docs and expanded keys

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - Moved Ctrl+C, tab, and shift+tab to App BINDINGS
+- Deprecated `PRIORITY_BINDINGS` class variable.
 
 ## [0.7.0] - 2022-12-17
 

docs/guide/actions.md

@@ -90,6 +90,8 @@ Textual will run actions bound to keys. The following example adds key [bindings
 
 If you run this example, you can change the background by pressing keys in addition to clicking links.
 
+See the previous section on [input](./input.md#bindings) for more information on bindings.
+
 ## Namespaces
 
 Textual will look for action methods in the class where they are defined (App, Screen, or Widget). If we were to create a [custom widget](./widgets.md#custom-widgets) it can have its own set of actions.

docs/guide/input.md

@@ -10,7 +10,7 @@ This chapter will discuss how to make your app respond to input in the form of k
 
 ## Keyboard input
 
-The most fundamental way to receive input is via [Key][textual.events.Key] events. Let's write an app to show key events as you type.
+The most fundamental way to receive input is via [Key][textual.events.Key] events which are sent to your app when the user presses a key. Let's write an app to show key events as you type.
 
 === "key01.py"
 
@@ -23,7 +23,7 @@ The most fundamental way to receive input is via [Key][textual.events.Key] event
     ```{.textual path="docs/examples/guide/input/key01.py", press="T,e,x,t,u,a,l,!,_"}
     ```
 
-When you press a key, the app will receive the associated event and write it to a [TextLog](../widgets/text_log.md) widget. Try pressing a few keys to see what happens.
+When you press a key, the app will receive the event and write it to a [TextLog](../widgets/text_log.md) widget. Try pressing a few keys to see what happens.
 
 !!! tip
 
@@ -31,8 +31,7 @@ When you press a key, the app will receive the associated event and write it to
 
 ### Key Event
 
-The key event contains a number of attributes which tell you what key (or keys) have been pressed.
+The key event contains following attributes which your app can use to know how to respond.
-
 
 #### key
 
@@ -48,13 +47,13 @@ Many keys can also be combined with ++ctrl++ which will prefix the key with `ctr
 
 #### character
 
-If the key has an associated printable character then the `character` will contain a string containing a single unicode character. If there is no printable character for the key (such as for function keys) then `character` will be `None`.
+If the key has an associated printable character then `character` will contain a string with a single unicode character. If there is no printable character for the key (such as for function keys) then `character` will be `None`.
 
 For example the ++p++ key will produce `character="p"` but ++f2++ will produce `character=None`.
 
 #### name
 
-The `name` attribute is similar to `key` but unlike `key` is guaranteed to be valid within a Python function name. Textual derives `name` from the `key` key attribute by lower casing it and replacing `+` with `_`. Upper case letters are prefixed with `upper_` to distinguish them from lower case names.
+The `name` attribute is similar to `key` but, unlike `key`, is guaranteed to be valid within a Python function name. Textual derives `name` from the `key`  attribute by lower casing it and replacing `+` with `_`. Upper case letters are prefixed with `upper_` to distinguish them from lower case names.
 
 For example, ++ctrl+q++ produces `name="ctrl_p"` and ++shift+p++ produces `name="upper_p"`.
 
@@ -64,7 +63,7 @@ The `is_printable` attribute is a boolean which indicates if the key would typic
 
 #### aliases
 
-Some keys or combinations of keys can produce the same key. For instance, the ++tab++ key is indistinguishable from ++ctrl+i++ in the terminal. For such keys, Textual events will contain a list of the possible keys that may have produced this event. In the case of ++tab++, the `aliases` attribute will contain `["tab", "ctrl+i"]`
+Some keys or combinations of keys can produce the same event. For instance, the ++tab++ key is indistinguishable from ++ctrl+i++ in the terminal. For such keys, Textual events will contain a list of the possible keys that may have produced this event. In the case of ++tab++, the `aliases` attribute will contain `["tab", "ctrl+i"]`
 
 
 ### Key methods
@@ -155,24 +154,28 @@ Note how the footer displays bindings and makes them clickable.
     Multiple keys can be bound to a single action by comma-separating them.
     For example, `("r,t", "add_bar('red')", "Add Red")` means both ++r++ and ++t++ are bound to `add_bar('red')`.
 
