Final QA

python-313/replace.py

@@ -21,3 +21,38 @@ class Person(NamedTuple):
 person = Person(name="Geir Arne", place="Oslo", version="3.12")
 print(copy.replace(person, version="3.13"))
 print(copy.replace(today, day=1))
+
+
+# %% Create a custom class that supports copy.replace()
+class NamedContainer:
+    def __init__(self, name, **items):
+        print(f"Initializing {name} with {items}")
+        self.name = name
+        self.items = items
+
+    def __replace__(self, **kwargs):
+        """.__replace__() is called by copy.replace()"""
+        if "name" in kwargs:
+            raise ValueError("'name' can't be updated")
+
+        print(f"Replacing {kwargs} in {self.name}")
+        init_kwargs = {"name": self.name} | self.items | kwargs
+
+        # Create a new object with updated arguments
+        cls = type(self)
+        return cls(**init_kwargs)
+
+    def __repr__(self):
+        items = [f"{key}={value!r}" for key, value in self.items.items()]
+        return f"{type(self).__name__}(name='{self.name}', {", ".join(items)})"
+
+
+capitals = NamedContainer(
+    "capitals", norway="oslo", sweden="Stockholm", denmark="Copenhagen"
+)
+print(f"{capitals = }")
+
+capitals = copy.replace(capitals, norway="Oslo")
+print(f"{capitals = }")
+
+# copy.replace(capitals, name="Scandinavia")  # Raises an error, name can't be replaced

python-313/typing/tree.py

@@ -4,7 +4,9 @@
 
 
 def is_tree(obj: object) -> TypeGuard[Tree]:
-    return isinstance(obj, list)
+    return isinstance(obj, list) and all(
+        is_tree(elem) or isinstance(elem, int) for elem in obj
+    )
 
 
 def get_left_leaf_value(tree_or_leaf: Tree | int) -> int:
@@ -21,7 +23,9 @@ def get_left_leaf_value(tree_or_leaf: Tree | int) -> int:
 # type Tree = list[Tree | int]
 #
 # def is_tree(obj: object) -> TypeIs[Tree]:
-#     return isinstance(obj, list)
+#     return isinstance(obj, list) and all(
+#         is_tree(elem) or isinstance(elem, int) for elem in obj
+#     )
 #
 # def get_left_leaf_value(tree_or_leaf: Tree | int) -> int:
 #     if is_tree(tree_or_leaf):