In the prior chapter, we explored half of the Python/C integration picture: calling C services from Python. This mode lets programmers speed up operations by moving them to C, and to utilize external libraries by wrapping them in C extension modules and types. But the inverse can be just as useful: calling Python from C. By delegating selected components of an application to embedded Python code, we can open them up to onsite changes without having to ship a system’s code.

This chapter tells this other half of the Python/C integration tale. It introduces the Python C interfaces that make it possible for programs written in C-compatible languages to run Python program code. In this mode, Python acts as an embedded control language (what some call a “macro” language). Although embedding is mostly presented in isolation here, keep in mind that Python’s integration support is best viewed as a whole. A system’s structure usually determines an appropriate integration approach: C extensions, embedded code calls, or both. To wrap up, this chapter concludes by discussing a handful of larger integration platforms, such as Component Object Model (COM) and Jython, which present broader component integration possibilities.