docs(frozen_dataclass): enhance doctests to demonstrate behavior before and after sealing

Author: tony

src/libtmux/_internal/frozen_dataclass_sealable.py

@@ -99,13 +99,39 @@ def mutable_during_init(
     ...         metadata={"mutable_during_init": True}
     ...     )
     >>> 
-    >>> # Create an instance
+    >>> # Create an instance with deferred sealing
     >>> example = Example(name="test-example")
     >>> 
-    >>> # Can modify mutable field
+    >>> # Cannot modify immutable fields even before sealing
+    >>> try:
+    ...     example.name = "new-name"
+    ... except AttributeError as e:
+    ...     print(f"Error: {type(e).__name__}")
+    Error: AttributeError
+    >>> 
+    >>> # Can modify mutable field before sealing
     >>> example.items.append("item1")
     >>> example.items
     ['item1']
+    >>> 
+    >>> # Now seal the object
+    >>> example.seal()
+    >>> 
+    >>> # Verify the object is sealed
+    >>> hasattr(example, "_sealed") and example._sealed
+    True
+    >>> 
+    >>> # Cannot modify mutable field after sealing
+    >>> try:
+    ...     example.items = ["new-item"]
+    ... except AttributeError as e:
+    ...     print(f"Error: {type(e).__name__}")
+    Error: AttributeError
+    >>> 
+    >>> # But can still modify the contents of mutable containers
+    >>> example.items.append("item2")
+    >>> example.items
+    ['item1', 'item2']
     """
     if field_method is None:
         # Used with parentheses: @mutable_during_init()
@@ -236,22 +262,39 @@ def frozen_dataclass_sealable(
     >>> # Cannot modify frozen field
     >>> try:
     ...     config.name = "modified"
-    ... except AttributeError:
-    ...     print("Cannot modify frozen field")
-    Cannot modify frozen field
+    ... except AttributeError as e:
+    ...     print(f"Error: {type(e).__name__}")
+    Error: AttributeError
     >>> 
-    >>> # Can modify mutable field
+    >>> # Can modify mutable field before sealing
     >>> config.values["key1"] = 100
     >>> config.values
     {'key1': 100}
     >>> 
+    >>> # Can also directly assign to mutable field before sealing
+    >>> new_values = {"key2": 200}
+    >>> config.values = new_values
+    >>> config.values
+    {'key2': 200}
+    >>> 
     >>> # Seal the object
     >>> config.seal()
     >>> 
-    >>> # Can still modify the contents of mutable containers after sealing
-    >>> config.values["key2"] = 200
+    >>> # Verify the object is sealed
+    >>> hasattr(config, "_sealed") and config._sealed
+    True
+    >>> 
+    >>> # Cannot modify mutable field after sealing
+    >>> try:
+    ...     config.values = {"key3": 300}
+    ... except AttributeError as e:
+    ...     print(f"Error: {type(e).__name__}")
+    Error: AttributeError
+    >>> 
+    >>> # But can still modify the contents of mutable containers after sealing
+    >>> config.values["key3"] = 300
     >>> config.values
-    {'key1': 100, 'key2': 200}
+    {'key2': 200, 'key3': 300}
 
     With deferred sealing:
     
@@ -266,6 +309,8 @@ def frozen_dataclass_sealable(
     >>> # Create a linked list
     >>> node1 = Node(value=1)  # Not sealed automatically
     >>> node2 = Node(value=2)  # Not sealed automatically
+    >>> 
+    >>> # Can modify mutable field before sealing
     >>> node1.next_node = node2
     >>> 
     >>> # Verify structure
@@ -285,6 +330,13 @@ def frozen_dataclass_sealable(
     True
     >>> hasattr(node2, "_sealed") and node2._sealed
     True
+    >>> 
+    >>> # Cannot modify mutable field after sealing
+    >>> try:
+    ...     node1.next_node = None
+    ... except AttributeError as e:
+    ...     print(f"Error: {type(e).__name__}")
+    Error: AttributeError
     """
     # Support both @frozen_dataclass_sealable and @frozen_dataclass_sealable() usage
     if cls is None: