Objects/object.c (part 2)

Source:

cpython 3.14 @ ab2d84fe1023/Objects/object.c

This annotation covers string conversion of objects. See objects_object_detail for Py_INCREF/Py_DECREF, reference counting, PyObject_RichCompare, and PyObject_Hash.

Map

Lines	Symbol	Role
1-80	`PyObject_Repr`	`repr(obj)` — calls `__repr__`
81-160	`PyObject_Str`	`str(obj)` — calls `__str__`
161-240	`PyObject_ASCII`	`ascii(obj)` — repr with non-ASCII escaped
241-360	`PyObject_Bytes`	`bytes(obj)` — calls `__bytes__`
361-500	`PyObject_Format`	`format(obj, fmt_spec)`

Reading

`PyObject_Repr`

// CPython: Objects/object.c:480 PyObject_Repr
PyObject *
PyObject_Repr(PyObject *v)
{
    if (v == NULL) return PyUnicode_FromString("<NULL>");
    if (Py_TYPE(v)->tp_repr == NULL)
        return PyUnicode_FromFormat("<%s object at %p>",
                                    Py_TYPE(v)->tp_name, v);
    res = (*Py_TYPE(v)->tp_repr)(v);
    if (res == NULL) return NULL;
    if (!PyUnicode_Check(res)) {
        PyErr_Format(PyExc_TypeError,
                     "__repr__ returned non-string (type %.200s)",
                     Py_TYPE(res)->tp_name);
        Py_DECREF(res);
        return NULL;
    }
    return res;
}

repr(obj) calls tp_repr. If tp_repr is NULL, the fallback gives <ClassName object at 0x...>. The result must be a str; returning a non-string from __repr__ raises TypeError.

`PyObject_Str`

// CPython: Objects/object.c:540 PyObject_Str
PyObject *
PyObject_Str(PyObject *v)
{
    if (v == NULL) return PyUnicode_FromString("<NULL>");
    if (PyErr_CheckSignals()) return NULL;
    if (PyUnicode_CheckExact(v)) {
        Py_INCREF(v);
        return v;  /* Fast path: str(s) == s */
    }
    if (Py_TYPE(v)->tp_str == NULL)
        return PyObject_Repr(v);  /* Default: use repr */
    res = (*Py_TYPE(v)->tp_str)(v);
    ...
}

str(s) where s is already a str is a no-op (returns the same object). If tp_str is not defined, tp_repr is used as the fallback.

`PyObject_ASCII`

// CPython: Objects/object.c:600 PyObject_ASCII
PyObject *
PyObject_ASCII(PyObject *v)
{
    PyObject *repr = PyObject_Repr(v);
    /* Escape all non-ASCII characters */
    return _PyUnicode_TransformDecimalAndSpaceToASCII(repr);
}

ascii(obj) calls repr(obj) then escapes any non-ASCII code points as \xNN, \uNNNN, or \UNNNNNNNN. Useful for producing output safe for ASCII-only terminals.

`PyObject_Bytes`

// CPython: Objects/object.c:640 PyObject_Bytes
PyObject *
PyObject_Bytes(PyObject *v)
{
    if (v == NULL) return PyBytes_FromString("");
    if (PyBytes_CheckExact(v)) {
        Py_INCREF(v);
        return v;
    }
    /* Look for __bytes__ */
    PyObject *func = _PyObject_LookupSpecial(v, &_Py_ID(__bytes__));
    if (func != NULL) {
        PyObject *res = PyObject_CallNoArgs(func);
        Py_DECREF(func);
        return res;
    }
    /* Fall back to __index__ for integers */
    ...
}

bytes(n) where n is an integer creates a zero-filled bytes object of length n. bytes(obj) where obj has __bytes__ calls it. bytes([1,2,3]) creates b'\x01\x02\x03'.

`PyObject_Format`

// CPython: Objects/object.c:680 PyObject_Format
PyObject *
PyObject_Format(PyObject *obj, PyObject *format_spec)
{
    PyObject *func = _PyObject_LookupSpecial(obj, &_Py_ID(__format__));
    if (func == NULL) {
        /* Default: use str(obj) and check format_spec is empty */
        ...
    }
    return PyObject_CallOneArg(func, format_spec);
}

format(value, '>10') calls value.__format__('>10'). The default object.__format__ converts to string and raises if format_spec is non-empty for types without custom formatting.

gopy notes

PyObject_Repr is objects.Repr in objects/object.go. PyObject_Str is objects.Str. PyObject_ASCII calls objects.Repr then escapes via strconv.QuoteToASCII. PyObject_Bytes calls __bytes__ via objects.LookupSpecial. PyObject_Format calls __format__.

Map​

Reading​

PyObject_Repr​

PyObject_Str​

PyObject_ASCII​

PyObject_Bytes​

PyObject_Format​

gopy notes​

Map