copy bindings (#2176)

* copy bindings

* changelog

* simplify

Author: willmcgugan

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+
+### Fixed
+
+- Fixed bindings persistance https://github.com/Textualize/textual/issues/1613
+
 ## [0.17.1] - 2023-03-30
 
 ### Fixed

src/textual/binding.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Iterable, MutableMapping
+from typing import TYPE_CHECKING, Iterable
 
 import rich.repr
 
@@ -92,12 +92,22 @@ def make_bindings(bindings: Iterable[BindingType]) -> Iterable[Binding]:
                         priority=binding.priority,
                     )
 
-        self.keys: MutableMapping[str, Binding] = (
+        self.keys: dict[str, Binding] = (
             {binding.key: binding for binding in make_bindings(bindings)}
             if bindings
             else {}
         )
 
+    def copy(self) -> Bindings:
+        """Return a copy of this instance.
+
+        Return:
+            New bindings object.
+        """
+        copy = Bindings()
+        copy.keys = self.keys.copy()
+        return copy
+
     def __rich_repr__(self) -> rich.repr.Result:
         yield self.keys
 

src/textual/dom.py

@@ -165,7 +165,11 @@ def __init__(
         self._auto_refresh: float | None = None
         self._auto_refresh_timer: Timer | None = None
         self._css_types = {cls.__name__ for cls in self._css_bases(self.__class__)}
-        self._bindings = self._merged_bindings or Bindings()
+        self._bindings = (
+            Bindings()
+            if self._merged_bindings is None
+            else self._merged_bindings.copy()
+        )
         self._has_hover_style: bool = False
         self._has_focus_within: bool = False