I’m glad there is more clarity here. And thanks to Erlend Egeberg Aasland for championing the PR!
—Guido On Thu, Mar 25, 2021 at 09:30 Victor Stinner <vstin...@python.org> wrote: > Hi, > > A new Include/README.rst file was just added to document the 3 C API > provided by CPython: > > * Include/: Limited C API > * Include/cpython/: CPython implementation details > * Include/internal/: The internal API > > I would like to note that *new* public C API functions must no longer > steal references or return borrowed references. > > Don't worry, there is no plan to deprecate or remove existing > functions which do that, like PyModule_AddObject() (streal a > reference) or PyDict_GetItem() (return a borrowed reference). The > policy is only to *add* new functions. > > IMO for the *internal* C API, it's fine to continue doing that for > best performances. > > Moreover, the limited C API must not expose "implementation details". > For example, structure members must not be accessed directly, because > most structures are excluded from the limited C API. A function call > hiding implementation details is usually better. > > Here is a copy of the current Include/README.rst file: > > The Python C API > ================ > > The C API is divided into three sections: > > 1. ``Include/`` > 2. ``Include/cpython/`` > 3. ``Include/internal/`` > > > Include: Limited API > ==================== > > ``Include/``, excluding the ``cpython`` and ``internal`` subdirectories, > contains the public Limited API (Application Programming Interface). > The Limited API is a subset of the C API, designed to guarantee ABI > stability across Python 3 versions, and is defined in :pep:`384`. > > Guidelines for expanding the Limited API: > > - Functions *must not* steal references > - Functions *must not* return borrowed references > - Functions returning references *must* return a strong reference > - Macros should not expose implementation details > - Please start a public discussion before expanding the API > - Functions or macros with a ``_Py`` prefix do not belong in ``Include/``. > > It is possible to add a function or macro to the Limited API from a > given Python version. For example, to add a function to the Limited API > from Python 3.10 and onwards, wrap it with > ``#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030A0000``. > > > Include/cpython: CPython implementation details > =============================================== > > ``Include/cpython/`` contains the public API that is excluded from the > Limited API and the Stable ABI. > > Guidelines for expanding the public API: > > - Functions *must not* steal references > - Functions *must not* return borrowed references > - Functions returning references *must* return a strong reference > > > Include/internal: The internal API > ================================== > > > With PyAPI_FUNC or PyAPI_DATA > ----------------------------- > > Functions or structures in ``Include/internal/`` defined with > ``PyAPI_FUNC`` or ``PyAPI_DATA`` are internal functions which are > exposed only for specific use cases like debuggers and profilers. > > > With the extern keyword > ----------------------- > > Functions in ``Include/internal/`` defined with the ``extern`` keyword > *must not and can not* be used outside the CPython code base. Only > built-in stdlib extensions (built with the ``Py_BUILD_CORE_BUILTIN`` > macro defined) can use such functions. > > When in doubt, new internal C functions should be defined in > ``Include/internal`` using the ``extern`` keyword. > > Victor > -- > Night gathers, and now my watch begins. It shall not end until my death. > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/QKFDGIAFPZJZE22GJ5OOMXOWQGFEDSU5/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- --Guido (mobile)
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