-
-!!! note
-
-    Ordinarily a binding on a focused widget has precedence over the same key binding at a higher level. However, bindings at the `App` or `Screen` level always have priority.
-
-    The priority of a single binding can be controlled with the `priority` parameter of a `Binding` instance. Set it to `True` to give it priority, or `False` to not.
-
-    The default priority of all bindings on a class can be controlled with the `PRIORITY_BINDINGS` class variable. Set it to `True` or `False` to set the default priority for all `BINDINGS`.
-
 ### Binding class
 
 The tuple of three strings may be enough for simple bindings, but you can also replace the tuple with a [Binding][textual.binding.Binding] instance which exposes a few more options.
 
-### Why use bindings?
+### Priority bindings
 
-Bindings are particularly useful for configurable hot-keys. Bindings can also be inspected in widgets such as [Footer](../widgets/footer.md).
+Textual checks bindings for the focused widget first. If there is no matching binding, then the parent widget(s) will be checked. Occasionally, you may want bindings to be checked *before* the focused widget. Typically to create hot-keys.
+
+You can create priority key bindings by setting `priority=True` on the Binding object. Textual uses this feature to add a default binding for ++ctrl+c++ so there is always a way to exit the app. Here's the bindings from the App base class. Note the first binding is set as a priority:
+
+```python
+    BINDINGS = [
+        Binding("ctrl+c", "quit", "Quit", show=False, priority=True),
+        Binding("tab", "focus_next", "Focus Next", show=False),
+        Binding("shift+tab", "focus_previous", "Focus Previous", show=False),
+    ]
+```
+
+### Show bindings
+
+The [footer](../widgets/footer.md) widget can inspect bindings to display available keys. If you don't want a binding to display in the footer you can set `show=False`. The default bindings on App do this so that the standard ++ctrl+c++, ++tab++ and ++shift+tab++ bindings don't typically appear in the footer.
 
-In a future version of Textual it will also be possible to specify bindings in a configuration file, which will allow users to override app bindings.
 
 ## Mouse Input
 

src/textual/app.py

@@ -232,8 +232,6 @@ class App(Generic[ReturnType], DOMNode):
     }
     """
 
-    PRIORITY_BINDINGS = True
-
     SCREENS: dict[str, Screen | Callable[[], Screen]] = {}
     _BASE_PATH: str | None = None
     CSS_PATH: CSSPathType = None
@@ -242,10 +240,8 @@ class App(Generic[ReturnType], DOMNode):
 
     BINDINGS = [
         Binding("ctrl+c", "quit", "Quit", show=False, priority=True),
-        Binding("tab", "focus_next", "Focus Next", show=False, priority=False),
+        Binding("tab", "focus_next", "Focus Next", show=False),
-        Binding(
+        Binding("shift+tab", "focus_previous", "Focus Previous", show=False),
-            "shift+tab", "focus_previous", "Focus Previous", show=False, priority=False
-        ),
     ]
 
     title: Reactive[str] = Reactive("")

src/textual/binding.py

@@ -5,6 +5,7 @@ from typing import Iterable, MutableMapping
 
 import rich.repr
 
+from textual.keys import _character_to_key
 from textual._typing import TypeAlias
 
 BindingType: TypeAlias = "Binding | tuple[str, str, str]"
@@ -32,7 +33,7 @@ class Binding:
     """bool: Show the action in Footer, or False to hide."""
     key_display: str | None = None
     """str | None: How the key should be shown in footer."""
-    priority: bool | None = None
+    priority: bool = False
     """bool | None: Is this a priority binding, checked form app down to focused widget?"""
 
 
@@ -43,13 +44,11 @@ class Bindings:
     def __init__(
         self,
         bindings: Iterable[BindingType] | None = None,
-        default_priority: bool | None = None,
     ) -> None:
         """Initialise a collection of bindings.
 
         Args:
             bindings (Iterable[BindingType] | None, optional): An optional set of initial bindings.
-            default_priority (bool | None, optional): The default priority of the bindings.
 
