no copy

Author: willmcgugan

docs/guide/reactivity.md

@@ -410,7 +410,8 @@ Note the call to `mutate_reactive`. Without it, the display would not update whe
 
 ## Data binding
 
-Reactive attributes from one widget may be *bound* (connected) to another widget, so that changes to a single reactive will automatically update another widget (potentially more than one).
+Reactive attributes may be *bound* (connected) to attributes on child widgets, so that changes to the parent are automatically reflected in the children.
+This can simplify working with compound widgets where the value of an attribute might be used in multiple places.
 
 To bind reactive attributes, call [data_bind][textual.dom.DOMNode.data_bind] on a widget.
 This method accepts reactives (as class attributes) in positional arguments or keyword arguments.

src/textual/dom.py

@@ -8,7 +8,6 @@
 
 import re
 import threading
-from copy import copy
 from functools import lru_cache, partial
 from inspect import getfile
 from typing import (
@@ -280,6 +279,7 @@ def compose(self) -> ComposeResult:
                 yield WorldClock("Asia/Tokyo").data_bind(WorldClockApp.time)
             ```
 
+
         Raises:
             ReactiveError: If the data wasn't bound.
 
@@ -335,10 +335,8 @@ def setter(value: object) -> None:
                     """Set bound data."""
                     _rich_traceback_omit = True
                     Reactive._initialize_object(self)
-                    # Copy the bound value
-                    # Sharing the same instance with mutable objects can lead to confusing behavior
-                    # Wrap the value in `_Mutated` so the setter knows to invoke watchers etc
-                    setattr(self, variable_name, _Mutated(copy(value)))
+                    # Wrap the value in `_Mutated` so the setter knows to invoke watchers etc.
+                    setattr(self, variable_name, _Mutated(value))
 
                 return setter