Objects/abstract.c

Source:

cpython 3.14 @ ab2d84fe1023/Objects/abstract.c ↗

Objects/abstract.c implements the C-level abstract object protocol: the set of PyObject_*, PyNumber_*, PySequence_*, and PyMapping_* functions that operate on any Python object via its type's slot table. This file is the bridge between C extension code and Python's operator semantics.

Map

Lines	Symbol	Role
1-200	PyObject_Call, _PyObject_CallMethod*	Call protocol
201-450	PyObject_GetAttr, PyObject_SetAttr, PyObject_GenericGetAttr	Attribute access
451-700	PyObject_GetItem, PyObject_SetItem, PyObject_DelItem	Subscript protocol
701-1000	PyNumber_Add, PyNumber_Subtract, ..., PyNumber_Index	Numeric protocol
1001-1400	PySequence_Length, PySequence_GetItem, PySequence_Contains, PySequence_List, PySequence_Tuple	Sequence protocol
1401-1700	PyMapping_Size, PyMapping_GetItemString, PyMapping_Keys, PyMapping_Values, PyMapping_Items	Mapping protocol
1701-2000	PyObject_GetIter, PyIter_Next, PyAIter_Send	Iterator protocol
2001-2900	PyObject_IsTrue, PyObject_Not, PyObject_Repr, PyObject_Str, PyObject_ASCII, PyObject_Bytes	Miscellaneous protocol

Reading

PyObject_Call

The primary call entry point. Delegates to tp_call if present, otherwise raises TypeError.

// CPython: Objects/abstract.c:290 PyObject_Call
PyObject *
PyObject_Call(PyObject *callable, PyObject *args, PyObject *kwargs)
{
    ...
    ternaryfunc call = Py_TYPE(callable)->tp_call;
    if (call == NULL) {
        PyErr_Format(PyExc_TypeError,
                     "'%.200s' object is not callable",
                     Py_TYPE(callable)->tp_name);
        return NULL;
    }
    PyObject *result = call(callable, args, kwargs);
    ...
    return result;
}

PyObject_GetAttr

// CPython: Objects/abstract.c:906 PyObject_GetAttr
PyObject *
PyObject_GetAttr(PyObject *v, PyObject *name)
{
    PyTypeObject *tp = Py_TYPE(v);
    if (tp->tp_getattro != NULL)
        return (*tp->tp_getattro)(v, name);
    ...
}

Dispatches through tp_getattro. The default tp_getattro is PyObject_GenericGetAttr, which searches the MRO for data descriptors, the instance __dict__, then non-data descriptors.

PyNumber_Add and binary operator dispatch

// CPython: Objects/abstract.c:1012 binary_op1
static PyObject *
binary_op1(PyObject *v, PyObject *w, const int op_slot, const char *op_name)
{
    binaryfunc slotv = NB_BINOP(Py_TYPE(v)->tp_as_number, op_slot);
    binaryfunc slotw = NB_BINOP(Py_TYPE(w)->tp_as_number, op_slot);
    ...
    if (slotv) {
        x = slotv(v, w);
        if (x != Py_NotImplemented) return x;
        Py_DECREF(x);
    }
    if (slotw && slotw != slotv) {
        x = slotw(w, v);
        ...
    }
    Py_RETURN_NOTIMPLEMENTED;
}

Tries the left operand's slot first; falls back to the right operand's reflected slot if Py_NotImplemented is returned.

PyIter_Next

// CPython: Objects/abstract.c:3031 PyIter_Next
PyObject *
PyIter_Next(PyObject *iter)
{
    PyObject *result;
    result = (*Py_TYPE(iter)->tp_iternext)(iter);
    if (result == NULL && !PyErr_Occurred())
        PyErr_SetNone(PyExc_StopIteration);
    return result;
}

Calls tp_iternext. If it returns NULL without setting an exception, it sets StopIteration.

gopy notes

The gopy equivalent is objects/protocol.go and the vm/ call sites. PyObject_Call maps to vm.Call; attribute access maps to objects.GetAttr. The PyNumber_* family maps to the objects/object.go binary-op dispatch using Go interface assertions on py.Object.