Python/bltinmodule.c

Source:

cpython 3.14 @ ab2d84fe1023/Python/bltinmodule.c ↗

Python/bltinmodule.c implements the built-in functions that live in the builtins module. It is one of the first C files loaded at interpreter startup. The file contains print, len, type, isinstance, issubclass, getattr, setattr, hasattr, vars, dir, iter, next, map, zip, sorted, reversed, abs, round, divmod, pow, input, open, and others.

Map

Lines	Symbol	Role
1-200	builtin_print, builtin_input	Terminal I/O
201-500	builtin_len, builtin_abs, builtin_round	Numeric and size builtins
501-800	builtin_isinstance, builtin_issubclass	Type hierarchy checks
801-1100	builtin_getattr, builtin_setattr, builtin_hasattr, builtin_delattr	Attribute access
1101-1400	builtin_vars, builtin_dir, builtin_callable	Introspection
1401-1700	builtin_iter, builtin_next, builtin_sorted	Iterator protocol
1701-2200	builtin_map, builtin_zip, builtin_filter	Lazy sequence combinators
2201-3000	builtin_open, builtin_compile, builtin_exec, builtin_eval	I/O and code execution

Reading

isinstance and issubclass

builtin_isinstance(inst, cls) dispatches to PyObject_IsInstance. For a single type it calls PyType_IsSubtype. For a tuple of types it iterates and short-circuits on the first match. The __instancecheck__ and __subclasscheck__ hooks on the type's metaclass are respected.

// Python/bltinmodule.c:501 builtin_isinstance_impl
static PyObject *
builtin_isinstance_impl(PyObject *module, PyObject *obj, PyObject *class_or_tuple)
{
    int retval = PyObject_IsInstance(obj, class_or_tuple);
    if (retval < 0) return NULL;
    return PyBool_FromLong(retval);
}

getattr with default

getattr(obj, name) calls PyObject_GetAttr. The three-argument form getattr(obj, name, default) calls _PyObject_GetAttrWithoutError and returns default on AttributeError without setting an exception.

// Python/bltinmodule.c:801 builtin_getattr_impl
static PyObject *
builtin_getattr_impl(PyObject *module, PyObject *object,
                     PyObject *name, PyObject *default_value)
{
    if (default_value != NULL) {
        v = _PyObject_GetAttrWithoutError(object, name);
        if (v == NULL) { PyErr_Clear(); Py_INCREF(default_value); return default_value; }
        return v;
    }
    return PyObject_GetAttr(object, name);
}

open delegates to io.open

builtin_open calls PyObject_Call(io_open, args, kwargs) where io_open is the cached io.open callable loaded at module init. This means open() in Python calls the same code path as io.open().

gopy notes

The gopy built-in functions are partly in objects/ (for type-based ones like len, isinstance) and partly in the VM (vm/eval_call.go for call dispatch). The builtins module object is initialized in vm/eval_import.go or objects/module.go.