Objects/moduleobject.c (part 4)

Source:

cpython 3.14 @ ab2d84fe1023/Objects/moduleobject.c ↗

This annotation covers module metadata and multi-phase initialization. See objects_moduleobject3_detail for module.__init__, __getattr__, __dir__, and module.__dict__.

Map

Lines	Symbol	Role
1-80	module.__repr__	<module 'name' from 'path'>
81-160	PyModuleDef	C struct for multi-phase init
161-240	Multi-phase init	Py_mod_exec slot in PyModuleDef
241-320	Module __spec__ / __loader__	Import system metadata attributes
321-500	sys.modules lifecycle	How modules are installed and unloaded

Reading

module.__repr__

// CPython: Objects/moduleobject.c:640 module_repr
static PyObject *
module_repr(PyModuleObject *m)
{
    PyObject *name = PyObject_GetAttrString((PyObject *)m, "__name__");
    PyObject *filename = PyObject_GetAttrString((PyObject *)m, "__file__");
    if (filename != NULL) {
        return PyUnicode_FromFormat("<module %R from %R>", name, filename);
    }
    PyErr_Clear();
    PyObject *spec = PyObject_GetAttrString((PyObject *)m, "__spec__");
    if (spec != NULL) {
        return PyObject_CallMethodOneArg(spec, &_Py_ID(_repr_), (PyObject *)m);
    }
    return PyUnicode_FromFormat("<module %R (built-in)>", name);
}

The repr prefers __file__ (file-based modules). Without a file, it delegates to __spec__._repr_(m) which knows the module's origin (frozen, namespace, etc.). Built-in modules show (built-in).

PyModuleDef multi-phase init

// CPython: Objects/moduleobject.c:120 PyModule_FromDefAndSpec2
PyObject *
PyModule_FromDefAndSpec2(PyModuleDef *def, PyObject *spec, int module_api_version)
{
    /* Phase 1: create the module object */
    PyObject *mod = PyModule_NewObject(name);
    mod->md_def = def;
    /* Run Py_mod_create slot if present */
    if (def->m_slots) {
        for (PyModuleDef_Slot *slot = def->m_slots; slot->slot; slot++) {
            if (slot->slot == Py_mod_create)
                mod = ((create_fn)slot->value)(spec, def);
        }
    }
    return mod;
}

Multi-phase init (PEP 451) separates module creation (Py_mod_create) from module execution (Py_mod_exec). This allows the module object to be installed in sys.modules before its code runs, enabling circular imports between C extensions and Python modules.

__spec__ attributes

# CPython: Lib/importlib/_bootstrap.py:560 ModuleSpec
class ModuleSpec:
    def __init__(self, name, loader, *, origin=None, loader_state=None,
                 is_package=None):
        self.name = name
        self.loader = loader
        self.origin = origin     # Typically __file__
        self.submodule_search_locations = [] if is_package else None
        # __path__ = submodule_search_locations for packages

module.__spec__ is a ModuleSpec set by the import system. It contains name, loader, origin (file path), and submodule_search_locations (__path__ for packages). After import, the module's __file__, __loader__, __package__, and __path__ are derived from __spec__.

gopy notes

module.__repr__ is objects.ModuleRepr in objects/module.go. Multi-phase init is not yet implemented in gopy. ModuleSpec is objects.ModuleSpec. Module metadata (__spec__, __loader__, __file__) are set in vm/eval_import.go after exec_module completes.