Abandon attempts to support protocols in 3.5.0 and 3.5.1, see python#195

typing_extensions/src_py3/test_typing_extensions.py

@@ -11,7 +11,11 @@
 from typing import Generic
 from typing import get_type_hints
 from typing import no_type_check
-from typing_extensions import NoReturn, ClassVar, Type, NewType, Protocol, runtime
+from typing_extensions import NoReturn, ClassVar, Type, NewType
+try:
+    from typing_extensions import Protocol, runtime
+except ImportError:
+    pass
 import typing
 import typing_extensions
 import collections.abc as collections_abc
@@ -48,6 +52,10 @@
 # For checks reliant on Python 3.6 syntax changes (e.g. classvar)
 PY36 = sys.version_info[:2] >= (3, 6)
 
+# It is very difficult to backport Protocols to these versions due to
+# different generics system. See https://github.com/python/typing/pull/195
+NO_PROTOCOL = sys.version_info[:3] in [(3, 5, 0), (3, 5, 1)]
+
 
 class BaseTestCase(TestCase):
     def assertIsSubclass(self, cls, class_or_tuple, msg=None):
@@ -1087,6 +1095,10 @@ class E:
             self.assertIsInstance(E(), D)
 
 
+if NO_PROTOCOL:
+    ProtocolTests = None
+
+
 class AllTests(BaseTestCase):
     def test_typing_extensions_includes_standard(self):
         a = typing_extensions.__all__

typing_extensions/src_py3/typing_extensions.py

@@ -8,11 +8,12 @@
 # These are used by Protocol implementation
 # We use internal typing helpers here, but this significantly reduces
 # code duplication. (Also this is only until Protocol is in typing.)
-from typing import (
-    GenericMeta, TypingMeta, Generic, Callable, TypeVar, Tuple,
-    _type_vars, _next_in_mro, _type_check,
-    _make_subclasshook, _check_generic
-)
+from typing import GenericMeta, TypingMeta, Generic, Callable, TypeVar, Tuple
+NO_PROTOCOL = False
+try:
+    from typing import _type_vars, _next_in_mro, _type_check, _check_generic
+except ImportError:
+    NO_PROTOCOL = True
 try:
     from typing import _no_slots_copy
 except ImportError:
@@ -31,6 +32,10 @@ def _no_slots_copy(dct):
 except ImportError:
     class _TypingEllipsis: pass
     class _TypingEmpty: pass
+try:
+    from typing import _make_subclasshook
+except ImportError:
+    _make_subclasshook = None
 
 if hasattr(typing, '_generic_new'):
     _generic_new = typing._generic_new
@@ -908,3 +913,7 @@ def runtime(cls):
                         ' got %r' % cls)
     cls._is_runtime_protocol = True
     return cls
+
+
+if NO_PROTOCOL:
+    del Protocol, runtime