8000 bpo-44676: Add ability to serialize types.Union (GH-27244) · python/cpython@fe13f0b · GitHub
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bpo-44676: Add ability to serialize types.Union (GH-27244)
1 parent 7d25254 commit fe13f0b

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4 files changed

+90
-2
lines changed

4 files changed

+90
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‎Lib/test/test_types.py

Lines changed: 35 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,9 @@
1313
import weakref
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import typing
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16+
17+
T = typing.TypeVar("T")
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1619
class Example:
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pass
1821

@@ -802,6 +805,38 @@ def eq(actual, expected):
802805
eq(x[NT], int | NT | bytes)
803806
eq(x[S], int | S | bytes)
804807

808+
def test_union_pickle(self):
809+
alias = list[T] | int
810+
s = pickle.dumps(alias)
811+
loaded = pickle.loads(s)
812+
self.assertEqual(alias, loaded)
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self.assertEqual(alias.__args__, loaded.__args__)
814+
self.assertEqual(alias.__parameters__, loaded.__parameters__)
815+
816+
def test_union_from_args(self):
817+
with self.assertRaisesRegex(
818+
TypeError,
819+
r"^Each union argument must be a type, got 1$",
820+
):
821+
types.Union._from_args((1,))
822+
823+
with self.assertRaisesRegex(
824+
TypeError,
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r"Union._from_args\(\) argument 'args' must be tuple, not int$",
826+
):
827+
types.Union._from_args(1)
828+
829+
with self.assertRaisesRegex(ValueError, r"args must be not empty"):
830+
types.Union._from_args(())
831+
832+
alias = types.Union._from_args((int, str, T))
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834+
self.assertEqual(alias.__args__, (int, str, T))
835+
self.assertEqual(alias.__parameters__, (T,))
836+
837+
result = types.Union._from_args((int,))
838+
self.assertIs(int, result)
839+
805840
def test_union_parameter_substitution_errors(self):
806841
T = typing.TypeVar("T")
807842
x = int | T

‎Lib/typing.py

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -329,7 +329,7 @@ def _eval_type(t, globalns, localns, recursive_guard=frozenset()):
329329
if isinstance(t, GenericAlias):
330330
return GenericAlias(t.__origin__, ev_args)
331331
if isinstance(t, types.Union):
332-
return functools.reduce(operator.or_, ev_args)
332+
return types.Union._from_args(ev_args)
333333
else:
334334
return t.copy_with(ev_args)
335335
return t
@@ -1808,7 +1808,7 @@ def _strip_annotations(t):
18081808
stripped_args = tuple(_strip_annotations(a) for a in t.__args__)
18091809
if stripped_args == t.__args__:
18101810
return t
1811-
return functools.reduce(operator.or_, stripped_args)
1811+
return types.Union._from_args(stripped_args)
18121812

18131813
return t
18141814

‎Misc/NEWS.d/next/Core and Builtins/2021-07-19-19-53-46.bpo-44676.WgIMvh.rst

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,2 @@
1+
Add ability to serialise ``types.Union`` objects. Patch provided by Yurii
2+
Karabas.

‎Objects/unionobject.c

Lines changed: 51 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -299,6 +299,24 @@ is_unionable(PyObject *obj)
299299
return 0;
300300
}
301301

302+
static int
303+
is_args_unionable(PyObject *args)
304+
{
305+
Py_ssize_t nargs = PyTuple_GET_SIZE(args);
306+
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
307+
PyObject *arg = PyTuple_GET_ITEM(args, iarg);
308+
int is_arg_unionable = is_unionable(arg);
309+
if (is_arg_unionable <= 0) {
310+
if (is_arg_unionable == 0) {
311+
PyErr_Format(PyExc_TypeError,
312+
"Each union argument must be a type, got %.100R", arg);
313+
}
314+
return 0;
315+
}
316+
}
317+
return 1;
318+
}
319+
302320
PyObject *
303321
_Py_union_type_or(PyObject* self, PyObject* other)
304322
{
@@ -418,14 +436,47 @@ union_repr(PyObject *self)
418436
return NULL;
419437
}
420438

439+
static PyObject *
440+
union_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
441+
{
442+
unionobject *alias = (unionobject *)self;
443+
PyObject* from_args = PyObject_GetAttrString(self, "_from_args");
444+
if (from_args == NULL) {
445+
return NULL;
446+
}
447+
448+
return Py_BuildValue("O(O)", from_args, alias->args);
449+
}
450+
421451
static PyMemberDef union_members[] = {
422452
{"__args__", T_OBJECT, offsetof(unionobject, args), READONLY},
423453
{0}
424454
};
425455

456+
static PyObject *
457+
union_from_args(PyObject *cls, PyObject *args)
458+
{
459+
if (!PyTuple_CheckExact(args)) {
460+
_PyArg_BadArgument("Union._from_args", "argument 'args'", "tuple", args);
461+
return NULL;
462+
}
463+
if (!PyTuple_GET_SIZE(args)) {
464+
PyErr_SetString(PyExc_ValueError, "args must be not empty");
465+
return NULL;
466+
}
467+
468+
if (is_args_unionable(args) <= 0) {
469+
return NULL;
470+
}
471+
472+
return make_union(args);
473+
}
474+
426475
static PyMethodDef union_methods[] = {
476+
{"_from_args", union_from_args, METH_O | METH_CLASS},
427477
{"__instancecheck__", union_instancecheck, METH_O},
428478
{"__subclasscheck__", union_subclasscheck, METH_O},
479+
{"__reduce__", union_reduce, METH_NOARGS},
429480
{0}};
430481

431482

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