         Note:
             The iterable of bindings can contain either a `Binding`
@@ -71,17 +70,16 @@ class Bindings:
                 # be a list of keys, so now we unroll that single Binding
                 # into a (potential) collection of Binding instances.
                 for key in binding.key.split(","):
+                    key = key.strip()
+                    if len(key) == 1:
+                        key = _character_to_key(key)
                     yield Binding(
                         key=key.strip(),
                         action=binding.action,
                         description=binding.description,
                         show=binding.show,
                         key_display=binding.key_display,
-                        priority=(
+                        priority=binding.priority,
-                            default_priority
-                            if binding.priority is None
-                            else binding.priority
-                        ),
                     )
 
         self.keys: MutableMapping[str, Binding] = (

src/textual/dom.py

@@ -92,9 +92,6 @@ class DOMNode(MessagePump):
     # Virtual DOM nodes
     COMPONENT_CLASSES: ClassVar[set[str]] = set()
 
-    # Should the content of BINDINGS be treated as priority bindings?
-    PRIORITY_BINDINGS: ClassVar[bool] = False
-
     # Mapping of key bindings
     BINDINGS: ClassVar[list[BindingType]] = []
 
@@ -233,13 +230,13 @@ class DOMNode(MessagePump):
 
         for base in reversed(cls.__mro__):
             if issubclass(base, DOMNode):
-                # See if the current class wants to set the bindings as
-                # priority bindings. If it doesn't have that property on the
-                # class, go with what we saw last.
-                priority = base.__dict__.get("PRIORITY_BINDINGS", priority)
                 if not base._inherit_bindings:
                     bindings.clear()
-                bindings.append(Bindings(base.__dict__.get("BINDINGS", []), priority))
+                bindings.append(
+                    Bindings(
+                        base.__dict__.get("BINDINGS", []),
+                    )
+                )
         keys = {}
         for bindings_ in bindings:
             keys.update(bindings_.keys)

src/textual/keys.py

@@ -256,3 +256,14 @@ def _get_key_display(key: str) -> str:
     if unicode_character.isprintable():
         return unicode_character
     return upper_original
+
+
+def _character_to_key(character: str) -> str:
+    """Convert a single character to a key value."""
+    assert len(character) == 1
+    if not character.isalnum():
+        key = unicodedata.name(character).lower().replace("-", "_").replace(" ", "_")
+    else:
+        key = character
+    key = KEY_NAME_REPLACEMENTS.get(key, key)
+    return key

src/textual/screen.py

@@ -29,7 +29,6 @@ class Screen(Widget):
     # The screen is a special case and unless a class that inherits from us
     # says otherwise, all screen-level bindings should be treated as having
     # priority.
-    PRIORITY_BINDINGS = True
 
     DEFAULT_CSS = """
     Screen {

tests/test_binding_inheritance.py

@@ -57,7 +57,7 @@ async def test_just_app_no_bindings() -> None:
 class AlphaBinding(App[None]):
     """An app with a simple alpha key binding."""
 
-    BINDINGS = [Binding("a", "a", "a")]
+    BINDINGS = [Binding("a", "a", "a", priority=True)]
 
 
 async def test_just_app_alpha_binding() -> None:
@@ -81,8 +81,7 @@ async def test_just_app_alpha_binding() -> None:
 class LowAlphaBinding(App[None]):
     """An app with a simple low-priority alpha key binding."""
 
-    PRIORITY_BINDINGS = False
+    BINDINGS = [Binding("a", "a", "a", priority=False)]
-    BINDINGS = [Binding("a", "a", "a")]
 
 
 async def test_just_app_low_priority_alpha_binding() -> None:
@@ -106,7 +105,7 @@ async def test_just_app_low_priority_alpha_binding() -> None:
 class ScreenWithBindings(Screen):
     """A screen with a simple alpha key binding."""
 
-    BINDINGS = [Binding("a", "a", "a")]
+    BINDINGS = [Binding("a", "a", "a", priority=True)]
 
 
 class AppWithScreenThatHasABinding(App[None]):
@@ -144,8 +143,7 @@ async def test_app_screen_with_bindings() -> None:
 class ScreenWithLowBindings(Screen):
     """A screen with a simple low-priority alpha key binding."""
 
-    PRIORITY_BINDINGS = False
+    BINDINGS = [Binding("a", "a", "a", priority=False)]
-    BINDINGS = [Binding("a", "a", "a")]
 
 
 class AppWithScreenThatHasALowBinding(App[None]):

tests/test_xterm_parser.py

@@ -106,7 +106,7 @@ def test_cant_match_escape_sequence_too_long(parser):
     # The rest of the characters correspond to the expected key presses
     events = events[1:]
     for index, character in enumerate(sequence[1:]):
-        assert events[index].char == character
+        assert events[index].character == character
 
 
 @pytest.mark.parametrize(