example

python/examples/python-types-at-pyweb-2024-12/generics_two_types.py

@@ -1,6 +1,30 @@
-def the_same[T](x: T, y: T) -> None:
-    print(x, y)
+
+def no_problem[T](x: T, y: T) -> None:
+    print(type(x).__name__, type(y).__name__)
+
+no_problem(2, 2)
+no_problem("hi", "hi")
+no_problem("hi", 2)
+
+# -----------------------------
+from typing import TypeVar
+
+T = TypeVar('T', int, str)
+
+def the_same(x: T, y: T) -> None:
+    print(type(x).__name__, type(y).__name__)
 
 the_same(2, 2)
 the_same("hi", "hi")
 the_same("hi", 2)
+
+
+# -----------------------------
+Q = TypeVar('Q', int, str)
+
+def different(x: T, y: Q) -> None:
+    print(type(x).__name__, type(y).__name__)
+
+different(2, 2)
+different("hi", "hi")
+different("hi", 2)

python/python-types-at-pyweb-2024-12.md

@@ -231,6 +231,17 @@ Found 1 error in 1 file (checked 1 source file)
 
 ![](examples/python-types-at-pyweb-2024-12/generics.py)
 
+## Two variables of the same and different types
+{id: python-types-at-pyweb-2024-12-same-and-different-types}
+
+![](examples/python-types-at-pyweb-2024-12/generics_two_types.py)
+
+```
+$ mypy generics_two_types.py
+generics_two_types.py:10:1: error: Value of type variable "T" of "the_same" cannot be "object"  [type-var]
+Found 1 error in 1 file (checked 1 source file)
+```
+
 ## mypy suggestions
 {id: python-types-at-pyweb-2024-12-mypy-suggestions}
 
@@ -301,11 +312,4 @@ Found 1 error in 1 file (checked 1 source file)
 ```
 
 
-## Two variables of the same and different types
-{id: python-types-at-pyweb-2024-12-same-and-different-types}
-
-TODO: Why is mypy accepting this?
-
-![](examples/python-types-at-pyweb-2024-12/generics_two_types.py)
-