Objects/funcobject.c (part 3)

Source:

cpython 3.14 @ ab2d84fe1023/Objects/funcobject.c ↗

This annotation covers the function object's attributes. See objects_function2_detail for PyFunction_New, func_call, __defaults__, and closure variables.

Map

Lines	Symbol	Role
1-80	PyFunctionObject fields	func_code, func_globals, func_defaults, etc.
81-160	func_version	Cache invalidation tag for CALL specialization
161-240	func.__annotations__	PEP 3107 parameter and return annotations
241-320	func.__kwdefaults__	Default values for keyword-only parameters
321-500	func.__wrapped__	Reference to the wrapped function (for functools.wraps)

Reading

PyFunctionObject fields

// CPython: Objects/funcobject.c:20 PyFunctionObject
struct PyFunctionObject {
    PyObject_HEAD
    PyObject *func_code;       /* PyCodeObject */
    PyObject *func_globals;    /* module __dict__ */
    PyObject *func_defaults;   /* tuple of positional defaults or NULL */
    PyObject *func_kwdefaults; /* dict of keyword-only defaults or NULL */
    PyObject *func_closure;    /* tuple of cells or NULL */
    PyObject *func_doc;        /* __doc__ */
    PyObject *func_name;       /* __name__ */
    PyObject *func_dict;       /* __dict__ */
    PyObject *func_weakreflist;
    PyObject *func_module;     /* __module__ */
    PyObject *func_annotations;/* __annotations__: dict or NULL */
    PyObject *func_typeparams; /* PEP 695 type params */
    vectorcallfunc vectorcall;
    uint32_t func_version;
};

func_globals is the module's __dict__ at definition time. Global variable lookups in the function use this dict. func_closure contains the cells shared with enclosing scopes.

func_version

// CPython: Objects/funcobject.c:180 _PyFunction_SetVersion
void
_PyFunction_SetVersion(PyFunctionObject *func, uint32_t version)
{
    func->func_version = version;
    /* Cache version in the first instruction's cache */
    _Py_SET_OPCODE_CACHE((_Py_CODEUNIT *)PyBytes_AS_STRING(func->func_code->co_code),
                         version);
}

func_version is set when a function is created and invalidated when __defaults__, __code__, or other cached attributes change. CALL_PY_EXACT_ARGS checks the version to ensure its cached co_argcount is still valid.

func.__annotations__

// CPython: Objects/funcobject.c:580 func_get_annotations
static PyObject *
func_get_annotations(PyFunctionObject *op, void *Py_UNUSED(ignored))
{
    if (op->func_annotations == NULL) {
        op->func_annotations = PyDict_New();
    }
    if (PyTuple_Check(op->func_annotations)) {
        /* 3.14+ lazy annotation evaluation */
        return _PyFunction_GetAnnotationsDict(op);
    }
    return Py_NewRef(op->func_annotations);
}

In 3.14+, from __future__ import annotations stores annotations as a tuple of (name, value_expr) pairs for lazy evaluation. __annotations__ getter evaluates them on demand. Before 3.14, they were always eagerly evaluated.

gopy notes

PyFunctionObject fields map to objects.Function struct in objects/function.go. func_version is objects.Function.Version, incremented on modification. func.__annotations__ returns objects.Function.Annotations, lazily evaluated from the code object's annotation table.