gh-102595: Document `PyObject_Format` c-api function (GH-102596)

(cherry picked from commit 910a64e3013bce821bfac75377cbe88bedf265de)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
Def: https://github.com/python/cpython/blame/5ffdaf748d98da6065158534720f1996a45a0072/Include/abstract.hGH-L389

diff --git a/Doc/c-api/object.rst b/Doc/c-api/object.rst
index feadf503205e09c7cbce555545978037fb9b9f63..29920d24742ff2c1c7c077998ac2669423fc3425 100644 (file)
--- a/Doc/c-api/object.rst
+++ b/Doc/c-api/object.rst
@@ -161,6 +161,15 @@ Object Protocol
    If *o1* and *o2* are the same object, :c:func:`PyObject_RichCompareBool`
    will always return ``1`` for :const:`Py_EQ` and ``0`` for :const:`Py_NE`.
 
+.. c:function:: PyObject* PyObject_Format(PyObject *obj, PyObject *format_spec)
+
+   Format *obj* using *format_spec*. This is equivalent to the Python
+   expression ``format(obj, format_spec)``.
+
+   *format_spec* may be ``NULL``. In this case the call is equivalent
+   to ``format(obj)``.
+   Returns the formatted string on success, ``NULL`` on failure.
+
 .. c:function:: PyObject* PyObject_Repr(PyObject *o)
 
    .. index:: builtin: repr