Sep 26, 2024 · May 21, 2024 · May 21, 2024 · May 21, 2024 · May 21, 2024 · May 21, 2024
diff --git a/Lib/functools.py b/Lib/functools.py
    Used as a placeholder for partial arguments.
    """
    __instance = None
    __slots__ = ()

    def __new__(cls):
        if cls.__instance is None:
    def __reduce__(self):
        return 'Placeholder'

 def __placeholder_init_subclass__(cls, *args, **kwargs):
    raise TypeError(f"type '{cls.__name__}' is not an acceptable base type")

 Placeholder = type('PlaceholderType', (__PlaceholderTypeBase,), {})()
 Placeholder = type(
    'PlaceholderType',
    (__PlaceholderTypeBase,),
    {'__slots__': (), '__init_subclass__': __placeholder_init_subclass__}
 )()


 def _partial_prepare_new(cls, func, args, keywords):
diff --git a/Lib/pickle.py b/Lib/pickle.py
 from copyreg import dispatch_table
 from copyreg import _extension_registry, _inverted_registry, _extension_cache
 from itertools import islice
 from functools import partial
 from functools import partial, Placeholder
 import sys
 from sys import maxsize
 from struct import pack, unpack
            return self.save_reduce(type, (NotImplemented,), obj=obj)
        elif obj is type(...):
            return self.save_reduce(type, (...,), obj=obj)
        elif obj is type(Placeholder):
            return self.save_reduce(type, (Placeholder,), obj=obj)
        return self.save_global(obj)

    dispatch[FunctionType] = save_global
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
    return PyUnicode_FromString("Placeholder");
 }

 static PyObject *
 placeholder_reduce(PyObject *op, PyObject *Py_UNUSED(ignored))
 {
    return PyUnicode_FromString("Placeholder");
 }

 static PyMethodDef placeholder_methods[] = {
    {"__reduce__", placeholder_reduce, METH_NOARGS, NULL},
    {NULL, NULL}
 };

 static void
 placeholder_dealloc(PyObject* placeholder)
 {
    {Py_tp_dealloc, placeholder_dealloc},
    {Py_tp_repr, placeholder_repr},
    {Py_tp_doc, (void *)placeholder_doc},
    {Py_tp_methods, placeholder_methods},
    {Py_tp_new, placeholder_new},
    // Number protocol
    {Py_nb_bool, placeholder_bool},
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
    /* functools.partial, used for implementing __newobj_ex__ with protocols
       2 and 3 */
    PyObject *partial;
    PyObject *placeholder;

    /* Types */
    PyTypeObject *Pickler_Type;
    Py_CLEAR(st->codecs_encode);
    Py_CLEAR(st->getattr);
    Py_CLEAR(st->partial);
    Py_CLEAR(st->placeholder);
    Py_CLEAR(st->Pickler_Type);
    Py_CLEAR(st->Unpickler_Type);
    Py_CLEAR(st->Pdata_Type);
    st->partial = _PyImport_GetModuleAttrString("functools", "partial");
    if (!st->partial)
        goto error;
    st->placeholder = _PyImport_GetModuleAttrString("functools", "Placeholder");
    if (!st->placeholder)
        goto error;

    return 0;

    else if (obj == (PyObject *)&_PyNotImplemented_Type) {
        return save_singleton_type(state, self, obj, Py_NotImplemented);
    }
    else if (obj == (PyObject *)Py_TYPE(state->placeholder)) {
        return save_singleton_type(state, self, obj, state->placeholder);
    }
    return save_global(state, self, obj, NULL);
 }

    Py_VISIT(st->codecs_encode);
    Py_VISIT(st->getattr);
    Py_VISIT(st->partial);
    Py_VISIT(st->placeholder);
    Py_VISIT(st->Pickler_Type);
    Py_VISIT(st->Unpickler_Type);
    Py_VISIT(st->Pdata_Type);
Original file line number	Diff line number	Diff line change
Expand Up		@@ -280,6 +280,7 @@ class __PlaceholderTypeBase:
		Used as a placeholder for partial arguments.
		"""
		__instance = None
dg-pb marked this conversation as resolved. Show resolvedHide resolved
		__slots__ = ()

		def __new__(cls):
		if cls.__instance is None:
Expand All		@@ -295,8 +296,14 @@ def __repr__(self):
		def __reduce__(self):
		return 'Placeholder'

		def __placeholder_init_subclass__(cls, args, *kwargs):
		raise TypeError(f"type '{cls.__name__}' is not an acceptable base type")

