Extending and Embedding the Python Interpreter
**********************************************

This document describes how to write modules in C or C++ to extend the
Python interpreter with new modules.  Those modules can do what Python
code does – define functions, object types and methods – but also
interact with native libraries or achieve better performance by
avoiding the overhead of an interpreter.  The document also describes
how to embed the Python interpreter in another application, for use as
an extension language.  Finally, it shows how to compile and link
extension modules so that they can be loaded dynamically (at run time)
into the interpreter, if the underlying operating system supports this
feature.

This document assumes basic knowledge about C and Python.  For an
informal introduction to Python, see The Python Tutorial.  The Python
Language Reference gives a more formal definition of the language.
The Python Standard Library documents the existing object types,
functions and modules (both built-in and written in Python) that give
the language its wide application range.

For a detailed description of the whole Python/C API, see the separate
Python/C API reference manual.

To support extensions, Python’s C API (Application Programmers
Interface) defines a set of functions, macros and variables that
provide access to most aspects of the Python run-time system.  The
Python API is incorporated in a C source file by including the header
""Python.h"".

Note:

  The C extension interface is specific to CPython, and extension
  modules do not work on other Python implementations.  In many cases,
  it is possible to avoid writing C extensions and preserve
  portability to other implementations. For example, if your use case
  is calling C library functions or system calls, you should consider
  using the "ctypes" module or the cffi library rather than writing
  custom C code. These modules let you write Python code to interface
  with C code and are more portable between implementations of Python
  than writing and compiling a C extension module.


Recommended third party tools
=============================

This document only covers the basic tools for creating extensions
provided as part of this version of CPython. Some third party tools
offer both simpler and more sophisticated approaches to creating C and
C++ extensions for Python.

While this document is aimed at extension authors, it should also be
helpful to the authors of such tools. For example, the tutorial module
can serve as a simple test case for a build tool or sample expected
output of a code generator.


C API Tutorial
==============

This tutorial describes how to write a simple module in C or C++,
using the Python C API – that is, using the basic tools provided as
part of this version of CPython.

1. Your first C API extension module


Guides for intermediate topics
==============================

This section of the guide covers creating C and C++ extensions without
assistance from third party tools. It is intended primarily for
creators of those tools, rather than being a recommended way to create
your own C extensions.

* Using the C API: Assorted topics

* Defining Extension Types: Tutorial

* Defining Extension Types: Assorted Topics

* Building C and C++ Extensions

* Building C and C++ Extensions on Windows


Embedding the CPython runtime in a larger application
=====================================================

Sometimes, rather than creating an extension that runs inside the
Python interpreter as the main application, it is desirable to instead
embed the CPython runtime inside a larger application. This section
covers some of the details involved in doing that successfully.

* Embedding Python in Another Application
