Home > Backend Development > C++ > body text

How can I expose a C interface to Python for implementation?

Barbara Streisand
Release: 2024-11-06 02:19:02
Original
401 people have browsed it

How can I expose a C   interface to Python for implementation?

Exposing a C Interface to Python for Implementation

Objective

Integrate Python implementations of a C interface into an existing C program, allowing Python implementations to be used seamlessly within the larger program.

Interface Definition

Consider the following C interface definition:

<code class="cpp">class myif {
public:
  virtual float myfunc(float a) = 0;
};</code>
Copy after login

Importing and Extending the Interface in Python

  1. Enable Polymorphism with SWIG:

    %module(directors="1") module
    
    %include "myif.h"
    Copy after login
  2. Create a Python Implementation:

    <code class="python">import module
    
    class MyCl(module.myif):
      def __init__(self):
        module.myif.__init__(self)
      def myfunc(self, a):
        return a * 2.0</code>
    Copy after login

Embedding Python in C

  1. Initialize Python (main.cc):

    <code class="cpp">Py_Initialize();</code>
    Copy after login
  2. Import the Python Module:

    <code class="cpp">PyObject *module = PyImport_Import(PyString_FromString("mycl"));</code>
    Copy after login
  3. Create Instance and Execute Function:

    <code class="cpp">PyObject *instance = PyRun_String("mycl.MyCl()", Py_eval_input, dict, dict);
    double ret = PyFloat_AsDouble(PyObject_CallMethod(instance, "myfunc", (char *)"(O)" ,PyFloat_FromDouble(input)));</code>
    Copy after login
  4. Finalization:

    <code class="cpp">Py_Finalize();</code>
    Copy after login

Converting Python Object to C Pointer

  1. Exposing SWIG Runtime:

    swig -Wall -c++ -python -external-runtime runtime.h
    Copy after login
  2. Recompile SWIG Module:

    g++ -DSWIG_TYPE_TABLE=myif -Wall -Wextra -shared -o _module.so myif_wrap.cxx -I/usr/include/python2.7 -lpython2.7
    Copy after login
  3. Helper Function for Conversion:

    <code class="cpp">myif *python2interface(PyObject *obj) {
      ...
    }</code>
    Copy after login

Final Implementation in main.cc

<code class="cpp">int main() {
  ...
  myif *inst = python2interface(instance);
  std::cout << inst->myfunc(input) << std::endl;
  ...
}</code>
Copy after login

By following these steps, one can successfully implement Python implementations of a C interface and seamlessly integrate them into larger C programs, providing greater flexibility and extensibility.

The above is the detailed content of How can I expose a C interface to Python for implementation?. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template