Why should PyImport_AppendInittab() be called before Py_Initialize()?

Question

According to the documentation, PyImport_AppendInittab "should be called before Py_Initialize()."

There is no explanation of why this is the case, and ignoring this advice yields a working application. So, since this is working, under what circumstances will it not work?

Answer 1

Because the documentation says so; and violating the API might yield a working application today but not tomorrow.

A couple of issues you might encounter:

• sys.builtin_module_names is initialized within Py_Initialize, so it won't contain your module
• PyImport_AppendInittab does not take any locks, so if you call it after Py_Initialize in a multithreaded application you could get memory corruption