Python/abstract.c

cpython 3.14 @ ab2d84fe1023/Python/abstract.c ↗

Python/abstract.c implements the abstract object API declared in Include/abstract.h. These are the C-level entry points for object operations that dispatch through Python's type slots (tp_as_sequence, tp_as_mapping, nb_add, etc.).

Map

Lines	Symbol	Role
1-300	PyObject_Call, _PyObject_CallMethodId	Generic callable dispatch
301-700	PyObject_GetItem, PyObject_SetItem, PyObject_DelItem	Subscript protocol
701-1100	PySequence_*	Sequence length, concatenation, repeat, contains
1101-1500	PyMapping_*	Mapping keys/values/items, has_key
1501-2800	PyNumber_*	Arithmetic, bitwise, unary through number slots

Reading

PyObject_Call

PyObject_Call(callable, args, kwargs) checks for tp_call or tp_vectorcall and dispatches. It is the C equivalent of calling callable(*args, **kwargs).

// CPython: Python/abstract.c:202 PyObject_Call
PyObject *
PyObject_Call(PyObject *callable, PyObject *args, PyObject *kwargs)
{
    ...
    vectorcallfunc func = _PyVectorcall_Function(callable);
    if (func != NULL) {
        return _PyVectorcall_Call(func, callable, args, kwargs);
    }
    ternaryfunc call = Py_TYPE(callable)->tp_call;
    if (call != NULL) {
        return call(callable, args, kwargs);
    }
    ...
}

PyObject_GetItem

PyObject_GetItem(obj, key) tries tp_as_mapping->mp_subscript first, then tp_as_sequence->sq_item (converting the key to an integer). This means a class can support both mapping and sequence subscript.

PyNumber_Add coercion

PyNumber_Add(a, b) tries a.__add__(b) first, then b.__radd__(a) if the first returns NotImplemented. If both fail, TypeError is raised. This dispatch is done by the binary_op1 helper shared by all binary numeric operators.

PySequence_Contains

PySequence_Contains(seq, ob) calls sq_contains if defined, or falls back to iterating the sequence and comparing with PyObject_RichCompareBool(item, ob, Py_EQ).

gopy notes

objects/protocol.go implements the abstract protocol functions for gopy. PyObject_Call maps to py.Call. PyObject_GetItem maps to py.GetItem. The number slot dispatch in PyNumber_Add is replicated in vm/eval_simple.go for BINARY_OP.