obj.attr

>>> def example():
...     obj.attr
...
>>> import dis
>>> dis.dis(example)
  2           0 LOAD_GLOBAL              0 (obj)
              2 LOAD_ATTR                1 (attr)
              4 POP_TOP
              6 LOAD_CONST               0 (None)
              8 RETURN_VALUE

case TARGET(LOAD_ATTR): {
            PyObject *name = GETITEM(names, oparg);
            PyObject *owner = TOP();
            PyObject *res = PyObject_GetAttr(owner, name);
            Py_DECREF(owner);
            SET_TOP(res);
            if (res == NULL)
                goto error;
            DISPATCH();
        }

static PyObject *
builtin_getattr(PyObject *self, PyObject *const *args, Py_ssize_t nargs)
{
    PyObject *v, *name, *result;
    if (!_PyArg_CheckPositional("getattr", nargs, 2, 3))
        return NULL;
    v = args[0];
    name = args[1];
    if (!PyUnicode_Check(name)) {
        PyErr_SetString(PyExc_TypeError,
                        "getattr(): attribute name must be string");
        return NULL;
    }
    if (nargs > 2) {
        if (_PyObject_LookupAttr(v, name, &result) == 0) {
            PyObject *dflt = args[2];
            Py_INCREF(dflt);
            return dflt;
        }
    }
    else {
        result = PyObject_GetAttr(v, name);
    }
    return result;
}

def getattr(obj: Any, attr: str, default: Any) -> Any:
    if not isinstance(attr, str):
        raise TypeError("getattr(): attribute name must be string")
    ...  # Fill in with PyObject_GetAttr().

# Based on https://github.com/python/cpython/tree/v3.8.3.
from __future__ import annotations
import builtins
NOTHING = builtins.object()  # C: NULL
def getattr(obj: Any, attr: str, default: Any = NOTHING) -> Any:
    """Implement attribute access via  __getattribute__ and __getattr__."""
    # Python/bltinmodule.c:builtin_getattr
    if not isinstance(attr, str):
        raise TypeError("getattr(): attribute name must be string")
    obj_type_mro = type(obj).mro()
    attr_exc = NOTHING
    for base in obj_type_mro:
        if "__getattribute__" in base.__dict__:
            try:
                return base.__dict__["__getattribute__"](obj, attr)
            except AttributeError as exc:
                attr_exc = exc
                break
    # Objects/typeobject.c:slot_tp_getattr_hook
    # It is cheating to do this here as CPython actually rebinds the tp_getattro
    # slot with a wrapper that handles __getattr__() when present.
    for base in obj_type_mro:
        if "__getattr__" in base.__dict__:
            return base.__dict__["__getattr__"](obj, attr)
    if default is not NOTHING:
        return default
    elif attr_exc is not NOTHING:
        raise attr_exc
    else:
        raise AttributeError(f"{self.__name__!r} object has no attribute {attr!r}")

def _mro_getattr(type_: Type, attr: str) -> Any:
    """Get an attribute from a type based on its MRO."""
    for base in type_.mro():
        if attr in base.__dict__:
            return base.__dict__[attr]
    else:
        raise AttributeError(f"{type_.__name__!r} object has no attribute {attr!r}")
class object:
    def __getattribute__(self, attr: str, /) -> Any:
        """Attribute access."""
        # Objects/object.c:PyObject_GenericGetAttr
        self_type = type(self)
        if not isinstance(attr, str):
            raise TypeError(
                f"attribute name must be string, not {type(attr).__name__!r}"
            )
        type_attr = descriptor_type_get = NOTHING
        try:
            type_attr = _mro_getattr(self_type, attr)
        except AttributeError:
            pass  # Hopefully an instance attribute.
        else:
            type_attr_type = type(type_attr)
            try:
                descriptor_type_get = _mro_getattr(type_attr_type, "__get__")
            except AttributeError:
                pass  # At least a class attribute.
            else:
                # At least a non-data descriptor.
                for base in type_attr_type.mro():
                    if "__set__" in base.__dict__ or "__delete__" in base.__dict__:
                        # Data descriptor.
                        return descriptor_type_get(type_attr, self, self_type)
        if attr in self.__dict__:
            # Instance attribute.
            return self.__dict__[attr]
        elif descriptor_type_get is not NOTHING:
            # Non-data descriptor.
            return descriptor_type_get(type_attr, self, self_type)
        elif type_attr is not NOTHING:
            # Class attribute.
            return type_attr
        else:
            raise AttributeError(f"{self.__name__!r} object has no attribute {attr!r}")