Use dummy class to get TypeVar-like types

JelleZijlstra · JelleZijlstra · commit fdd887763333 · 2023-04-22T10:36:48.000-06:00
diff --git a/Lib/typing.py b/Lib/typing.py
@@ -1302,12 +1302,17 @@ def __typing_prepare_subst__(self, alias, args):
 
 import builtins
 if hasattr(builtins, "TypeVar"):
-    TypeVar = builtins.TypeVar
-    TypeVarTuple = builtins.TypeVarTuple
-    ParamSpec = builtins.ParamSpec
+    class _Dummy[T, *Ts, **P]:
+        type_params = (T, Ts, P)
+
+    TypeVar = type(_Dummy.type_params[0])
+    TypeVarTuple = type(_Dummy.type_params[1])
+    ParamSpec = type(_Dummy.type_params[2])
     ParamSpecArgs = type(ParamSpec("P").args)
     ParamSpecKwargs = type(ParamSpec("P").kwargs)
 
+    del _Dummy
+
     import copyreg
 
     def _pickle_psargs(psargs):
