpythonfromc.c
that contains the following:
#include "callpython.h"
int main(void) {
char * example = "HELLO";
callpython_init();
callpython(&example);
callpython_finalize();
return 0;
}
Compile it and run:
gcc callpythonfromc.c callpython.so -o callpythonfromc
PYTHONPATH=`pwd` LD_LIBRARY_PATH=`pwd` ./callpythonfromc
This is a very basic example. It can work, but depending on the library it might be still difficult to serialize C data structures to Python and from Python to C. Things can be automated somewhat...
Nuitka might be helpful.
Also there is numba but they both don't aim to do what you want exactly. Generating a C header from Python code is possible, but only if you specify the how to convert the Python types to C types or can infer that information. See python astroid for a Python ast analyzer.