		Placeholder = type('PlaceholderType', (__PlaceholderTypeBase,), {})()
		Placeholder = type(
		'PlaceholderType',
		(__PlaceholderTypeBase,),
		{'__slots__': (), '__init_subclass__': __placeholder_init_subclass__}
		)()

dg-pb marked this conversation as resolved. OutdatedShow resolvedHide resolved

		def _partial_prepare_new(cls, func, args, keywords):
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -27,7 +27,7 @@
		from copyreg import dispatch_table
		from copyreg import _extension_registry, _inverted_registry, _extension_cache
		from itertools import islice
		from functools import partial
		from functools import partial, Placeholder
		import sys
		from sys import maxsize
		from struct import pack, unpack
Expand DownExpand Up		@@ -1120,6 +1120,8 @@ def save_type(self, obj):
		return self.save_reduce(type, (NotImplemented,), obj=obj)
		elif obj is type(...):
		return self.save_reduce(type, (...,), obj=obj)
		elif obj is type(Placeholder):
		return self.save_reduce(type, (Placeholder,), obj=obj)
		return self.save_global(obj)

		dispatch[FunctionType] = save_global
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -63,6 +63,17 @@ placeholder_repr(PyObject *op)
		return PyUnicode_FromString("Placeholder");
Copy link Member picnixzAug 12, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Maybe use`functools.Placeholder` instead actually? The singleton is really tight to the functools module and is not just a universal one. So I think it's closer to what`typing.NoDefault` is. In particular, you could also decide whether the singleton should be implemented (and exported) using the same logic as for`typing.NoDefault` or if it should be done as for`None` and other global singletons. (Sorry, I only remembered about that singleton now and not before)
		}

		static PyObject *
		placeholder_reduce(PyObject op, PyObject Py_UNUSED(ignored))
		{
		return PyUnicode_FromString("Placeholder");
		}

		static PyMethodDef placeholder_methods[] = {
		{"__reduce__", placeholder_reduce, METH_NOARGS, NULL},
		{NULL, NULL}
		};

		static void
		placeholder_dealloc(PyObject* placeholder)
		{
Expand DownExpand Up		@@ -98,6 +109,7 @@ static PyType_Slot placeholder_type_slots[] = {
		{Py_tp_dealloc, placeholder_dealloc},
		{Py_tp_repr, placeholder_repr},
		{Py_tp_doc, (void *)placeholder_doc},
		{Py_tp_methods, placeholder_methods},
		{Py_tp_new, placeholder_new},
		// Number protocol
		{Py_nb_bool, placeholder_bool},
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -198,6 +198,7 @@ typedef struct {
		/* functools.partial, used for implementing __newobj_ex__ with protocols
		2 and 3 */
		PyObject *partial;
		PyObject *placeholder;

		/* Types */
		PyTypeObject *Pickler_Type;
Expand DownExpand Up		@@ -253,6 +254,7 @@ _Pickle_ClearState(PickleState *st)
		Py_CLEAR(st->codecs_encode);
		Py_CLEAR(st->getattr);
		Py_CLEAR(st->partial);
		Py_CLEAR(st->placeholder);
		Py_CLEAR(st->Pickler_Type);
		Py_CLEAR(st->Unpickler_Type);
		Py_CLEAR(st->Pdata_Type);
Expand DownExpand Up		@@ -375,6 +377,9 @@ _Pickle_InitState(PickleState *st)
		st->partial = _PyImport_GetModuleAttrString("functools", "partial");
		if (!st->partial)
		goto error;
		st->placeholder = _PyImport_GetModuleAttrString("functools", "Placeholder");
		if (!st->placeholder)
		goto error;

		return 0;

Expand DownExpand Up		@@ -3861,6 +3866,9 @@ save_type(PickleState state, PicklerObject self, PyObject *obj)
		else if (obj == (PyObject *)&_PyNotImplemented_Type) {
		return save_singleton_type(state, self, obj, Py_NotImplemented);
		}
		else if (obj == (PyObject *)Py_TYPE(state->placeholder)) {
		return save_singleton_type(state, self, obj, state->placeholder);
		}
		return save_global(state, self, obj, NULL);
		}

Expand DownExpand Up		@@ -7791,6 +7799,7 @@ pickle_traverse(PyObject m, visitproc visit, void arg)
		Py_VISIT(st->codecs_encode);
		Py_VISIT(st->getattr);
		Py_VISIT(st->partial);
		Py_VISIT(st->placeholder);
		Py_VISIT(st->Pickler_Type);
		Py_VISIT(st->Unpickler_Type);
		Py_VISIT(st->Pdata_Type);
Expand Down